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2	<html>
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6	<title>NCURSES Programming HOWTO</title>
7	<meta name="GENERATOR" content=
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10	<body class="ARTICLE" bgcolor="#FFFFFF" text="#000000" link=
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12	<div class="ARTICLE">
13	<div class="TITLEPAGE">
14	<h1 class="TITLE"><a name="AEN2" id="AEN2">NCURSES Programming
15	HOWTO</a></h1>
16	<h3 class="AUTHOR"><a name="AEN4" id="AEN4">Pradeep Padala</a></h3>
17	<div class="AFFILIATION">
18	<div class="ADDRESS">
19	<p class="ADDRESS"><code class="EMAIL"><<a href=
20	"mailto:ppadala@gmail.com">ppadala@gmail.com</a>></code></p>
21	</div>
22	</div>
23	<p class="PUBDATE">v1.9, 2005-06-20<br></p>
24	<div class="REVHISTORY">
25	<table width="100%" border="0">
26	<tr>
27	<th align="left" valign="top" colspan="3"><b>Revision
28	History</b></th>
29	</tr>
30	<tr>
31	<td align="left">Revision 1.9</td>
32	<td align="left">2005-06-20</td>
33	<td align="left">Revised by: ppadala</td>
34	</tr>
35	<tr>
36	<td align="left" colspan="3">The license has been changed to the
37	MIT-style license used by NCURSES. Note that the programs are also
38	re-licensed under this.</td>
39	</tr>
40	<tr>
41	<td align="left">Revision 1.8</td>
42	<td align="left">2005-06-17</td>
43	<td align="left">Revised by: ppadala</td>
44	</tr>
45	<tr>
46	<td align="left" colspan="3">Lots of updates. Added references and
47	perl examples. Changes to examples. Many grammatical and stylistic
48	changes to the content. Changes to NCURSES history.</td>
49	</tr>
50	<tr>
51	<td align="left">Revision 1.7.1</td>
52	<td align="left">2002-06-25</td>
53	<td align="left">Revised by: ppadala</td>
54	</tr>
55	<tr>
56	<td align="left" colspan="3">Added a README file for building and
57	instructions for building from source.</td>
58	</tr>
59	<tr>
60	<td align="left">Revision 1.7</td>
61	<td align="left">2002-06-25</td>
62	<td align="left">Revised by: ppadala</td>
63	</tr>
64	<tr>
65	<td align="left" colspan="3">Added "Other formats" section and made
66	a lot of fancy changes to the programs. Inlining of programs is
67	gone.</td>
68	</tr>
69	<tr>
70	<td align="left">Revision 1.6.1</td>
71	<td align="left">2002-02-24</td>
72	<td align="left">Revised by: ppadala</td>
73	</tr>
74	<tr>
75	<td align="left" colspan="3">Removed the old Changelog section,
76	cleaned the makefiles</td>
77	</tr>
78	<tr>
79	<td align="left">Revision 1.6</td>
80	<td align="left">2002-02-16</td>
81	<td align="left">Revised by: ppadala</td>
82	</tr>
83	<tr>
84	<td align="left" colspan="3">Corrected a lot of spelling mistakes,
85	added ACS variables section</td>
86	</tr>
87	<tr>
88	<td align="left">Revision 1.5</td>
89	<td align="left">2002-01-05</td>
90	<td align="left">Revised by: ppadala</td>
91	</tr>
92	<tr>
93	<td align="left" colspan="3">Changed structure to present proper
94	TOC</td>
95	</tr>
96	<tr>
97	<td align="left">Revision 1.3.1</td>
98	<td align="left">2001-07-26</td>
99	<td align="left">Revised by: ppadala</td>
100	</tr>
101	<tr>
102	<td align="left" colspan="3">Corrected maintainers paragraph,
103	Corrected stable release number</td>
104	</tr>
105	<tr>
106	<td align="left">Revision 1.3</td>
107	<td align="left">2001-07-24</td>
108	<td align="left">Revised by: ppadala</td>
109	</tr>
110	<tr>
111	<td align="left" colspan="3">Added copyright notices to main
112	document (LDP license) and programs (GPL), Corrected
113	printw_example.</td>
114	</tr>
115	<tr>
116	<td align="left">Revision 1.2</td>
117	<td align="left">2001-06-05</td>
118	<td align="left">Revised by: ppadala</td>
119	</tr>
120	<tr>
121	<td align="left" colspan="3">Incorporated ravi's changes. Mainly to
122	introduction, menu, form, justforfun sections</td>
123	</tr>
124	<tr>
125	<td align="left">Revision 1.1</td>
126	<td align="left">2001-05-22</td>
127	<td align="left">Revised by: ppadala</td>
128	</tr>
129	<tr>
130	<td align="left" colspan="3">Added "a word about window" section,
131	Added scanw_example.</td>
132	</tr>
133	</table>
134	</div>
135	<div>
136	<div class="ABSTRACT"><a name="AEN67" id="AEN67"></a>
137	<p><em>This document is intended to be an "All in One" guide for
138	programming with ncurses and its sister libraries. We graduate from
139	a simple "Hello World" program to more complex form manipulation.
140	No prior experience in ncurses is assumed. Send comments to
141	<a href="mailto:ppadala@gmail.com" target="_top">this
142	address</a></em></p>
143	</div>
144	</div>
145	<hr></div>
146	<div class="TOC">
147	<dl>
148	<dt><b>Table of Contents</b></dt>
149	<dt>1. <a href="#INTRO">Introduction</a></dt>
150	<dd>
151	<dl>
152	<dt>1.1. <a href="#WHATIS">What is NCURSES?</a></dt>
153	<dt>1.2. <a href="#WHATCANWEDO">What we can do with
154	NCURSES</a></dt>
155	<dt>1.3. <a href="#WHERETOGETIT">Where to get it</a></dt>
156	<dt>1.4. <a href="#PURPOSE">Purpose/Scope of the document</a></dt>
157	<dt>1.5. <a href="#ABOUTPROGRAMS">About the Programs</a></dt>
158	<dt>1.6. <a href="#OTHERFORMATS">Other Formats of the
159	document</a></dt>
160	<dt>1.7. <a href="#CREDITS">Credits</a></dt>
161	<dt>1.8. <a href="#WISHLIST">Wish List</a></dt>
162	<dt>1.9. <a href="#COPYRIGHT">Copyright</a></dt>
163	</dl>
164	</dd>
165	<dt>2. <a href="#HELLOWORLD">Hello World !!!</a></dt>
166	<dd>
167	<dl>
168	<dt>2.1. <a href="#COMPILECURSES">Compiling With the NCURSES
169	Library</a></dt>
170	<dt>2.2. <a href="#DISSECTION">Dissection</a></dt>
171	</dl>
172	</dd>
173	<dt>3. <a href="#GORY">The Gory Details</a></dt>
174	<dt>4. <a href="#INIT">Initialization</a></dt>
175	<dd>
176	<dl>
177	<dt>4.1. <a href="#ABOUTINIT">Initialization functions</a></dt>
178	<dt>4.2. <a href="#RAWCBREAK">raw() and cbreak()</a></dt>
179	<dt>4.3. <a href="#ECHONOECHO">echo() and noecho()</a></dt>
180	<dt>4.4. <a href="#KEYPAD">keypad()</a></dt>
181	<dt>4.5. <a href="#HALFDELAY">halfdelay()</a></dt>
182	<dt>4.6. <a href="#MISCINIT">Miscellaneous Initialization
183	functions</a></dt>
184	<dt>4.7. <a href="#INITEX">An Example</a></dt>
185	</dl>
186	</dd>
187	<dt>5. <a href="#AWORDWINDOWS">A Word about Windows</a></dt>
188	<dt>6. <a href="#PRINTW">Output functions</a></dt>
189	<dd>
190	<dl>
191	<dt>6.1. <a href="#ADDCHCLASS">addch() class of functions</a></dt>
192	<dt>6.2. <a href="#AEN298">mvaddch(), waddch() and
193	mvwaddch()</a></dt>
194	<dt>6.3. <a href="#PRINTWCLASS">printw() class of
195	functions</a></dt>
196	<dt>6.4. <a href="#ADDSTRCLASS">addstr() class of
197	functions</a></dt>
198	<dt>6.5. <a href="#ACAUTION">A word of caution</a></dt>
199	</dl>
200	</dd>
201	<dt>7. <a href="#SCANW">Input functions</a></dt>
202	<dd>
203	<dl>
204	<dt>7.1. <a href="#GETCHCLASS">getch() class of functions</a></dt>
205	<dt>7.2. <a href="#SCANWCLASS">scanw() class of functions</a></dt>
206	<dt>7.3. <a href="#GETSTRCLASS">getstr() class of
207	functions</a></dt>
208	<dt>7.4. <a href="#GETSTREX">Some examples</a></dt>
209	</dl>
210	</dd>
211	<dt>8. <a href="#ATTRIB">Attributes</a></dt>
212	<dd>
213	<dl>
214	<dt>8.1. <a href="#ATTRIBDETAILS">The details</a></dt>
215	<dt>8.2. <a href="#ATTRONVSATTRSET">attron() vs attrset()</a></dt>
216	<dt>8.3. <a href="#ATTR_GET">attr_get()</a></dt>
217	<dt>8.4. <a href="#ATTR_FUNCS">attr_ functions</a></dt>
218	<dt>8.5. <a href="#WATTRFUNCS">wattr functions</a></dt>
219	<dt>8.6. <a href="#CHGAT">chgat() functions</a></dt>
220	</dl>
221	</dd>
222	<dt>9. <a href="#WINDOWS">Windows</a></dt>
223	<dd>
224	<dl>
225	<dt>9.1. <a href="#WINDOWBASICS">The basics</a></dt>
226	<dt>9.2. <a href="#LETBEWINDOW">Let there be a Window !!!</a></dt>
227	<dt>9.3. <a href="#BORDEREXEXPL">Explanation</a></dt>
228	<dt>9.4. <a href="#OTHERSTUFF">The other stuff in the
229	example</a></dt>
230	<dt>9.5. <a href="#OTHERBORDERFUNCS">Other Border
231	functions</a></dt>
232	</dl>
233	</dd>
234	<dt>10. <a href="#COLOR">Colors</a></dt>
235	<dd>
236	<dl>
237	<dt>10.1. <a href="#COLORBASICS">The basics</a></dt>
238	<dt>10.2. <a href="#CHANGECOLORDEFS">Changing Color
239	Definitions</a></dt>
240	<dt>10.3. <a href="#COLORCONTENT">Color Content</a></dt>
241	</dl>
242	</dd>
243	<dt>11. <a href="#KEYS">Interfacing with the key board</a></dt>
244	<dd>
245	<dl>
246	<dt>11.1. <a href="#KEYSBASICS">The Basics</a></dt>
247	<dt>11.2. <a href="#SIMPLEKEYEX">A Simple Key Usage
248	example</a></dt>
249	</dl>
250	</dd>
251	<dt>12. <a href="#MOUSE">Interfacing with the mouse</a></dt>
252	<dd>
253	<dl>
254	<dt>12.1. <a href="#MOUSEBASICS">The Basics</a></dt>
255	<dt>12.2. <a href="#GETTINGEVENTS">Getting the events</a></dt>
256	<dt>12.3. <a href="#MOUSETOGETHER">Putting it all Together</a></dt>
257	<dt>12.4. <a href="#MISCMOUSEFUNCS">Miscellaneous
258	Functions</a></dt>
259	</dl>
260	</dd>
261	<dt>13. <a href="#SCREEN">Screen Manipulation</a></dt>
262	<dd>
263	<dl>
264	<dt>13.1. <a href="#GETYX">getyx() functions</a></dt>
265	<dt>13.2. <a href="#SCREENDUMP">Screen Dumping</a></dt>
266	<dt>13.3. <a href="#WINDOWDUMP">Window Dumping</a></dt>
267	</dl>
268	</dd>
269	<dt>14. <a href="#MISC">Miscellaneous features</a></dt>
270	<dd>
271	<dl>
272	<dt>14.1. <a href="#CURSSET">curs_set()</a></dt>
273	<dt>14.2. <a href="#TEMPLEAVE">Temporarily Leaving Curses
274	mode</a></dt>
275	<dt>14.3. <a href="#ACSVARS">ACS_ variables</a></dt>
276	</dl>
277	</dd>
278	<dt>15. <a href="#OTHERLIB">Other libraries</a></dt>
279	<dt>16. <a href="#PANELS">Panel Library</a></dt>
280	<dd>
281	<dl>
282	<dt>16.1. <a href="#PANELBASICS">The Basics</a></dt>
283	<dt>16.2. <a href="#COMPILEPANELS">Compiling With the Panels
284	Library</a></dt>
285	<dt>16.3. <a href="#PANELBROWSING">Panel Window Browsing</a></dt>
286	<dt>16.4. <a href="#USERPTRUSING">Using User Pointers</a></dt>
287	<dt>16.5. <a href="#PANELMOVERESIZE">Moving and Resizing
288	Panels</a></dt>
289	<dt>16.6. <a href="#PANELSHOWHIDE">Hiding and Showing
290	Panels</a></dt>
291	<dt>16.7. <a href="#PANELABOVE">panel_above() and panel_below()
292	Functions</a></dt>
293	</dl>
294	</dd>
295	<dt>17. <a href="#MENUS">Menus Library</a></dt>
296	<dd>
297	<dl>
298	<dt>17.1. <a href="#MENUBASICS">The Basics</a></dt>
299	<dt>17.2. <a href="#COMPILEMENUS">Compiling With the Menu
300	Library</a></dt>
301	<dt>17.3. <a href="#MENUDRIVER">Menu Driver: The work horse of the
302	menu system</a></dt>
303	<dt>17.4. <a href="#MENUWINDOWS">Menu Windows</a></dt>
304	<dt>17.5. <a href="#SCROLLMENUS">Scrolling Menus</a></dt>
305	<dt>17.6. <a href="#MULTICOLUMN">Multi Columnar Menus</a></dt>
306	<dt>17.7. <a href="#MULTIVALUEMENUS">Multi Valued Menus</a></dt>
307	<dt>17.8. <a href="#MENUOPT">Menu Options</a></dt>
308	<dt>17.9. <a href="#MENUUSERPTR">The useful User Pointer</a></dt>
309	</dl>
310	</dd>
311	<dt>18. <a href="#FORMS">Forms Library</a></dt>
312	<dd>
313	<dl>
314	<dt>18.1. <a href="#FORMBASICS">The Basics</a></dt>
315	<dt>18.2. <a href="#COMPILEFORMS">Compiling With the Forms
316	Library</a></dt>
317	<dt>18.3. <a href="#PLAYFIELDS">Playing with Fields</a></dt>
318	<dt>18.4. <a href="#FORMWINDOWS">Form Windows</a></dt>
319	<dt>18.5. <a href="#FILEDVALIDATE">Field Validation</a></dt>
320	<dt>18.6. <a href="#FORMDRIVER">Form Driver: The work horse of the
321	forms system</a></dt>
322	</dl>
323	</dd>
324	<dt>19. <a href="#TOOLS">Tools and Widget Libraries</a></dt>
325	<dd>
326	<dl>
327	<dt>19.1. <a href="#CDK">CDK (Curses Development Kit)</a></dt>
328	<dt>19.2. <a href="#DIALOG">The dialog</a></dt>
329	<dt>19.3. <a href="#PERLCURSES">Perl Curses Modules CURSES::FORM
330	and CURSES::WIDGETS</a></dt>
331	</dl>
332	</dd>
333	<dt>20. <a href="#JUSTFORFUN">Just For Fun !!!</a></dt>
334	<dd>
335	<dl>
336	<dt>20.1. <a href="#GAMEOFLIFE">The Game of Life</a></dt>
337	<dt>20.2. <a href="#MAGIC">Magic Square</a></dt>
338	<dt>20.3. <a href="#HANOI">Towers of Hanoi</a></dt>
339	<dt>20.4. <a href="#QUEENS">Queens Puzzle</a></dt>
340	<dt>20.5. <a href="#SHUFFLE">Shuffle</a></dt>
341	<dt>20.6. <a href="#TT">Typing Tutor</a></dt>
342	</dl>
343	</dd>
344	<dt>21. <a href="#REF">References</a></dt>
345	</dl>
346	</div>
347	<div class="SECT1">
348	<h2 class="SECT1"><a name="INTRO" id="INTRO">1.
349	Introduction</a></h2>
350	<p>In the olden days of teletype terminals, terminals were away
351	from computers and were connected to them through serial cables.
352	The terminals could be configured by sending a series of bytes. All
353	the capabilities (such as moving the cursor to a new location,
354	erasing part of the screen, scrolling the screen, changing modes
355	etc.) of terminals could be accessed through these series of bytes.
356	These control seeuqnces are usually called escape sequences,
357	because they start with an escape(0x1B) character. Even today, with
358	proper emulation, we can send escape sequences to the emulator and
359	achieve the same effect on a terminal window.</p>
360	<p>Suppose you wanted to print a line in color. Try typing this on
361	your console.</p>
362	<table border="0" bgcolor="#E0E0E0" width="100%">
363	<tr>
364	<td>
365	<pre class="PROGRAMLISTING">
366	<font color="#000000">echo "^[[0;31;40mIn Color"</font>
367	</pre></td>
368	</tr>
369	</table>
370	<p>The first character is an escape character, which looks like two
371	characters ^ and [. To be able to print it, you have to press
372	CTRL+V and then the ESC key. All the others are normal printable
373	characters. You should be able to see the string "In Color" in red.
374	It stays that way and to revert back to the original mode type
375	this.</p>
376	<table border="0" bgcolor="#E0E0E0" width="100%">
377	<tr>
378	<td>
379	<pre class="PROGRAMLISTING">
380	<font color="#000000">echo "^[[0;37;40m"</font>
381	</pre></td>
382	</tr>
383	</table>
384	<p>Now, what do these magic characters mean? Difficult to
385	comprehend? They might even be different for different terminals.
386	So the designers of UNIX invented a mechanism named <var class=
387	"LITERAL">termcap</var>. It is a file that lists all the
388	capabilities of a particular terminal, along with the escape
389	sequences needed to achieve a particular effect. In the later
390	years, this was replaced by <var class="LITERAL">terminfo</var>.
391	Without delving too much into details, this mechanism allows
392	application programs to query the terminfo database and obtain the
393	control characters to be sent to a terminal or terminal
394	emulator.</p>
395	<div class="SECT2">
396	<hr>
397	<h3 class="SECT2"><a name="WHATIS" id="WHATIS">1.1. What is
398	NCURSES?</a></h3>
399	<p>You might be wondering, what the import of all this technical
400	gibberish is. In the above scenario, every application program is
401	supposed to query the terminfo and perform the necessary stuff
402	(sending control characters etc.). It soon became difficult to
403	manage this complexity and this gave birth to 'CURSES'. Curses is a
404	pun on the name "cursor optimization". The Curses library forms a
405	wrapper over working with raw terminal codes, and provides highly
406	flexible and efficient API (Application Programming Interface). It
407	provides functions to move the cursor, create windows, produce
408	colors, play with mouse etc. The application programs need not
409	worry about the underlying terminal capabilities.</p>
410	<p>So what is NCURSES? NCURSES is a clone of the original System V
411	Release 4.0 (SVr4) curses. It is a freely distributable library,
412	fully compatible with older version of curses. In short, it is a
413	library of functions that manages an application's display on
414	character-cell terminals. In the remainder of the document, the
415	terms curses and ncurses are used interchangeably.</p>
416	<p>A detailed history of NCURSES can be found in the NEWS file from
417	the source distribution. The current package is maintained by
418	<a href="mailto:dickey@his.com" target="_top">Thomas Dickey</a>.
419	You can contact the maintainers at <a href=
420	"mailto:bug-ncurses@gnu.org" target=
421	"_top">bug-ncurses@gnu.org</a>.</p>
422	</div>
423	<div class="SECT2">
424	<hr>
425	<h3 class="SECT2"><a name="WHATCANWEDO" id="WHATCANWEDO">1.2. What
426	we can do with NCURSES</a></h3>
427	<p>NCURSES not only creates a wrapper over terminal capabilities,
428	but also gives a robust framework to create nice looking UI (User
429	Interface)s in text mode. It provides functions to create windows
430	etc. Its sister libraries panel, menu and form provide an extension
431	to the basic curses library. These libraries usually come along
432	with curses. One can create applications that contain multiple
433	windows, menus, panels and forms. Windows can be managed
434	independently, can provide 'scrollability' and even can be
435	hidden.</p>
436	<p>Menus provide the user with an easy command selection option.
437	Forms allow the creation of easy-to-use data entry and display
438	windows. Panels extend the capabilities of ncurses to deal with
439	overlapping and stacked windows.</p>
440	<p>These are just some of the basic things we can do with ncurses.
441	As we move along, We will see all the capabilities of these
442	libraries.</p>
443	</div>
444	<div class="SECT2">
445	<hr>
446	<h3 class="SECT2"><a name="WHERETOGETIT" id="WHERETOGETIT">1.3.
447	Where to get it</a></h3>
448	<p>All right, now that you know what you can do with ncurses, you
449	must be rearing to get started. NCURSES is usually shipped with
450	your installation. In case you don't have the library or want to
451	compile it on your own, read on.</p>
452	<p><em>Compiling the package</em></p>
453	<p>NCURSES can be obtained from <a href=
454	"ftp://ftp.gnu.org/pub/gnu/ncurses/ncurses.tar.gz" target=
455	"_top">ftp://ftp.gnu.org/pub/gnu/ncurses/ncurses.tar.gz</a> or any
456	of the ftp sites mentioned in <a href=
457	"http://www.gnu.org/order/ftp.html" target=
458	"_top">http://www.gnu.org/order/ftp.html</a>.</p>
459	<p>Read the README and INSTALL files for details on to how to
460	install it. It usually involves the following operations.</p>
461	<table border="0" bgcolor="#E0E0E0" width="100%">
462	<tr>
463	<td>
464	<pre class="PROGRAMLISTING">
465	<font color=
466	"#000000"> tar zxvf ncurses<version>.tar.gz # unzip and untar the archive
467	cd ncurses<version> # cd to the directory
468	./configure # configure the build according to your
469	# environment
470	make # make it
471	su root # become root
472	make install # install it</font>
473	</pre></td>
474	</tr>
475	</table>
476	<p><em>Using the RPM</em></p>
477	<p>NCURSES RPM can be found and downloaded from <a href=
478	"http://rpmfind.net" target="_top">http://rpmfind.net</a> . The RPM
479	can be installed with the following command after becoming
480	root.</p>
481	<table border="0" bgcolor="#E0E0E0" width="100%">
482	<tr>
483	<td>
484	<pre class="PROGRAMLISTING">
485	<font color="#000000"> rpm -i <downloaded rpm></font>
486	</pre></td>
487	</tr>
488	</table>
489	</div>
490	<div class="SECT2">
491	<hr>
492	<h3 class="SECT2"><a name="PURPOSE" id="PURPOSE">1.4. Purpose/Scope
493	of the document</a></h3>
494	<p>This document is intended to be a "All in One" guide for
495	programming with ncurses and its sister libraries. We graduate from
496	a simple "Hello World" program to more complex form manipulation.
497	No prior experience in ncurses is assumed. The writing is informal,
498	but a lot of detail is provided for each of the examples.</p>
499	</div>
500	<div class="SECT2">
501	<hr>
502	<h3 class="SECT2"><a name="ABOUTPROGRAMS" id="ABOUTPROGRAMS">1.5.
503	About the Programs</a></h3>
504	<p>All the programs in the document are available in zipped form
505	<a href=
506	"http://www.tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs.tar.gz"
507	target="_top">here</a>. Unzip and untar it. The directory structure
508	looks like this.</p>
509	<table border="0" bgcolor="#E0E0E0" width="100%">
510	<tr>
511	<td>
512	<pre class="PROGRAMLISTING">
513	<font color="#000000">ncurses
514	\|
515	\|----> JustForFun -- just for fun programs
516	\|----> basics -- basic programs
517	\|----> demo -- output files go into this directory after make
518	\| \|
519	\| \|----> exe -- exe files of all example programs
520	\|----> forms -- programs related to form library
521	\|----> menus -- programs related to menus library
522	\|----> panels -- programs related to panels library
523	\|----> perl -- perl equivalents of the examples (contributed
524	\| by Anuradha Ratnaweera)
525	\|----> Makefile -- the top level Makefile
526	\|----> README -- the top level README file. contains instructions
527	\|----> COPYING -- copyright notice</font>
528	</pre></td>
529	</tr>
530	</table>
531	<p>The individual directories contain the following files.</p>
532	<table border="0" bgcolor="#E0E0E0" width="100%">
533	<tr>
534	<td>
535	<pre class="PROGRAMLISTING">
536	<font color="#000000">Description of files in each directory
537	--------------------------------------
538	JustForFun
539	\|
540	\|----> hanoi.c -- The Towers of Hanoi Solver
541	\|----> life.c -- The Game of Life demo
542	\|----> magic.c -- An Odd Order Magic Square builder
543	\|----> queens.c -- The famous N-Queens Solver
544	\|----> shuffle.c -- A fun game, if you have time to kill
545	\|----> tt.c -- A very trivial typing tutor
546
547	basics
548	\|
549	\|----> acs_vars.c -- ACS_ variables example
550	\|----> hello_world.c -- Simple "Hello World" Program
551	\|----> init_func_example.c -- Initialization functions example
552	\|----> key_code.c -- Shows the scan code of the key pressed
553	\|----> mouse_menu.c -- A menu accessible by mouse
554	\|----> other_border.c -- Shows usage of other border functions apa
555	\| -- rt from box()
556	\|----> printw_example.c -- A very simple printw() example
557	\|----> scanw_example.c -- A very simple getstr() example
558	\|----> simple_attr.c -- A program that can print a c file with
559	\| -- comments in attribute
560	\|----> simple_color.c -- A simple example demonstrating colors
561	\|----> simple_key.c -- A menu accessible with keyboard UP, DOWN
562	\| -- arrows
563	\|----> temp_leave.c -- Demonstrates temporarily leaving curses mode
564	\|----> win_border.c -- Shows Creation of windows and borders
565	\|----> with_chgat.c -- chgat() usage example
566
567	forms
568	\|
569	\|----> form_attrib.c -- Usage of field attributes
570	\|----> form_options.c -- Usage of field options
571	\|----> form_simple.c -- A simple form example
572	\|----> form_win.c -- Demo of windows associated with forms
573
574	menus
575	\|
576	\|----> menu_attrib.c -- Usage of menu attributes
577	\|----> menu_item_data.c -- Usage of item_name() etc.. functions
578	\|----> menu_multi_column.c -- Creates multi columnar menus
579	\|----> menu_scroll.c -- Demonstrates scrolling capability of menus
580	\|----> menu_simple.c -- A simple menu accessed by arrow keys
581	\|----> menu_toggle.c -- Creates multi valued menus and explains
582	\| -- REQ_TOGGLE_ITEM
583	\|----> menu_userptr.c -- Usage of user pointer
584	\|----> menu_win.c -- Demo of windows associated with menus
585
586	panels
587	\|
588	\|----> panel_browse.c -- Panel browsing through tab. Usage of user
589	\| -- pointer
590	\|----> panel_hide.c -- Hiding and Un hiding of panels
591	\|----> panel_resize.c -- Moving and resizing of panels
592	\|----> panel_simple.c -- A simple panel example
593
594	perl
595	\|----> 01-10.pl -- Perl equivalents of first ten example programs</font>
596	</pre></td>
597	</tr>
598	</table>
599	<p>There is a top level Makefile included in the main directory. It
600	builds all the files and puts the ready-to-use exes in demo/exe
601	directory. You can also do selective make by going into the
602	corresponding directory. Each directory contains a README file
603	explaining the purpose of each c file in the directory.</p>
604	<p>For every example, I have included path name for the file
605	relative to the examples directory.</p>
606	<p>If you prefer browsing individual programs, point your browser
607	to <a href=
608	"http://tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs/"
609	target=
610	"_top">http://tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs/</a></p>
611	<p>All the programs are released under the same license that is
612	used by ncurses (MIT-style). This gives you the ability to do
613	pretty much anything other than claiming them as yours. Feel free
614	to use them in your programs as appropriate.</p>
615	</div>
616	<div class="SECT2">
617	<hr>
618	<h3 class="SECT2"><a name="OTHERFORMATS" id="OTHERFORMATS">1.6.
619	Other Formats of the document</a></h3>
620	<p>This howto is also availabe in various other formats on the
621	tldp.org site. Here are the links to other formats of this
622	document.</p>
623	<div class="SECT3">
624	<hr>
625	<h4 class="SECT3"><a name="LISTFORMATS" id="LISTFORMATS">1.6.1.
626	Readily available formats from tldp.org</a></h4>
627	<ul>
628	<li>
629	<p><a href=
630	"http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/pdf/NCURSES-Programming-HOWTO.pdf"
631	target="_top">Acrobat PDF Format</a></p>
632	</li>
633	<li>
634	<p><a href=
635	"http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/ps/NCURSES-Programming-HOWTO.ps.gz"
636	target="_top">PostScript Format</a></p>
637	</li>
638	<li>
639	<p><a href=
640	"http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html/NCURSES-Programming-HOWTO-html.tar.gz"
641	target="_top">In Multiple HTML pages</a></p>
642	</li>
643	<li>
644	<p><a href=
645	"http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html_single/NCURSES-Programming-HOWTO.html"
646	target="_top">In One big HTML format</a></p>
647	</li>
648	</ul>
649	</div>
650	<div class="SECT3">
651	<hr>
652	<h4 class="SECT3"><a name="BUILDSOURCE" id="BUILDSOURCE">1.6.2.
653	Building from source</a></h4>
654	<p>If above links are broken or if you want to experiment with sgml
655	read on.</p>
656	<table border="0" bgcolor="#E0E0E0" width="100%">
657	<tr>
658	<td>
659	<pre class="PROGRAMLISTING">
660	<font color=
661	"#000000"> Get both the source and the tar,gzipped programs, available at
662	http://cvsview.tldp.org/index.cgi/LDP/howto/docbook/
663	NCURSES-HOWTO/NCURSES-Programming-HOWTO.sgml
664	http://cvsview.tldp.org/index.cgi/LDP/howto/docbook/
665	NCURSES-HOWTO/ncurses_programs.tar.gz
666
667	Unzip ncurses_programs.tar.gz with
668	tar zxvf ncurses_programs.tar.gz
669
670	Use jade to create various formats. For example if you just want to create
671	the multiple html files, you would use
672	jade -t sgml -i html -d <path to docbook html stylesheet>
673	NCURSES-Programming-HOWTO.sgml
674	to get pdf, first create a single html file of the HOWTO with
675	jade -t sgml -i html -d <path to docbook html stylesheet> -V nochunks
676	NCURSES-Programming-HOWTO.sgml > NCURSES-ONE-BIG-FILE.html
677	then use htmldoc to get pdf file with
678	htmldoc --size universal -t pdf --firstpage p1 -f <output file name.pdf>
679	NCURSES-ONE-BIG-FILE.html
680	for ps, you would use
681	htmldoc --size universal -t ps --firstpage p1 -f <output file name.ps>
682	NCURSES-ONE-BIG-FILE.html</font>
683	</pre></td>
684	</tr>
685	</table>
686	<p>See <a href="http://www.tldp.org/LDP/LDP-Author-Guide/" target=
687	"_top">LDP Author guide</a> for more details. If all else failes,
688	mail me at <a href="ppadala@gmail.com" target=
689	"_top">ppadala@gmail.com</a></p>
690	</div>
691	</div>
692	<div class="SECT2">
693	<hr>
694	<h3 class="SECT2"><a name="CREDITS" id="CREDITS">1.7.
695	Credits</a></h3>
696	<p>I thank <a href="mailto:sharath_1@usa.net" target=
697	"_top">Sharath</a> and Emre Akbas for helping me with few sections.
698	The introduction was initially written by sharath. I rewrote it
699	with few excerpts taken from his initial work. Emre helped in
700	writing printw and scanw sections.</p>
701	<p>Perl equivalents of the example programs are contributed by
702	<a href="mailto:Aratnaweera@virtusa.com" target="_top">Anuradha
703	Ratnaweera</a>.</p>
704	<p>Then comes <a href="mailto:parimi@ece.arizona.edu" target=
705	"_top">Ravi Parimi</a>, my dearest friend, who has been on this
706	project before even one line was written. He constantly bombarded
707	me with suggestions and patiently reviewed the whole text. He also
708	checked each program on Linux and Solaris.</p>
709	</div>
710	<div class="SECT2">
711	<hr>
712	<h3 class="SECT2"><a name="WISHLIST" id="WISHLIST">1.8. Wish
713	List</a></h3>
714	<p>This is the wish list, in the order of priority. If you have a
715	wish or you want to work on completing the wish, mail <a href=
716	"mailto:ppadala@gmail.com" target="_top">me</a>.</p>
717	<ul>
718	<li>
719	<p>Add examples to last parts of forms section.</p>
720	</li>
721	<li>
722	<p>Prepare a Demo showing all the programs and allow the user to
723	browse through description of each program. Let the user compile
724	and see the program in action. A dialog based interface is
725	preferred.</p>
726	</li>
727	<li>
728	<p>Add debug info. _tracef, _tracemouse stuff.</p>
729	</li>
730	<li>
731	<p>Accessing termcap, terminfo using functions provided by ncurses
732	package.</p>
733	</li>
734	<li>
735	<p>Working on two terminals simultaneously.</p>
736	</li>
737	<li>
738	<p>Add more stuff to miscellaneous section.</p>
739	</li>
740	</ul>
741	</div>
742	<div class="SECT2">
743	<hr>
744	<h3 class="SECT2"><a name="COPYRIGHT" id="COPYRIGHT">1.9.
745	Copyright</a></h3>
746	<p>Copyright © 2001 by Pradeep Padala.</p>
747	<p>Permission is hereby granted, free of charge, to any person
748	obtaining a copy of this software and associated documentation
749	files (the "Software"), to deal in the Software without
750	restriction, including without limitation the rights to use, copy,
751	modify, merge, publish, distribute, distribute with modifications,
752	sublicense, and/or sell copies of the Software, and to permit
753	persons to whom the Software is furnished to do so, subject to the
754	following conditions:</p>
755	<p>The above copyright notice and this permission notice shall be
756	included in all copies or substantial portions of the Software.</p>
757	<p>THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
758	EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
759	MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
760	NONINFRINGEMENT. IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE
761	LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
762	ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
763	CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
764	SOFTWARE.</p>
765	<p>Except as contained in this notice, the name(s) of the above
766	copyright holders shall not be used in advertising or otherwise to
767	promote the sale, use or other dealings in this Software without
768	prior written authorization.</p>
769	</div>
770	</div>
771	<div class="SECT1">
772	<hr>
773	<h2 class="SECT1"><a name="HELLOWORLD" id="HELLOWORLD">2. Hello
774	World !!!</a></h2>
775	<p>Welcome to the world of curses. Before we plunge into the
776	library and look into its various features, let's write a simple
777	program and say hello to the world.</p>
778	<div class="SECT2">
779	<hr>
780	<h3 class="SECT2"><a name="COMPILECURSES" id="COMPILECURSES">2.1.
781	Compiling With the NCURSES Library</a></h3>
782	<p>To use ncurses library functions, you have to include ncurses.h
783	in your programs. To link the program with ncurses the flag
784	-lncurses should be added.</p>
785	<table border="0" bgcolor="#E0E0E0" width="100%">
786	<tr>
787	<td>
788	<pre class="PROGRAMLISTING">
789	<font color="#000000"> #include <ncurses.h>
790	.
791	.
792	.
793
794	compile and link: gcc <program file> -lncurses</font>
795	</pre></td>
796	</tr>
797	</table>
798	<div class="EXAMPLE"><a name="BHW" id="BHW"></a>
799	<p><b>Example 1. The Hello World !!! Program</b></p>
800	<table border="0" bgcolor="#E0E0E0" width="100%">
801	<tr>
802	<td>
803	<pre class="PROGRAMLISTING">
804	<font color="#000000"><span class=
805	"INLINEMEDIAOBJECT">#include <ncurses.h>
806
807	int main()
808	{
809	initscr(); /* Start curses mode */
810	printw("Hello World !!!"); /* Print Hello World */
811	refresh(); /* Print it on to the real screen */
812	getch(); /* Wait for user input */
813	endwin(); /* End curses mode */
814
815	return 0;
816	}</span></font>
817	</pre></td>
818	</tr>
819	</table>
820	</div>
821	</div>
822	<div class="SECT2">
823	<hr>
824	<h3 class="SECT2"><a name="DISSECTION" id="DISSECTION">2.2.
825	Dissection</a></h3>
826	<p>The above program prints "Hello World !!!" to the screen and
827	exits. This program shows how to initialize curses and do screen
828	manipulation and end curses mode. Let's dissect it line by
829	line.</p>
830	<div class="SECT3">
831	<hr>
832	<h4 class="SECT3"><a name="ABOUT-INITSCR" id="ABOUT-INITSCR">2.2.1.
833	About initscr()</a></h4>
834	<p>The function initscr() initializes the terminal in curses mode.
835	In some implementations, it clears the screen and presents a blank
836	screen. To do any screen manipulation using curses package this has
837	to be called first. This function initializes the curses system and
838	allocates memory for our present window (called <var class=
839	"LITERAL">stdscr</var>) and some other data-structures. Under
840	extreme cases this function might fail due to insufficient memory
841	to allocate memory for curses library's data structures.</p>
842	<p>After this is done, we can do a variety of initializations to
843	customize our curses settings. These details will be explained
844	<a href="#INIT">later</a> .</p>
845	</div>
846	<div class="SECT3">
847	<hr>
848	<h4 class="SECT3"><a name="MYST-REFRESH" id="MYST-REFRESH">2.2.2.
849	The mysterious refresh()</a></h4>
850	<p>The next line printw prints the string "Hello World !!!" on to
851	the screen. This function is analogous to normal printf in all
852	respects except that it prints the data on a window called stdscr
853	at the current (y,x) co-ordinates. Since our present co-ordinates
854	are at 0,0 the string is printed at the left hand corner of the
855	window.</p>
856	<p>This brings us to that mysterious refresh(). Well, when we
857	called printw the data is actually written to an imaginary window,
858	which is not updated on the screen yet. The job of printw is to
859	update a few flags and data structures and write the data to a
860	buffer corresponding to stdscr. In order to show it on the screen,
861	we need to call refresh() and tell the curses system to dump the
862	contents on the screen.</p>
863	<p>The philosophy behind all this is to allow the programmer to do
864	multiple updates on the imaginary screen or windows and do a
865	refresh once all his screen update is done. refresh() checks the
866	window and updates only the portion which has been changed. This
867	improves performance and offers greater flexibility too. But, it is
868	sometimes frustrating to beginners. A common mistake committed by
869	beginners is to forget to call refresh() after they did some update
870	through printw() class of functions. I still forget to add it
871	sometimes :-)</p>
872	</div>
873	<div class="SECT3">
874	<hr>
875	<h4 class="SECT3"><a name="ABOUT-ENDWIN" id="ABOUT-ENDWIN">2.2.3.
876	About endwin()</a></h4>
877	<p>And finally don't forget to end the curses mode. Otherwise your
878	terminal might behave strangely after the program quits. endwin()
879	frees the memory taken by curses sub-system and its data structures
880	and puts the terminal in normal mode. This function must be called
881	after you are done with the curses mode.</p>
882	</div>
883	</div>
884	</div>
885	<div class="SECT1">
886	<hr>
887	<h2 class="SECT1"><a name="GORY" id="GORY">3. The Gory
888	Details</a></h2>
889	<p>Now that we have seen how to write a simple curses program let's
890	get into the details. There are many functions that help customize
891	what you see on screen and many features which can be put to full
892	use.</p>
893	<p>Here we go...</p>
894	</div>
895	<div class="SECT1">
896	<hr>
897	<h2 class="SECT1"><a name="INIT" id="INIT">4.
898	Initialization</a></h2>
899	<p>We now know that to initialize curses system the function
900	initscr() has to be called. There are functions which can be called
901	after this initialization to customize our curses session. We may
902	ask the curses system to set the terminal in raw mode or initialize
903	color or initialize the mouse etc.. Let's discuss some of the
904	functions that are normally called immediately after initscr();</p>
905	<div class="SECT2">
906	<hr>
907	<h3 class="SECT2"><a name="ABOUTINIT" id="ABOUTINIT">4.1.
908	Initialization functions</a></h3>
909	</div>
910	<div class="SECT2">
911	<hr>
912	<h3 class="SECT2"><a name="RAWCBREAK" id="RAWCBREAK">4.2. raw() and
913	cbreak()</a></h3>
914	<p>Normally the terminal driver buffers the characters a user types
915	until a new line or carriage return is encountered. But most
916	programs require that the characters be available as soon as the
917	user types them. The above two functions are used to disable line
918	buffering. The difference between these two functions is in the way
919	control characters like suspend (CTRL-Z), interrupt and quit
920	(CTRL-C) are passed to the program. In the raw() mode these
921	characters are directly passed to the program without generating a
922	signal. In the <var class="LITERAL">cbreak()</var> mode these
923	control characters are interpreted as any other character by the
924	terminal driver. I personally prefer to use raw() as I can exercise
925	greater control over what the user does.</p>
926	</div>
927	<div class="SECT2">
928	<hr>
929	<h3 class="SECT2"><a name="ECHONOECHO" id="ECHONOECHO">4.3. echo()
930	and noecho()</a></h3>
931	<p>These functions control the echoing of characters typed by the
932	user to the terminal. <var class="LITERAL">noecho()</var> switches
933	off echoing. The reason you might want to do this is to gain more
934	control over echoing or to suppress unnecessary echoing while
935	taking input from the user through the getch() etc. functions. Most
936	of the interactive programs call <var class=
937	"LITERAL">noecho()</var> at initialization and do the echoing of
938	characters in a controlled manner. It gives the programmer the
939	flexibility of echoing characters at any place in the window
940	without updating current (y,x) co-ordinates.</p>
941	</div>
942	<div class="SECT2">
943	<hr>
944	<h3 class="SECT2"><a name="KEYPAD" id="KEYPAD">4.4.
945	keypad()</a></h3>
946	<p>This is my favorite initialization function. It enables the
947	reading of function keys like F1, F2, arrow keys etc. Almost every
948	interactive program enables this, as arrow keys are a major part of
949	any User Interface. Do <var class="LITERAL">keypad(stdscr,
950	TRUE)</var> to enable this feature for the regular screen (stdscr).
951	You will learn more about key management in later sections of this
952	document.</p>
953	</div>
954	<div class="SECT2">
955	<hr>
956	<h3 class="SECT2"><a name="HALFDELAY" id="HALFDELAY">4.5.
957	halfdelay()</a></h3>
958	<p>This function, though not used very often, is a useful one at
959	times. halfdelay()is called to enable the half-delay mode, which is
960	similar to the cbreak() mode in that characters typed are
961	immediately available to program. However, it waits for 'X' tenths
962	of a second for input and then returns ERR, if no input is
963	available. 'X' is the timeout value passed to the function
964	halfdelay(). This function is useful when you want to ask the user
965	for input, and if he doesn't respond with in certain time, we can
966	do some thing else. One possible example is a timeout at the
967	password prompt.</p>
968	</div>
969	<div class="SECT2">
970	<hr>
971	<h3 class="SECT2"><a name="MISCINIT" id="MISCINIT">4.6.
972	Miscellaneous Initialization functions</a></h3>
973	<p>There are few more functions which are called at initialization
974	to customize curses behavior. They are not used as extensively as
975	those mentioned above. Some of them are explained where
976	appropriate.</p>
977	</div>
978	<div class="SECT2">
979	<hr>
980	<h3 class="SECT2"><a name="INITEX" id="INITEX">4.7. An
981	Example</a></h3>
982	<p>Let's write a program which will clarify the usage of these
983	functions.</p>
984	<div class="EXAMPLE"><a name="BINFU" id="BINFU"></a>
985	<p><b>Example 2. Initialization Function Usage example</b></p>
986	<table border="0" bgcolor="#E0E0E0" width="100%">
987	<tr>
988	<td>
989	<pre class="PROGRAMLISTING">
990	<font color="#000000"><span class=
991	"INLINEMEDIAOBJECT">#include <ncurses.h>
992
993	int main()
994	{ int ch;
995
996	initscr(); /* Start curses mode */
997	raw(); /* Line buffering disabled */
998	keypad(stdscr, TRUE); /* We get F1, F2 etc.. */
999	noecho(); /* Don't echo() while we do getch */
1000
1001	printw("Type any character to see it in bold\n");
1002	ch = getch(); /* If raw() hadn't been called
1003	* we have to press enter before it
1004	* gets to the program */
1005	if(ch == KEY_F(1)) /* Without keypad enabled this will */
1006	printw("F1 Key pressed");/* not get to us either */
1007	/* Without noecho() some ugly escape
1008	* charachters might have been printed
1009	* on screen */
1010	else
1011	{ printw("The pressed key is ");
1012	attron(A_BOLD);
1013	printw("%c", ch);
1014	attroff(A_BOLD);
1015	}
1016	refresh(); /* Print it on to the real screen */
1017	getch(); /* Wait for user input */
1018	endwin(); /* End curses mode */
1019
1020	return 0;
1021	}</span></font>
1022	</pre></td>
1023	</tr>
1024	</table>
1025	</div>
1026	<p>This program is self-explanatory. But I used functions which
1027	aren't explained yet. The function <var class=
1028	"LITERAL">getch()</var> is used to get a character from user. It is
1029	equivalent to normal <var class="LITERAL">getchar()</var> except
1030	that we can disable the line buffering to avoid <enter> after
1031	input. Look for more about <var class="LITERAL">getch()</var>and
1032	reading keys in the <a href="#KEYS">key management section</a> .
1033	The functions attron and attroff are used to switch some attributes
1034	on and off respectively. In the example I used them to print the
1035	character in bold. These functions are explained in detail
1036	later.</p>
1037	</div>
1038	</div>
1039	<div class="SECT1">
1040	<hr>
1041	<h2 class="SECT1"><a name="AWORDWINDOWS" id="AWORDWINDOWS">5. A
1042	Word about Windows</a></h2>
1043	<p>Before we plunge into the myriad ncurses functions, let me clear
1044	few things about windows. Windows are explained in detail in
1045	following <a href="#WINDOWS">sections</a></p>
1046	<p>A Window is an imaginary screen defined by curses system. A
1047	window does not mean a bordered window which you usually see on
1048	Win9X platforms. When curses is initialized, it creates a default
1049	window named <var class="LITERAL">stdscr</var> which represents
1050	your 80x25 (or the size of window in which you are running) screen.
1051	If you are doing simple tasks like printing few strings, reading
1052	input etc., you can safely use this single window for all of your
1053	purposes. You can also create windows and call functions which
1054	explicitly work on the specified window.</p>
1055	<p>For example, if you call</p>
1056	<table border="0" bgcolor="#E0E0E0" width="100%">
1057	<tr>
1058	<td>
1059	<pre class="PROGRAMLISTING">
1060	<font color="#000000"> printw("Hi There !!!");
1061	refresh();</font>
1062	</pre></td>
1063	</tr>
1064	</table>
1065	<p>It prints the string on stdscr at the present cursor position.
1066	Similarly the call to refresh(), works on stdscr only.</p>
1067	<p>Say you have created <a href="#WINDOWS">windows</a> then you
1068	have to call a function with a 'w' added to the usual function.</p>
1069	<table border="0" bgcolor="#E0E0E0" width="100%">
1070	<tr>
1071	<td>
1072	<pre class="PROGRAMLISTING">
1073	<font color="#000000"> wprintw(win, "Hi There !!!");
1074	wrefresh(win);</font>
1075	</pre></td>
1076	</tr>
1077	</table>
1078	<p>As you will see in the rest of the document, naming of functions
1079	follow the same convention. For each function there usually are
1080	three more functions.</p>
1081	<table border="0" bgcolor="#E0E0E0" width="100%">
1082	<tr>
1083	<td>
1084	<pre class="PROGRAMLISTING">
1085	<font color=
1086	"#000000"> printw(string); /* Print on stdscr at present cursor position */
1087	mvprintw(y, x, string);/* Move to (y, x) then print string */
1088	wprintw(win, string); /* Print on window win at present cursor position */
1089	/* in the window */
1090	mvwprintw(win, y, x, string); /* Move to (y, x) relative to window */
1091	/* co-ordinates and then print */</font>
1092	</pre></td>
1093	</tr>
1094	</table>
1095	<p>Usually the w-less functions are macros which expand to
1096	corresponding w-function with stdscr as the window parameter.</p>
1097	</div>
1098	<div class="SECT1">
1099	<hr>
1100	<h2 class="SECT1"><a name="PRINTW" id="PRINTW">6. Output
1101	functions</a></h2>
1102	<p>I guess you can't wait any more to see some action. Back to our
1103	odyssey of curses functions. Now that curses is initialized, let's
1104	interact with world.</p>
1105	<p>There are three classes of functions which you can use to do
1106	output on screen.</p>
1107	<ol type="1">
1108	<li>
1109	<p>addch() class: Print single character with attributes</p>
1110	</li>
1111	<li>
1112	<p>printw() class: Print formatted output similar to printf()</p>
1113	</li>
1114	<li>
1115	<p>addstr() class: Print strings</p>
1116	</li>
1117	</ol>
1118	<p>These functions can be used interchangeably and it's a matter of
1119	style as to which class is used. Let's see each one in detail.</p>
1120	<div class="SECT2">
1121	<hr>
1122	<h3 class="SECT2"><a name="ADDCHCLASS" id="ADDCHCLASS">6.1. addch()
1123	class of functions</a></h3>
1124	<p>These functions put a single character into the current cursor
1125	location and advance the position of the cursor. You can give the
1126	character to be printed but they usually are used to print a
1127	character with some attributes. Attributes are explained in detail
1128	in later <a href="#ATTRIB">sections</a> of the document. If a
1129	character is associated with an attribute(bold, reverse video
1130	etc.), when curses prints the character, it is printed in that
1131	attribute.</p>
1132	<p>In order to combine a character with some attributes, you have
1133	two options:</p>
1134	<ul>
1135	<li>
1136	<p>By OR'ing a single character with the desired attribute macros.
1137	These attribute macros could be found in the header file
1138	<var class="LITERAL">ncurses.h</var>. For example, you want to
1139	print a character ch(of type char) bold and underlined, you would
1140	call addch() as below.</p>
1141	<table border="0" bgcolor="#E0E0E0" width="90%">
1142	<tr>
1143	<td>
1144	<pre class="PROGRAMLISTING">
1145	<font color="#000000"> addch(ch \| A_BOLD \| A_UNDERLINE);</font>
1146	</pre></td>
1147	</tr>
1148	</table>
1149	</li>
1150	<li>
1151	<p>By using functions like <var class=
1152	"LITERAL">attrset(),attron(),attroff()</var>. These functions are
1153	explained in the <a href="#ATTRIB">Attributes</a> section. Briefly,
1154	they manipulate the current attributes of the given window. Once
1155	set, the character printed in the window are associated with the
1156	attributes until it is turned off.</p>
1157	</li>
1158	</ul>
1159	<p>Additionally, <var class="LITERAL">curses</var> provides some
1160	special characters for character-based graphics. You can draw
1161	tables, horizontal or vertical lines, etc. You can find all
1162	avaliable characters in the header file <var class=
1163	"LITERAL">ncurses.h</var>. Try looking for macros beginning with
1164	<var class="LITERAL">ACS_</var> in this file.</p>
1165	</div>
1166	<div class="SECT2">
1167	<hr>
1168	<h3 class="SECT2"><a name="AEN298" id="AEN298">6.2. mvaddch(),
1169	waddch() and mvwaddch()</a></h3>
1170	<p><var class="LITERAL">mvaddch()</var> is used to move the cursor
1171	to a given point, and then print. Thus, the calls:</p>
1172	<table border="0" bgcolor="#E0E0E0" width="100%">
1173	<tr>
1174	<td>
1175	<pre class="PROGRAMLISTING">
1176	<font color=
1177	"#000000"> move(row,col); /* moves the cursor to row<em>th</em> row and col<em>th</em> column */
1178	addch(ch);</font>
1179	</pre></td>
1180	</tr>
1181	</table>
1182	can be replaced by
1183	<table border="0" bgcolor="#E0E0E0" width="100%">
1184	<tr>
1185	<td>
1186	<pre class="PROGRAMLISTING">
1187	<font color="#000000"> mvaddch(row,col,ch);</font>
1188	</pre></td>
1189	</tr>
1190	</table>
1191	<p><var class="LITERAL">waddch()</var> is similar to <var class=
1192	"LITERAL">addch()</var>, except that it adds a character into the
1193	given window. (Note that <var class="LITERAL">addch()</var> adds a
1194	character into the window <var class="LITERAL">stdscr</var>.)</p>
1195	<p>In a similar fashion <var class="LITERAL">mvwaddch()</var>
1196	function is used to add a character into the given window at the
1197	given coordinates.</p>
1198	<p>Now, we are familiar with the basic output function <var class=
1199	"LITERAL">addch()</var>. But, if we want to print a string, it
1200	would be very annoying to print it character by character.
1201	Fortunately, <var class="LITERAL">ncurses</var> provides
1202	<var class="LITERAL">printf</var><em>-like</em> or <var class=
1203	"LITERAL">puts</var><em>-like</em> functions.</p>
1204	</div>
1205	<div class="SECT2">
1206	<hr>
1207	<h3 class="SECT2"><a name="PRINTWCLASS" id="PRINTWCLASS">6.3.
1208	printw() class of functions</a></h3>
1209	<p>These functions are similar to <var class=
1210	"LITERAL">printf()</var> with the added capability of printing at
1211	any position on the screen.</p>
1212	<div class="SECT3">
1213	<hr>
1214	<h4 class="SECT3"><a name="PRINTWMVPRINTW" id=
1215	"PRINTWMVPRINTW">6.3.1. printw() and mvprintw</a></h4>
1216	<p>These two functions work much like <var class=
1217	"LITERAL">printf()</var>. <var class="LITERAL">mvprintw()</var> can
1218	be used to move the cursor to a position and then print. If you
1219	want to move the cursor first and then print using <var class=
1220	"LITERAL">printw()</var> function, use <var class=
1221	"LITERAL">move()</var> first and then use <var class=
1222	"LITERAL">printw()</var> though I see no point why one should avoid
1223	using <var class="LITERAL">mvprintw()</var>, you have the
1224	flexibility to manipulate.</p>
1225	</div>
1226	<div class="SECT3">
1227	<hr>
1228	<h4 class="SECT3"><a name="WPRINTWMVWPRINTW" id=
1229	"WPRINTWMVWPRINTW">6.3.2. wprintw() and mvwprintw</a></h4>
1230	<p>These two functions are similar to above two except that they
1231	print in the corresponding window given as argument.</p>
1232	</div>
1233	<div class="SECT3">
1234	<hr>
1235	<h4 class="SECT3"><a name="VWPRINTW" id="VWPRINTW">6.3.3.
1236	vwprintw()</a></h4>
1237	<p>This function is similar to <var class=
1238	"LITERAL">vprintf()</var>. This can be used when variable number of
1239	arguments are to be printed.</p>
1240	</div>
1241	<div class="SECT3">
1242	<hr>
1243	<h4 class="SECT3"><a name="SIMPLEPRINTWEX" id=
1244	"SIMPLEPRINTWEX">6.3.4. A Simple printw example</a></h4>
1245	<div class="EXAMPLE"><a name="BPREX" id="BPREX"></a>
1246	<p><b>Example 3. A Simple printw example</b></p>
1247	<table border="0" bgcolor="#E0E0E0" width="100%">
1248	<tr>
1249	<td>
1250	<pre class="PROGRAMLISTING">
1251	<font color="#000000"><span class=
1252	"INLINEMEDIAOBJECT">#include <ncurses.h> /* ncurses.h includes stdio.h */
1253	#include <string.h>
1254
1255	int main()
1256	{
1257	char mesg[]="Just a string"; /* message to be appeared on the screen */
1258	int row,col; /* to store the number of rows and *
1259	* the number of colums of the screen */
1260	initscr(); /* start the curses mode */
1261	getmaxyx(stdscr,row,col); /* get the number of rows and columns */
1262	mvprintw(row/2,(col-strlen(mesg))/2,"%s",mesg);
1263	/* print the message at the center of the screen */
1264	mvprintw(row-2,0,"This screen has %d rows and %d columns\n",row,col);
1265	printw("Try resizing your window(if possible) and then run this program again");
1266	refresh();
1267	getch();
1268	endwin();
1269
1270	return 0;
1271	}</span></font>
1272	</pre></td>
1273	</tr>
1274	</table>
1275	</div>
1276	<p>Above program demonstrates how easy it is to use <var class=
1277	"LITERAL">printw</var>. You just feed the coordinates and the
1278	message to be appeared on the screen, then it does what you
1279	want.</p>
1280	<p>The above program introduces us to a new function <var class=
1281	"LITERAL">getmaxyx()</var>, a macro defined in <var class=
1282	"LITERAL">ncurses.h</var>. It gives the number of columns and the
1283	number of rows in a given window. <var class=
1284	"LITERAL">getmaxyx()</var> does this by updating the variables
1285	given to it. Since <var class="LITERAL">getmaxyx()</var> is not a
1286	function we don't pass pointers to it, we just give two integer
1287	variables.</p>
1288	</div>
1289	</div>
1290	<div class="SECT2">
1291	<hr>
1292	<h3 class="SECT2"><a name="ADDSTRCLASS" id="ADDSTRCLASS">6.4.
1293	addstr() class of functions</a></h3>
1294	<p><var class="LITERAL">addstr()</var> is used to put a character
1295	string into a given window. This function is similar to calling
1296	<var class="LITERAL">addch()</var> once for each character in a
1297	given string. This is true for all output functions. There are
1298	other functions from this family such as <var class=
1299	"LITERAL">mvaddstr(),mvwaddstr()</var> and <var class=
1300	"LITERAL">waddstr()</var>, which obey the naming convention of
1301	curses.(e.g. mvaddstr() is similar to the respective calls move()
1302	and then addstr().) Another function of this family is addnstr(),
1303	which takes an integer parameter(say n) additionally. This function
1304	puts at most n characters into the screen. If n is negative, then
1305	the entire string will be added.</p>
1306	</div>
1307	<div class="SECT2">
1308	<hr>
1309	<h3 class="SECT2"><a name="ACAUTION" id="ACAUTION">6.5. A word of
1310	caution</a></h3>
1311	<p>All these functions take y co-ordinate first and then x in their
1312	arguments. A common mistake by beginners is to pass x,y in that
1313	order. If you are doing too many manipulations of (y,x)
1314	co-ordinates, think of dividing the screen into windows and
1315	manipulate each one separately. Windows are explained in the
1316	<a href="#WINDOWS">windows</a> section.</p>
1317	</div>
1318	</div>
1319	<div class="SECT1">
1320	<hr>
1321	<h2 class="SECT1"><a name="SCANW" id="SCANW">7. Input
1322	functions</a></h2>
1323	<p>Well, printing without taking input, is boring. Let's see
1324	functions which allow us to get input from user. These functions
1325	also can be divided into three categories.</p>
1326	<ol type="1">
1327	<li>
1328	<p>getch() class: Get a character</p>
1329	</li>
1330	<li>
1331	<p>scanw() class: Get formatted input</p>
1332	</li>
1333	<li>
1334	<p>getstr() class: Get strings</p>
1335	</li>
1336	</ol>
1337	<div class="SECT2">
1338	<hr>
1339	<h3 class="SECT2"><a name="GETCHCLASS" id="GETCHCLASS">7.1. getch()
1340	class of functions</a></h3>
1341	<p>These functions read a single character from the terminal. But
1342	there are several subtle facts to consider. For example if you
1343	don't use the function cbreak(), curses will not read your input
1344	characters contiguously but will begin read them only after a new
1345	line or an EOF is encountered. In order to avoid this, the cbreak()
1346	function must used so that characters are immediately available to
1347	your program. Another widely used function is noecho(). As the name
1348	suggests, when this function is set (used), the characters that are
1349	keyed in by the user will not show up on the screen. The two
1350	functions cbreak() and noecho() are typical examples of key
1351	management. Functions of this genre are explained in the <a href=
1352	"#KEYS">key management section</a> .</p>
1353	</div>
1354	<div class="SECT2">
1355	<hr>
1356	<h3 class="SECT2"><a name="SCANWCLASS" id="SCANWCLASS">7.2. scanw()
1357	class of functions</a></h3>
1358	<p>These functions are similar to <var class=
1359	"LITERAL">scanf()</var> with the added capability of getting the
1360	input from any location on the screen.</p>
1361	<div class="SECT3">
1362	<hr>
1363	<h4 class="SECT3"><a name="SCANWMVSCANW" id="SCANWMVSCANW">7.2.1.
1364	scanw() and mvscanw</a></h4>
1365	<p>The usage of these functions is similar to that of <var class=
1366	"LITERAL">sscanf()</var>, where the line to be scanned is provided
1367	by <var class="LITERAL">wgetstr()</var> function. That is, these
1368	functions call to <var class="LITERAL">wgetstr()</var>
1369	function(explained below) and uses the resulting line for a
1370	scan.</p>
1371	</div>
1372	<div class="SECT3">
1373	<hr>
1374	<h4 class="SECT3"><a name="WSCANWMVWSCANW" id=
1375	"WSCANWMVWSCANW">7.2.2. wscanw() and mvwscanw()</a></h4>
1376	<p>These are similar to above two functions except that they read
1377	from a window, which is supplied as one of the arguments to these
1378	functions.</p>
1379	</div>
1380	<div class="SECT3">
1381	<hr>
1382	<h4 class="SECT3"><a name="VWSCANW" id="VWSCANW">7.2.3.
1383	vwscanw()</a></h4>
1384	<p>This function is similar to <var class="LITERAL">vscanf()</var>.
1385	This can be used when a variable number of arguments are to be
1386	scanned.</p>
1387	</div>
1388	</div>
1389	<div class="SECT2">
1390	<hr>
1391	<h3 class="SECT2"><a name="GETSTRCLASS" id="GETSTRCLASS">7.3.
1392	getstr() class of functions</a></h3>
1393	<p>These functions are used to get strings from the terminal. In
1394	essence, this function performs the same task as would be achieved
1395	by a series of calls to <var class="LITERAL">getch()</var> until a
1396	newline, carriage return, or end-of-file is received. The resulting
1397	string of characters are pointed to by <var class=
1398	"LITERAL">str</var>, which is a character pointer provided by the
1399	user.</p>
1400	</div>
1401	<div class="SECT2">
1402	<hr>
1403	<h3 class="SECT2"><a name="GETSTREX" id="GETSTREX">7.4. Some
1404	examples</a></h3>
1405	<div class="EXAMPLE"><a name="BSCEX" id="BSCEX"></a>
1406	<p><b>Example 4. A Simple scanw example</b></p>
1407	<table border="0" bgcolor="#E0E0E0" width="100%">
1408	<tr>
1409	<td>
1410	<pre class="PROGRAMLISTING">
1411	<font color="#000000"><span class=
1412	"INLINEMEDIAOBJECT">#include <ncurses.h> /* ncurses.h includes stdio.h */
1413	#include <string.h>
1414
1415	int main()
1416	{
1417	char mesg[]="Enter a string: "; /* message to be appeared on the screen */
1418	char str[80];
1419	int row,col; /* to store the number of rows and *
1420	* the number of colums of the screen */
1421	initscr(); /* start the curses mode */
1422	getmaxyx(stdscr,row,col); /* get the number of rows and columns */
1423	mvprintw(row/2,(col-strlen(mesg))/2,"%s",mesg);
1424	/* print the message at the center of the screen */
1425	getstr(str);
1426	mvprintw(LINES - 2, 0, "You Entered: %s", str);
1427	getch();
1428	endwin();
1429
1430	return 0;
1431	}</span></font>
1432	</pre></td>
1433	</tr>
1434	</table>
1435	</div>
1436	</div>
1437	</div>
1438	<div class="SECT1">
1439	<hr>
1440	<h2 class="SECT1"><a name="ATTRIB" id="ATTRIB">8.
1441	Attributes</a></h2>
1442	<p>We have seen an example of how attributes can be used to print
1443	characters with some special effects. Attributes, when set
1444	prudently, can present information in an easy, understandable
1445	manner. The following program takes a C file as input and prints
1446	the file with comments in bold. Scan through the code.</p>
1447	<div class="EXAMPLE"><a name="BSIAT" id="BSIAT"></a>
1448	<p><b>Example 5. A Simple Attributes example</b></p>
1449	<table border="0" bgcolor="#E0E0E0" width="100%">
1450	<tr>
1451	<td>
1452	<pre class="PROGRAMLISTING">
1453	<font color="#000000"><span class=
1454	"INLINEMEDIAOBJECT">/* pager functionality by Joseph Spainhour" <spainhou@bellsouth.net> */
1455	#include <ncurses.h>
1456	#include <stdlib.h>
1457
1458	int main(int argc, char *argv[])
1459	{
1460	int ch, prev, row, col;
1461	prev = EOF;
1462	FILE *fp;
1463	int y, x;
1464
1465	if(argc != 2)
1466	{
1467	printf("Usage: %s <a c file name>\n", argv[0]);
1468	exit(1);
1469	}
1470	fp = fopen(argv[1], "r");
1471	if(fp == NULL)
1472	{
1473	perror("Cannot open input file");
1474	exit(1);
1475	}
1476	initscr(); /* Start curses mode */
1477	getmaxyx(stdscr, row, col); /* find the boundaries of the screeen */
1478	while((ch = fgetc(fp)) != EOF) /* read the file till we reach the end */
1479	{
1480	getyx(stdscr, y, x); /* get the current curser position */
1481	if(y == (row - 1)) /* are we are at the end of the screen */
1482	{
1483	printw("<-Press Any Key->"); /* tell the user to press a key */
1484	getch();
1485	clear(); /* clear the screen */
1486	move(0, 0); /* start at the beginning of the screen */
1487	}
1488	if(prev == '/' && ch == '') / If it is / and * then only
1489	* switch bold on */
1490	{
1491	attron(A_BOLD); /* cut bold on */
1492	getyx(stdscr, y, x); /* get the current curser position */
1493	move(y, x - 1); /* back up one space */
1494	printw("%c%c", '/', ch); /* The actual printing is done here */
1495	}
1496	else
1497	printw("%c", ch);
1498	refresh();
1499	if(prev == '*' && ch == '/')
1500	attroff(A_BOLD); /* Switch it off once we got *
1501	* and then / */
1502	prev = ch;
1503	}
1504	endwin(); /* End curses mode */
1505	fclose(fp);
1506	return 0;
1507	}</span></font>
1508	</pre></td>
1509	</tr>
1510	</table>
1511	</div>
1512	<p>Don't worry about all those initialization and other crap.
1513	Concentrate on the while loop. It reads each character in the file
1514	and searches for the pattern /*. Once it spots the pattern, it
1515	switches the BOLD attribute on with <var class=
1516	"LITERAL">attron()</var> . When we get the pattern */ it is
1517	switched off by <var class="LITERAL">attroff()</var> .</p>
1518	<p>The above program also introduces us to two useful functions
1519	<var class="LITERAL">getyx()</var> and <var class=
1520	"LITERAL">move()</var>. The first function gets the co-ordinates of
1521	the present cursor into the variables y, x. Since getyx() is a
1522	macro we don't have to pass pointers to variables. The function
1523	<var class="LITERAL">move()</var> moves the cursor to the
1524	co-ordinates given to it.</p>
1525	<p>The above program is really a simple one which doesn't do much.
1526	On these lines one could write a more useful program which reads a
1527	C file, parses it and prints it in different colors. One could even
1528	extend it to other languages as well.</p>
1529	<div class="SECT2">
1530	<hr>
1531	<h3 class="SECT2"><a name="ATTRIBDETAILS" id="ATTRIBDETAILS">8.1.
1532	The details</a></h3>
1533	<p>Let's get into more details of attributes. The functions
1534	<var class="LITERAL">attron(), attroff(), attrset()</var> , and
1535	their sister functions <var class="LITERAL">attr_get()</var> etc..
1536	can be used to switch attributes on/off , get attributes and
1537	produce a colorful display.</p>
1538	<p>The functions attron and attroff take a bit-mask of attributes
1539	and switch them on or off, respectively. The following video
1540	attributes, which are defined in <curses.h> can be passed to
1541	these functions.</p>
1542	<table border="0" bgcolor="#E0E0E0" width="100%">
1543	<tr>
1544	<td>
1545	<pre class="PROGRAMLISTING">
1546	<font color="#000000">
1547	A_NORMAL Normal display (no highlight)
1548	A_STANDOUT Best highlighting mode of the terminal.
1549	A_UNDERLINE Underlining
1550	A_REVERSE Reverse video
1551	A_BLINK Blinking
1552	A_DIM Half bright
1553	A_BOLD Extra bright or bold
1554	A_PROTECT Protected mode
1555	A_INVIS Invisible or blank mode
1556	A_ALTCHARSET Alternate character set
1557	A_CHARTEXT Bit-mask to extract a character
1558	COLOR_PAIR(n) Color-pair number n
1559	</font>
1560	</pre></td>
1561	</tr>
1562	</table>
1563	<p>The last one is the most colorful one :-) Colors are explained
1564	in the <a href="#color" target="_top">next sections</a>.</p>
1565	<p>We can OR(\|) any number of above attributes to get a combined
1566	effect. If you wanted reverse video with blinking characters you
1567	can use</p>
1568	<table border="0" bgcolor="#E0E0E0" width="100%">
1569	<tr>
1570	<td>
1571	<pre class="PROGRAMLISTING">
1572	<font color="#000000"> attron(A_REVERSE \| A_BLINK);</font>
1573	</pre></td>
1574	</tr>
1575	</table>
1576	</div>
1577	<div class="SECT2">
1578	<hr>
1579	<h3 class="SECT2"><a name="ATTRONVSATTRSET" id=
1580	"ATTRONVSATTRSET">8.2. attron() vs attrset()</a></h3>
1581	<p>Then what is the difference between attron() and attrset()?
1582	attrset sets the attributes of window whereas attron just switches
1583	on the attribute given to it. So attrset() fully overrides whatever
1584	attributes the window previously had and sets it to the new
1585	attribute(s). Similarly attroff() just switches off the
1586	attribute(s) given to it as an argument. This gives us the
1587	flexibility of managing attributes easily.But if you use them
1588	carelessly you may loose track of what attributes the window has
1589	and garble the display. This is especially true while managing
1590	menus with colors and highlighting. So decide on a consistent
1591	policy and stick to it. You can always use <var class=
1592	"LITERAL">standend()</var> which is equivalent to <var class=
1593	"LITERAL">attrset(A_NORMAL)</var> which turns off all attributes
1594	and brings you to normal mode.</p>
1595	</div>
1596	<div class="SECT2">
1597	<hr>
1598	<h3 class="SECT2"><a name="ATTR_GET" id="ATTR_GET">8.3.
1599	attr_get()</a></h3>
1600	<p>The function attr_get() gets the current attributes and color
1601	pair of the window. Though we might not use this as often as the
1602	above functions, this is useful in scanning areas of screen. Say we
1603	wanted to do some complex update on screen and we are not sure what
1604	attribute each character is associated with. Then this function can
1605	be used with either attrset or attron to produce the desired
1606	effect.</p>
1607	</div>
1608	<div class="SECT2">
1609	<hr>
1610	<h3 class="SECT2"><a name="ATTR_FUNCS" id="ATTR_FUNCS">8.4. attr_
1611	functions</a></h3>
1612	<p>There are series of functions like attr_set(), attr_on etc..
1613	These are similar to above functions except that they take
1614	parameters of type <var class="LITERAL">attr_t</var>.</p>
1615	</div>
1616	<div class="SECT2">
1617	<hr>
1618	<h3 class="SECT2"><a name="WATTRFUNCS" id="WATTRFUNCS">8.5. wattr
1619	functions</a></h3>
1620	<p>For each of the above functions we have a corresponding function
1621	with 'w' which operates on a particular window. The above functions
1622	operate on stdscr.</p>
1623	</div>
1624	<div class="SECT2">
1625	<hr>
1626	<h3 class="SECT2"><a name="CHGAT" id="CHGAT">8.6. chgat()
1627	functions</a></h3>
1628	<p>The function chgat() is listed in the end of the man page
1629	curs_attr. It actually is a useful one. This function can be used
1630	to set attributes for a group of characters without moving. I mean
1631	it !!! without moving the cursor :-) It changes the attributes of a
1632	given number of characters starting at the current cursor
1633	location.</p>
1634	<p>We can give -1 as the character count to update till end of
1635	line. If you want to change attributes of characters from current
1636	position to end of line, just use this.</p>
1637	<table border="0" bgcolor="#E0E0E0" width="100%">
1638	<tr>
1639	<td>
1640	<pre class="PROGRAMLISTING">
1641	<font color="#000000"> chgat(-1, A_REVERSE, 0, NULL);</font>
1642	</pre></td>
1643	</tr>
1644	</table>
1645	<p>This function is useful when changing attributes for characters
1646	that are already on the screen. Move to the character from which
1647	you want to change and change the attribute.</p>
1648	<p>Other functions wchgat(), mvchgat(), wchgat() behave similarly
1649	except that the w functions operate on the particular window. The
1650	mv functions first move the cursor then perform the work given to
1651	them. Actually chgat is a macro which is replaced by a wchgat()
1652	with stdscr as the window. Most of the "w-less" functions are
1653	macros.</p>
1654	<div class="EXAMPLE"><a name="BWICH" id="BWICH"></a>
1655	<p><b>Example 6. Chgat() Usage example</b></p>
1656	<table border="0" bgcolor="#E0E0E0" width="100%">
1657	<tr>
1658	<td>
1659	<pre class="PROGRAMLISTING">
1660	<font color="#000000"><span class=
1661	"INLINEMEDIAOBJECT">#include <ncurses.h>
1662
1663	int main(int argc, char *argv[])
1664	{ initscr(); /* Start curses mode */
1665	start_color(); /* Start color functionality */
1666
1667	init_pair(1, COLOR_CYAN, COLOR_BLACK);
1668	printw("A Big string which i didn't care to type fully ");
1669	mvchgat(0, 0, -1, A_BLINK, 1, NULL);
1670	/*
1671	* First two parameters specify the position at which to start
1672	* Third parameter number of characters to update. -1 means till
1673	* end of line
1674	* Forth parameter is the normal attribute you wanted to give
1675	* to the charcter
1676	* Fifth is the color index. It is the index given during init_pair()
1677	* use 0 if you didn't want color
1678	* Sixth one is always NULL
1679	*/
1680	refresh();
1681	getch();
1682	endwin(); /* End curses mode */
1683	return 0;
1684	}</span></font>
1685	</pre></td>
1686	</tr>
1687	</table>
1688	</div>
1689	<p>This example also introduces us to the color world of curses.
1690	Colors will be explained in detail later. Use 0 for no color.</p>
1691	</div>
1692	</div>
1693	<div class="SECT1">
1694	<hr>
1695	<h2 class="SECT1"><a name="WINDOWS" id="WINDOWS">9.
1696	Windows</a></h2>
1697	<p>Windows form the most important concept in curses. You have seen
1698	the standard window stdscr above where all the functions implicitly
1699	operated on this window. Now to make design even a simplest GUI,
1700	you need to resort to windows. The main reason you may want to use
1701	windows is to manipulate parts of the screen separately, for better
1702	efficiency, by updating only the windows that need to be changed
1703	and for a better design. I would say the last reason is the most
1704	important in going for windows. You should always strive for a
1705	better and easy-to-manage design in your programs. If you are
1706	writing big, complex GUIs this is of pivotal importance before you
1707	start doing anything.</p>
1708	<div class="SECT2">
1709	<hr>
1710	<h3 class="SECT2"><a name="WINDOWBASICS" id="WINDOWBASICS">9.1. The
1711	basics</a></h3>
1712	<p>A Window can be created by calling the function <var class=
1713	"LITERAL">newwin()</var>. It doesn't create any thing on the screen
1714	actually. It allocates memory for a structure to manipulate the
1715	window and updates the structure with data regarding the window
1716	like it's size, beginy, beginx etc.. Hence in curses, a window is
1717	just an abstraction of an imaginary window, which can be
1718	manipulated independent of other parts of screen. The function
1719	newwin() returns a pointer to structure WINDOW, which can be passed
1720	to window related functions like wprintw() etc.. Finally the window
1721	can be destroyed with delwin(). It will deallocate the memory
1722	associated with the window structure.</p>
1723	</div>
1724	<div class="SECT2">
1725	<hr>
1726	<h3 class="SECT2"><a name="LETBEWINDOW" id="LETBEWINDOW">9.2. Let
1727	there be a Window !!!</a></h3>
1728	<p>What fun is it, if a window is created and we can't see it. So
1729	the fun part begins by displaying the window. The function
1730	<var class="LITERAL">box()</var> can be used to draw a border
1731	around the window. Let's explore these functions in more detail in
1732	this example.</p>
1733	<div class="EXAMPLE"><a name="BWIBO" id="BWIBO"></a>
1734	<p><b>Example 7. Window Border example</b></p>
1735	<table border="0" bgcolor="#E0E0E0" width="100%">
1736	<tr>
1737	<td>
1738	<pre class="PROGRAMLISTING">
1739	<font color="#000000"><span class=
1740	"INLINEMEDIAOBJECT">#include <ncurses.h>
1741
1742
1743	WINDOW *create_newwin(int height, int width, int starty, int startx);
1744	void destroy_win(WINDOW *local_win);
1745
1746	int main(int argc, char *argv[])
1747	{ WINDOW *my_win;
1748	int startx, starty, width, height;
1749	int ch;
1750
1751	initscr(); /* Start curses mode */
1752	cbreak(); /* Line buffering disabled, Pass on
1753	* everty thing to me */
1754	keypad(stdscr, TRUE); /* I need that nifty F1 */
1755
1756	height = 3;
1757	width = 10;
1758	starty = (LINES - height) / 2; /* Calculating for a center placement */
1759	startx = (COLS - width) / 2; /* of the window */
1760	printw("Press F1 to exit");
1761	refresh();
1762	my_win = create_newwin(height, width, starty, startx);
1763
1764	while((ch = getch()) != KEY_F(1))
1765	{ switch(ch)
1766	{ case KEY_LEFT:
1767	destroy_win(my_win);
1768	my_win = create_newwin(height, width, starty,--startx);
1769	break;
1770	case KEY_RIGHT:
1771	destroy_win(my_win);
1772	my_win = create_newwin(height, width, starty,++startx);
1773	break;
1774	case KEY_UP:
1775	destroy_win(my_win);
1776	my_win = create_newwin(height, width, --starty,startx);
1777	break;
1778	case KEY_DOWN:
1779	destroy_win(my_win);
1780	my_win = create_newwin(height, width, ++starty,startx);
1781	break;
1782	}
1783	}
1784
1785	endwin(); /* End curses mode */
1786	return 0;
1787	}
1788
1789	WINDOW *create_newwin(int height, int width, int starty, int startx)
1790	{ WINDOW *local_win;
1791
1792	local_win = newwin(height, width, starty, startx);
1793	box(local_win, 0 , 0); /* 0, 0 gives default characters
1794	* for the vertical and horizontal
1795	* lines */
1796	wrefresh(local_win); /* Show that box */
1797
1798	return local_win;
1799	}
1800
1801	void destroy_win(WINDOW *local_win)
1802	{
1803	/* box(local_win, ' ', ' '); : This won't produce the desired
1804	* result of erasing the window. It will leave it's four corners
1805	* and so an ugly remnant of window.
1806	*/
1807	wborder(local_win, ' ', ' ', ' ',' ',' ',' ',' ',' ');
1808	/* The parameters taken are
1809	* 1. win: the window on which to operate
1810	* 2. ls: character to be used for the left side of the window
1811	* 3. rs: character to be used for the right side of the window
1812	* 4. ts: character to be used for the top side of the window
1813	* 5. bs: character to be used for the bottom side of the window
1814	* 6. tl: character to be used for the top left corner of the window
1815	* 7. tr: character to be used for the top right corner of the window
1816	* 8. bl: character to be used for the bottom left corner of the window
1817	* 9. br: character to be used for the bottom right corner of the window
1818	*/
1819	wrefresh(local_win);
1820	delwin(local_win);
1821	}</span></font>
1822	</pre></td>
1823	</tr>
1824	</table>
1825	</div>
1826	</div>
1827	<div class="SECT2">
1828	<hr>
1829	<h3 class="SECT2"><a name="BORDEREXEXPL" id="BORDEREXEXPL">9.3.
1830	Explanation</a></h3>
1831	<p>Don't scream. I know it's a big example. But I have to explain
1832	some important things here :-). This program creates a rectangular
1833	window that can be moved with left, right, up, down arrow keys. It
1834	repeatedly creates and destroys windows as user press a key. Don't
1835	go beyond the screen limits. Checking for those limits is left as
1836	an exercise for the reader. Let's dissect it by line by line.</p>
1837	<p>The <var class="LITERAL">create_newwin()</var> function creates
1838	a window with <var class="LITERAL">newwin()</var> and displays a
1839	border around it with box. The function <var class=
1840	"LITERAL">destroy_win()</var> first erases the window from screen
1841	by painting a border with ' ' character and then calling
1842	<var class="LITERAL">delwin()</var> to deallocate memory related to
1843	it. Depending on the key the user presses, starty or startx is
1844	changed and a new window is created.</p>
1845	<p>In the destroy_win, as you can see, I used wborder instead of
1846	box. The reason is written in the comments (You missed it. I know.
1847	Read the code :-)). wborder draws a border around the window with
1848	the characters given to it as the 4 corner points and the 4 lines.
1849	To put it clearly, if you have called wborder as below:</p>
1850	<table border="0" bgcolor="#E0E0E0" width="100%">
1851	<tr>
1852	<td>
1853	<pre class="PROGRAMLISTING">
1854	<font color=
1855	"#000000"> wborder(win, '\|', '\|', '-', '-', '+', '+', '+', '+');</font>
1856	</pre></td>
1857	</tr>
1858	</table>
1859	<p>it produces some thing like</p>
1860	<table border="0" bgcolor="#E0E0E0" width="100%">
1861	<tr>
1862	<td>
1863	<pre class="PROGRAMLISTING">
1864	<font color="#000000"> +------------+
1865	\| \|
1866	\| \|
1867	\| \|
1868	\| \|
1869	\| \|
1870	\| \|
1871	+------------+</font>
1872	</pre></td>
1873	</tr>
1874	</table>
1875	</div>
1876	<div class="SECT2">
1877	<hr>
1878	<h3 class="SECT2"><a name="OTHERSTUFF" id="OTHERSTUFF">9.4. The
1879	other stuff in the example</a></h3>
1880	<p>You can also see in the above examples, that I have used the
1881	variables COLS, LINES which are initialized to the screen sizes
1882	after initscr(). They can be useful in finding screen dimensions
1883	and finding the center co-ordinate of the screen as above. The
1884	function <var class="LITERAL">getch()</var> as usual gets the key
1885	from keyboard and according to the key it does the corresponding
1886	work. This type of switch- case is very common in any GUI based
1887	programs.</p>
1888	</div>
1889	<div class="SECT2">
1890	<hr>
1891	<h3 class="SECT2"><a name="OTHERBORDERFUNCS" id=
1892	"OTHERBORDERFUNCS">9.5. Other Border functions</a></h3>
1893	<p>Above program is grossly inefficient in that with each press of
1894	a key, a window is destroyed and another is created. So let's write
1895	a more efficient program which uses other border related
1896	functions.</p>
1897	<p>The following program uses <var class="LITERAL">mvhline()</var>
1898	and <var class="LITERAL">mvvline()</var> to achieve similar effect.
1899	These two functions are simple. They create a horizontal or
1900	vertical line of the specified length at the specified
1901	position.</p>
1902	<div class="EXAMPLE"><a name="BOTBO" id="BOTBO"></a>
1903	<p><b>Example 8. More border functions</b></p>
1904	<table border="0" bgcolor="#E0E0E0" width="100%">
1905	<tr>
1906	<td>
1907	<pre class="PROGRAMLISTING">
1908	<font color="#000000"><span class=
1909	"INLINEMEDIAOBJECT">#include <ncurses.h>
1910
1911	typedef struct _win_border_struct {
1912	chtype ls, rs, ts, bs,
1913	tl, tr, bl, br;
1914	}WIN_BORDER;
1915
1916	typedef struct _WIN_struct {
1917
1918	int startx, starty;
1919	int height, width;
1920	WIN_BORDER border;
1921	}WIN;
1922
1923	void init_win_params(WIN *p_win);
1924	void print_win_params(WIN *p_win);
1925	void create_box(WIN *win, bool flag);
1926
1927	int main(int argc, char *argv[])
1928	{ WIN win;
1929	int ch;
1930
1931	initscr(); /* Start curses mode */
1932	start_color(); /* Start the color functionality */
1933	cbreak(); /* Line buffering disabled, Pass on
1934	* everty thing to me */
1935	keypad(stdscr, TRUE); /* I need that nifty F1 */
1936	noecho();
1937	init_pair(1, COLOR_CYAN, COLOR_BLACK);
1938
1939	/* Initialize the window parameters */
1940	init_win_params(&win);
1941	print_win_params(&win);
1942
1943	attron(COLOR_PAIR(1));
1944	printw("Press F1 to exit");
1945	refresh();
1946	attroff(COLOR_PAIR(1));
1947
1948	create_box(&win, TRUE);
1949	while((ch = getch()) != KEY_F(1))
1950	{ switch(ch)
1951	{ case KEY_LEFT:
1952	create_box(&win, FALSE);
1953	--win.startx;
1954	create_box(&win, TRUE);
1955	break;
1956	case KEY_RIGHT:
1957	create_box(&win, FALSE);
1958	++win.startx;
1959	create_box(&win, TRUE);
1960	break;
1961	case KEY_UP:
1962	create_box(&win, FALSE);
1963	--win.starty;
1964	create_box(&win, TRUE);
1965	break;
1966	case KEY_DOWN:
1967	create_box(&win, FALSE);
1968	++win.starty;
1969	create_box(&win, TRUE);
1970	break;
1971	}
1972	}
1973	endwin(); /* End curses mode */
1974	return 0;
1975	}
1976	void init_win_params(WIN *p_win)
1977	{
1978	p_win->height = 3;
1979	p_win->width = 10;
1980	p_win->starty = (LINES - p_win->height)/2;
1981	p_win->startx = (COLS - p_win->width)/2;
1982
1983	p_win->border.ls = '\|';
1984	p_win->border.rs = '\|';
1985	p_win->border.ts = '-';
1986	p_win->border.bs = '-';
1987	p_win->border.tl = '+';
1988	p_win->border.tr = '+';
1989	p_win->border.bl = '+';
1990	p_win->border.br = '+';
1991
1992	}
1993	void print_win_params(WIN *p_win)
1994	{
1995	#ifdef _DEBUG
1996	mvprintw(25, 0, "%d %d %d %d", p_win->startx, p_win->starty,
1997	p_win->width, p_win->height);
1998	refresh();
1999	#endif
2000	}
2001	void create_box(WIN *p_win, bool flag)
2002	{ int i, j;
2003	int x, y, w, h;
2004
2005	x = p_win->startx;
2006	y = p_win->starty;
2007	w = p_win->width;
2008	h = p_win->height;
2009
2010	if(flag == TRUE)
2011	{ mvaddch(y, x, p_win->border.tl);
2012	mvaddch(y, x + w, p_win->border.tr);
2013	mvaddch(y + h, x, p_win->border.bl);
2014	mvaddch(y + h, x + w, p_win->border.br);
2015	mvhline(y, x + 1, p_win->border.ts, w - 1);
2016	mvhline(y + h, x + 1, p_win->border.bs, w - 1);
2017	mvvline(y + 1, x, p_win->border.ls, h - 1);
2018	mvvline(y + 1, x + w, p_win->border.rs, h - 1);
2019
2020	}
2021	else
2022	for(j = y; j <= y + h; ++j)
2023	for(i = x; i <= x + w; ++i)
2024	mvaddch(j, i, ' ');
2025
2026	refresh();
2027
2028	}</span></font>
2029	</pre></td>
2030	</tr>
2031	</table>
2032	</div>
2033	</div>
2034	</div>
2035	<div class="SECT1">
2036	<hr>
2037	<h2 class="SECT1"><a name="COLOR" id="COLOR">10. Colors</a></h2>
2038	<div class="SECT2">
2039	<h3 class="SECT2"><a name="COLORBASICS" id="COLORBASICS">10.1. The
2040	basics</a></h3>
2041	<p>Life seems dull with no colors. Curses has a nice mechanism to
2042	handle colors. Let's get into the thick of the things with a small
2043	program.</p>
2044	<div class="EXAMPLE"><a name="BSICO" id="BSICO"></a>
2045	<p><b>Example 9. A Simple Color example</b></p>
2046	<table border="0" bgcolor="#E0E0E0" width="100%">
2047	<tr>
2048	<td>
2049	<pre class="PROGRAMLISTING">
2050	<font color="#000000"><span class=
2051	"INLINEMEDIAOBJECT">#include <ncurses.h>
2052
2053	void print_in_middle(WINDOW win, int starty, int startx, int width, char string);
2054	int main(int argc, char *argv[])
2055	{ initscr(); /* Start curses mode */
2056	if(has_colors() == FALSE)
2057	{ endwin();
2058	printf("Your terminal does not support color\n");
2059	exit(1);
2060	}
2061	start_color(); /* Start color */
2062	init_pair(1, COLOR_RED, COLOR_BLACK);
2063
2064	attron(COLOR_PAIR(1));
2065	print_in_middle(stdscr, LINES / 2, 0, 0, "Viola !!! In color ...");
2066	attroff(COLOR_PAIR(1));
2067	getch();
2068	endwin();
2069	}
2070	void print_in_middle(WINDOW win, int starty, int startx, int width, char string)
2071	{ int length, x, y;
2072	float temp;
2073
2074	if(win == NULL)
2075	win = stdscr;
2076	getyx(win, y, x);
2077	if(startx != 0)
2078	x = startx;
2079	if(starty != 0)
2080	y = starty;
2081	if(width == 0)
2082	width = 80;
2083
2084	length = strlen(string);
2085	temp = (width - length)/ 2;
2086	x = startx + (int)temp;
2087	mvwprintw(win, y, x, "%s", string);
2088	refresh();
2089	}
2090	</span></font>
2091	</pre></td>
2092	</tr>
2093	</table>
2094	</div>
2095	<p>As you can see, to start using color, you should first call the
2096	function <var class="LITERAL">start_color()</var>. After that, you
2097	can use color capabilities of your terminals using various
2098	functions. To find out whether a terminal has color capabilities or
2099	not, you can use <var class="LITERAL">has_colors()</var> function,
2100	which returns FALSE if the terminal does not support color.</p>
2101	<p>Curses initializes all the colors supported by terminal when
2102	start_color() is called. These can be accessed by the define
2103	constants like <var class="LITERAL">COLOR_BLACK</var> etc. Now to
2104	actually start using colors, you have to define pairs. Colors are
2105	always used in pairs. That means you have to use the function
2106	<var class="LITERAL">init_pair()</var> to define the foreground and
2107	background for the pair number you give. After that that pair
2108	number can be used as a normal attribute with <var class=
2109	"LITERAL">COLOR_PAIR()</var>function. This may seem to be
2110	cumbersome at first. But this elegant solution allows us to manage
2111	color pairs very easily. To appreciate it, you have to look into
2112	the the source code of "dialog", a utility for displaying dialog
2113	boxes from shell scripts. The developers have defined foreground
2114	and background combinations for all the colors they might need and
2115	initialized at the beginning. This makes it very easy to set
2116	attributes just by accessing a pair which we already have defined
2117	as a constant.</p>
2118	<p>The following colors are defined in <var class=
2119	"LITERAL">curses.h</var>. You can use these as parameters for
2120	various color functions.</p>
2121	<table border="0" bgcolor="#E0E0E0" width="100%">
2122	<tr>
2123	<td>
2124	<pre class="PROGRAMLISTING">
2125	<font color="#000000"> COLOR_BLACK 0
2126	COLOR_RED 1
2127	COLOR_GREEN 2
2128	COLOR_YELLOW 3
2129	COLOR_BLUE 4
2130	COLOR_MAGENTA 5
2131	COLOR_CYAN 6
2132	COLOR_WHITE 7</font>
2133	</pre></td>
2134	</tr>
2135	</table>
2136	</div>
2137	<div class="SECT2">
2138	<hr>
2139	<h3 class="SECT2"><a name="CHANGECOLORDEFS" id=
2140	"CHANGECOLORDEFS">10.2. Changing Color Definitions</a></h3>
2141	<p>The function <var class="LITERAL">init_color()</var>can be used
2142	to change the rgb values for the colors defined by curses
2143	initially. Say you wanted to lighten the intensity of red color by
2144	a minuscule. Then you can use this function as</p>
2145	<table border="0" bgcolor="#E0E0E0" width="100%">
2146	<tr>
2147	<td>
2148	<pre class="PROGRAMLISTING">
2149	<font color="#000000"> init_color(COLOR_RED, 700, 0, 0);
2150	/* param 1 : color name
2151	* param 2, 3, 4 : rgb content min = 0, max = 1000 */</font>
2152	</pre></td>
2153	</tr>
2154	</table>
2155	<p>If your terminal cannot change the color definitions, the
2156	function returns ERR. The function <var class=
2157	"LITERAL">can_change_color()</var> can be used to find out whether
2158	the terminal has the capability of changing color content or not.
2159	The rgb content is scaled from 0 to 1000. Initially RED color is
2160	defined with content 1000(r), 0(g), 0(b).</p>
2161	</div>
2162	<div class="SECT2">
2163	<hr>
2164	<h3 class="SECT2"><a name="COLORCONTENT" id="COLORCONTENT">10.3.
2165	Color Content</a></h3>
2166	<p>The functions <var class="LITERAL">color_content()</var> and
2167	<var class="LITERAL">pair_content()</var> can be used to find the
2168	color content and foreground, background combination for the
2169	pair.</p>
2170	</div>
2171	</div>
2172	<div class="SECT1">
2173	<hr>
2174	<h2 class="SECT1"><a name="KEYS" id="KEYS">11. Interfacing with the
2175	key board</a></h2>
2176	<div class="SECT2">
2177	<h3 class="SECT2"><a name="KEYSBASICS" id="KEYSBASICS">11.1. The
2178	Basics</a></h3>
2179	<p>No GUI is complete without a strong user interface and to
2180	interact with the user, a curses program should be sensitive to key
2181	presses or the mouse actions done by the user. Let's deal with the
2182	keys first.</p>
2183	<p>As you have seen in almost all of the above examples, it's very
2184	easy to get key input from the user. A simple way of getting key
2185	presses is to use <var class="LITERAL">getch()</var> function. The
2186	cbreak mode should be enabled to read keys when you are interested
2187	in reading individual key hits rather than complete lines of text
2188	(which usually end with a carriage return). keypad should be
2189	enabled to get the Functions keys, arrow keys etc. See the
2190	initialization section for details.</p>
2191	<p><var class="LITERAL">getch()</var> returns an integer
2192	corresponding to the key pressed. If it is a normal character, the
2193	integer value will be equivalent to the character. Otherwise it
2194	returns a number which can be matched with the constants defined in
2195	<var class="LITERAL">curses.h</var>. For example if the user
2196	presses F1, the integer returned is 265. This can be checked using
2197	the macro KEY_F() defined in curses.h. This makes reading keys
2198	portable and easy to manage.</p>
2199	<p>For example, if you call getch() like this</p>
2200	<table border="0" bgcolor="#E0E0E0" width="100%">
2201	<tr>
2202	<td>
2203	<pre class="PROGRAMLISTING">
2204	<font color="#000000"> int ch;
2205
2206	ch = getch();</font>
2207	</pre></td>
2208	</tr>
2209	</table>
2210	<p>getch() will wait for the user to press a key, (unless you
2211	specified a timeout) and when user presses a key, the corresponding
2212	integer is returned. Then you can check the value returned with the
2213	constants defined in curses.h to match against the keys you
2214	want.</p>
2215	<p>The following code piece will do that job.</p>
2216	<table border="0" bgcolor="#E0E0E0" width="100%">
2217	<tr>
2218	<td>
2219	<pre class="PROGRAMLISTING">
2220	<font color="#000000"> if(ch == KEY_LEFT)
2221	printw("Left arrow is pressed\n");</font>
2222	</pre></td>
2223	</tr>
2224	</table>
2225	<p>Let's write a small program which creates a menu which can be
2226	navigated by up and down arrows.</p>
2227	</div>
2228	<div class="SECT2">
2229	<hr>
2230	<h3 class="SECT2"><a name="SIMPLEKEYEX" id="SIMPLEKEYEX">11.2. A
2231	Simple Key Usage example</a></h3>
2232	<div class="EXAMPLE"><a name="BSIKE" id="BSIKE"></a>
2233	<p><b>Example 10. A Simple Key Usage example</b></p>
2234	<table border="0" bgcolor="#E0E0E0" width="100%">
2235	<tr>
2236	<td>
2237	<pre class="PROGRAMLISTING">
2238	<font color="#000000"><span class=
2239	"INLINEMEDIAOBJECT">#include <stdio.h>
2240	#include <ncurses.h>
2241
2242	#define WIDTH 30
2243	#define HEIGHT 10
2244
2245	int startx = 0;
2246	int starty = 0;
2247
2248	char *choices[] = {
2249	"Choice 1",
2250	"Choice 2",
2251	"Choice 3",
2252	"Choice 4",
2253	"Exit",
2254	};
2255	int n_choices = sizeof(choices) / sizeof(char *);
2256	void print_menu(WINDOW *menu_win, int highlight);
2257
2258	int main()
2259	{ WINDOW *menu_win;
2260	int highlight = 1;
2261	int choice = 0;
2262	int c;
2263
2264	initscr();
2265	clear();
2266	noecho();
2267	cbreak(); /* Line buffering disabled. pass on everything */
2268	startx = (80 - WIDTH) / 2;
2269	starty = (24 - HEIGHT) / 2;
2270
2271	menu_win = newwin(HEIGHT, WIDTH, starty, startx);
2272	keypad(menu_win, TRUE);
2273	mvprintw(0, 0, "Use arrow keys to go up and down, Press enter to select a choice");
2274	refresh();
2275	print_menu(menu_win, highlight);
2276	while(1)
2277	{ c = wgetch(menu_win);
2278	switch(c)
2279	{ case KEY_UP:
2280	if(highlight == 1)
2281	highlight = n_choices;
2282	else
2283	--highlight;
2284	break;
2285	case KEY_DOWN:
2286	if(highlight == n_choices)
2287	highlight = 1;
2288	else
2289	++highlight;
2290	break;
2291	case 10:
2292	choice = highlight;
2293	break;
2294	default:
2295	mvprintw(24, 0, "Charcter pressed is = %3d Hopefully it can be printed as '%c'", c, c);
2296	refresh();
2297	break;
2298	}
2299	print_menu(menu_win, highlight);
2300	if(choice != 0) /* User did a choice come out of the infinite loop */
2301	break;
2302	}
2303	mvprintw(23, 0, "You chose choice %d with choice string %s\n", choice, choices[choice - 1]);
2304	clrtoeol();
2305	refresh();
2306	endwin();
2307	return 0;
2308	}
2309
2310
2311	void print_menu(WINDOW *menu_win, int highlight)
2312	{
2313	int x, y, i;
2314
2315	x = 2;
2316	y = 2;
2317	box(menu_win, 0, 0);
2318	for(i = 0; i < n_choices; ++i)
2319	{ if(highlight == i + 1) /* High light the present choice */
2320	{ wattron(menu_win, A_REVERSE);
2321	mvwprintw(menu_win, y, x, "%s", choices[i]);
2322	wattroff(menu_win, A_REVERSE);
2323	}
2324	else
2325	mvwprintw(menu_win, y, x, "%s", choices[i]);
2326	++y;
2327	}
2328	wrefresh(menu_win);
2329	}
2330	</span></font>
2331	</pre></td>
2332	</tr>
2333	</table>
2334	</div>
2335	</div>
2336	</div>
2337	<div class="SECT1">
2338	<hr>
2339	<h2 class="SECT1"><a name="MOUSE" id="MOUSE">12. Interfacing with
2340	the mouse</a></h2>
2341	<p>Now that you have seen how to get keys, lets do the same thing
2342	from mouse. Usually each UI allows the user to interact with both
2343	keyboard and mouse.</p>
2344	<div class="SECT2">
2345	<hr>
2346	<h3 class="SECT2"><a name="MOUSEBASICS" id="MOUSEBASICS">12.1. The
2347	Basics</a></h3>
2348	<p>Before you do any thing else, the events you want to receive
2349	have to be enabled with <var class="LITERAL">mousemask()</var>.</p>
2350	<table border="0" bgcolor="#E0E0E0" width="100%">
2351	<tr>
2352	<td>
2353	<pre class="PROGRAMLISTING">
2354	<font color=
2355	"#000000"> mousemask( mmask_t newmask, /* The events you want to listen to */
2356	mmask_t oldmask) / The old events mask */</font>
2357	</pre></td>
2358	</tr>
2359	</table>
2360	<p>The first parameter to above function is a bit mask of events
2361	you would like to listen. By default, all the events are turned
2362	off. The bit mask <var class="LITERAL">ALL_MOUSE_EVENTS</var> can
2363	be used to get all the events.</p>
2364	<p>The following are all the event masks:</p>
2365	<table border="0" bgcolor="#E0E0E0" width="100%">
2366	<tr>
2367	<td>
2368	<pre class="PROGRAMLISTING">
2369	<font color="#000000"> Name Description
2370	---------------------------------------------------------------------
2371	BUTTON1_PRESSED mouse button 1 down
2372	BUTTON1_RELEASED mouse button 1 up
2373	BUTTON1_CLICKED mouse button 1 clicked
2374	BUTTON1_DOUBLE_CLICKED mouse button 1 double clicked
2375	BUTTON1_TRIPLE_CLICKED mouse button 1 triple clicked
2376	BUTTON2_PRESSED mouse button 2 down
2377	BUTTON2_RELEASED mouse button 2 up
2378	BUTTON2_CLICKED mouse button 2 clicked
2379	BUTTON2_DOUBLE_CLICKED mouse button 2 double clicked
2380	BUTTON2_TRIPLE_CLICKED mouse button 2 triple clicked
2381	BUTTON3_PRESSED mouse button 3 down
2382	BUTTON3_RELEASED mouse button 3 up
2383	BUTTON3_CLICKED mouse button 3 clicked
2384	BUTTON3_DOUBLE_CLICKED mouse button 3 double clicked
2385	BUTTON3_TRIPLE_CLICKED mouse button 3 triple clicked
2386	BUTTON4_PRESSED mouse button 4 down
2387	BUTTON4_RELEASED mouse button 4 up
2388	BUTTON4_CLICKED mouse button 4 clicked
2389	BUTTON4_DOUBLE_CLICKED mouse button 4 double clicked
2390	BUTTON4_TRIPLE_CLICKED mouse button 4 triple clicked
2391	BUTTON_SHIFT shift was down during button state change
2392	BUTTON_CTRL control was down during button state change
2393	BUTTON_ALT alt was down during button state change
2394	ALL_MOUSE_EVENTS report all button state changes
2395	REPORT_MOUSE_POSITION report mouse movement</font>
2396	</pre></td>
2397	</tr>
2398	</table>
2399	</div>
2400	<div class="SECT2">
2401	<hr>
2402	<h3 class="SECT2"><a name="GETTINGEVENTS" id="GETTINGEVENTS">12.2.
2403	Getting the events</a></h3>
2404	<p>Once a class of mouse events have been enabled, getch() class of
2405	functions return KEY_MOUSE every time some mouse event happens.
2406	Then the mouse event can be retrieved with <var class=
2407	"LITERAL">getmouse()</var>.</p>
2408	<p>The code approximately looks like this:</p>
2409	<table border="0" bgcolor="#E0E0E0" width="100%">
2410	<tr>
2411	<td>
2412	<pre class="PROGRAMLISTING">
2413	<font color="#000000"> MEVENT event;
2414
2415	ch = getch();
2416	if(ch == KEY_MOUSE)
2417	if(getmouse(&event) == OK)
2418	. /* Do some thing with the event */
2419	.
2420	.</font>
2421	</pre></td>
2422	</tr>
2423	</table>
2424	<p>getmouse() returns the event into the pointer given to it. It's
2425	a structure which contains</p>
2426	<table border="0" bgcolor="#E0E0E0" width="100%">
2427	<tr>
2428	<td>
2429	<pre class="PROGRAMLISTING">
2430	<font color="#000000"> typedef struct
2431	{
2432	short id; /* ID to distinguish multiple devices */
2433	int x, y, z; /* event coordinates */
2434	mmask_t bstate; /* button state bits */
2435	} </font>
2436	</pre></td>
2437	</tr>
2438	</table>
2439	<p>The <var class="LITERAL">bstate</var> is the main variable we
2440	are interested in. It tells the button state of the mouse.</p>
2441	<p>Then with a code snippet like the following, we can find out
2442	what happened.</p>
2443	<table border="0" bgcolor="#E0E0E0" width="100%">
2444	<tr>
2445	<td>
2446	<pre class="PROGRAMLISTING">
2447	<font color="#000000"> if(event.bstate & BUTTON1_PRESSED)
2448	printw("Left Button Pressed");</font>
2449	</pre></td>
2450	</tr>
2451	</table>
2452	</div>
2453	<div class="SECT2">
2454	<hr>
2455	<h3 class="SECT2"><a name="MOUSETOGETHER" id="MOUSETOGETHER">12.3.
2456	Putting it all Together</a></h3>
2457	<p>That's pretty much interfacing with mouse. Let's create the same
2458	menu and enable mouse interaction. To make things simpler, key
2459	handling is removed.</p>
2460	<div class="EXAMPLE"><a name="BMOME" id="BMOME"></a>
2461	<p><b>Example 11. Access the menu with mouse !!!</b></p>
2462	<table border="0" bgcolor="#E0E0E0" width="100%">
2463	<tr>
2464	<td>
2465	<pre class="PROGRAMLISTING">
2466	<font color="#000000"><span class=
2467	"INLINEMEDIAOBJECT">#include <ncurses.h>
2468
2469	#define WIDTH 30
2470	#define HEIGHT 10
2471
2472	int startx = 0;
2473	int starty = 0;
2474
2475	char *choices[] = { "Choice 1",
2476	"Choice 2",
2477	"Choice 3",
2478	"Choice 4",
2479	"Exit",
2480	};
2481
2482	int n_choices = sizeof(choices) / sizeof(char *);
2483
2484	void print_menu(WINDOW *menu_win, int highlight);
2485	void report_choice(int mouse_x, int mouse_y, int *p_choice);
2486
2487	int main()
2488	{ int c, choice = 0;
2489	WINDOW *menu_win;
2490	MEVENT event;
2491
2492	/* Initialize curses */
2493	initscr();
2494	clear();
2495	noecho();
2496	cbreak(); //Line buffering disabled. pass on everything
2497
2498	/* Try to put the window in the middle of screen */
2499	startx = (80 - WIDTH) / 2;
2500	starty = (24 - HEIGHT) / 2;
2501
2502	attron(A_REVERSE);
2503	mvprintw(23, 1, "Click on Exit to quit (Works best in a virtual console)");
2504	refresh();
2505	attroff(A_REVERSE);
2506
2507	/* Print the menu for the first time */
2508	menu_win = newwin(HEIGHT, WIDTH, starty, startx);
2509	print_menu(menu_win, 1);
2510	/* Get all the mouse events */
2511	mousemask(ALL_MOUSE_EVENTS, NULL);
2512
2513	while(1)
2514	{ c = wgetch(menu_win);
2515	switch(c)
2516	{ case KEY_MOUSE:
2517	if(getmouse(&event) == OK)
2518	{ /* When the user clicks left mouse button */
2519	if(event.bstate & BUTTON1_PRESSED)
2520	{ report_choice(event.x + 1, event.y + 1, &choice);
2521	if(choice == -1) //Exit chosen
2522	goto end;
2523	mvprintw(22, 1, "Choice made is : %d String Chosen is \"%10s\"", choice, choices[choice - 1]);
2524	refresh();
2525	}
2526	}
2527	print_menu(menu_win, choice);
2528	break;
2529	}
2530	}
2531	end:
2532	endwin();
2533	return 0;
2534	}
2535
2536
2537	void print_menu(WINDOW *menu_win, int highlight)
2538	{
2539	int x, y, i;
2540
2541	x = 2;
2542	y = 2;
2543	box(menu_win, 0, 0);
2544	for(i = 0; i < n_choices; ++i)
2545	{ if(highlight == i + 1)
2546	{ wattron(menu_win, A_REVERSE);
2547	mvwprintw(menu_win, y, x, "%s", choices[i]);
2548	wattroff(menu_win, A_REVERSE);
2549	}
2550	else
2551	mvwprintw(menu_win, y, x, "%s", choices[i]);
2552	++y;
2553	}
2554	wrefresh(menu_win);
2555	}
2556
2557	/* Report the choice according to mouse position */
2558	void report_choice(int mouse_x, int mouse_y, int *p_choice)
2559	{ int i,j, choice;
2560
2561	i = startx + 2;
2562	j = starty + 3;
2563
2564	for(choice = 0; choice < n_choices; ++choice)
2565	if(mouse_y == j + choice && mouse_x >= i && mouse_x <= i + strlen(choices[choice]))
2566	{ if(choice == n_choices - 1)
2567	*p_choice = -1;
2568	else
2569	*p_choice = choice + 1;
2570	break;
2571	}
2572	}</span></font>
2573	</pre></td>
2574	</tr>
2575	</table>
2576	</div>
2577	</div>
2578	<div class="SECT2">
2579	<hr>
2580	<h3 class="SECT2"><a name="MISCMOUSEFUNCS" id=
2581	"MISCMOUSEFUNCS">12.4. Miscellaneous Functions</a></h3>
2582	<p>The functions mouse_trafo() and wmouse_trafo() can be used to
2583	convert to mouse co-ordinates to screen relative co-ordinates. See
2584	curs_mouse(3X) man page for details.</p>
2585	<p>The mouseinterval function sets the maximum time (in thousands
2586	of a second) that can elapse between press and release events in
2587	order for them to be recognized as a click. This function returns
2588	the previous interval value. The default is one fifth of a
2589	second.</p>
2590	</div>
2591	</div>
2592	<div class="SECT1">
2593	<hr>
2594	<h2 class="SECT1"><a name="SCREEN" id="SCREEN">13. Screen
2595	Manipulation</a></h2>
2596	<p>In this section, we will look into some functions, which allow
2597	us to manage the screen efficiently and to write some fancy
2598	programs. This is especially important in writing games.</p>
2599	<div class="SECT2">
2600	<hr>
2601	<h3 class="SECT2"><a name="GETYX" id="GETYX">13.1. getyx()
2602	functions</a></h3>
2603	<p>The function <var class="LITERAL">getyx()</var> can be used to
2604	find out the present cursor co-ordinates. It will fill the values
2605	of x and y co-ordinates in the arguments given to it. Since getyx()
2606	is a macro you don't have to pass the address of the variables. It
2607	can be called as</p>
2608	<table border="0" bgcolor="#E0E0E0" width="100%">
2609	<tr>
2610	<td>
2611	<pre class="PROGRAMLISTING">
2612	<font color="#000000"> getyx(win, y, x);
2613	/* win: window pointer
2614	* y, x: y, x co-ordinates will be put into this variables
2615	*/</font>
2616	</pre></td>
2617	</tr>
2618	</table>
2619	<p>The function getparyx() gets the beginning co-ordinates of the
2620	sub window relative to the main window. This is some times useful
2621	to update a sub window. When designing fancy stuff like writing
2622	multiple menus, it becomes difficult to store the menu positions,
2623	their first option co-ordinates etc. A simple solution to this
2624	problem, is to create menus in sub windows and later find the
2625	starting co-ordinates of the menus by using getparyx().</p>
2626	<p>The functions getbegyx() and getmaxyx() store current window's
2627	beginning and maximum co-ordinates. These functions are useful in
2628	the same way as above in managing the windows and sub windows
2629	effectively.</p>
2630	</div>
2631	<div class="SECT2">
2632	<hr>
2633	<h3 class="SECT2"><a name="SCREENDUMP" id="SCREENDUMP">13.2. Screen
2634	Dumping</a></h3>
2635	<p>While writing games, some times it becomes necessary to store
2636	the state of the screen and restore it back to the same state. The
2637	function scr_dump() can be used to dump the screen contents to a
2638	file given as an argument. Later it can be restored by scr_restore
2639	function. These two simple functions can be used effectively to
2640	maintain a fast moving game with changing scenarios.</p>
2641	</div>
2642	<div class="SECT2">
2643	<hr>
2644	<h3 class="SECT2"><a name="WINDOWDUMP" id="WINDOWDUMP">13.3. Window
2645	Dumping</a></h3>
2646	<p>To store and restore windows, the functions <var class=
2647	"LITERAL">putwin()</var> and <var class="LITERAL">getwin()</var>
2648	can be used. <var class="LITERAL">putwin()</var> puts the present
2649	window state into a file, which can be later restored by
2650	<var class="LITERAL">getwin()</var>.</p>
2651	<p>The function <var class="LITERAL">copywin()</var> can be used to
2652	copy a window completely onto another window. It takes the source
2653	and destination windows as parameters and according to the
2654	rectangle specified, it copies the rectangular region from source
2655	to destination window. It's last parameter specifies whether to
2656	overwrite or just overlay the contents on to the destination
2657	window. If this argument is true, then the copying is
2658	non-destructive.</p>
2659	</div>
2660	</div>
2661	<div class="SECT1">
2662	<hr>
2663	<h2 class="SECT1"><a name="MISC" id="MISC">14. Miscellaneous
2664	features</a></h2>
2665	<p>Now you know enough features to write a good curses program,
2666	with all bells and whistles. There are some miscellaneous functions
2667	which are useful in various cases. Let's go headlong into some of
2668	those.</p>
2669	<div class="SECT2">
2670	<hr>
2671	<h3 class="SECT2"><a name="CURSSET" id="CURSSET">14.1.
2672	curs_set()</a></h3>
2673	<p>This function can be used to make the cursor invisible. The
2674	parameter to this function should be</p>
2675	<table border="0" bgcolor="#E0E0E0" width="100%">
2676	<tr>
2677	<td>
2678	<pre class="PROGRAMLISTING">
2679	<font color="#000000"> 0 : invisible or
2680	1 : normal or
2681	2 : very visible.</font>
2682	</pre></td>
2683	</tr>
2684	</table>
2685	</div>
2686	<div class="SECT2">
2687	<hr>
2688	<h3 class="SECT2"><a name="TEMPLEAVE" id="TEMPLEAVE">14.2.
2689	Temporarily Leaving Curses mode</a></h3>
2690	<p>Some times you may want to get back to cooked mode (normal line
2691	buffering mode) temporarily. In such a case you will first need to
2692	save the tty modes with a call to <var class=
2693	"LITERAL">def_prog_mode()</var> and then call <var class=
2694	"LITERAL">endwin()</var> to end the curses mode. This will leave
2695	you in the original tty mode. To get back to curses once you are
2696	done, call <var class="LITERAL">reset_prog_mode()</var> . This
2697	function returns the tty to the state stored by <var class=
2698	"LITERAL">def_prog_mode()</var>. Then do refresh(), and you are
2699	back to the curses mode. Here is an example showing the sequence of
2700	things to be done.</p>
2701	<div class="EXAMPLE"><a name="BTELE" id="BTELE"></a>
2702	<p><b>Example 12. Temporarily Leaving Curses Mode</b></p>
2703	<table border="0" bgcolor="#E0E0E0" width="100%">
2704	<tr>
2705	<td>
2706	<pre class="PROGRAMLISTING">
2707	<font color="#000000"><span class=
2708	"INLINEMEDIAOBJECT">#include <ncurses.h>
2709
2710	int main()
2711	{
2712	initscr(); /* Start curses mode */
2713	printw("Hello World !!!\n"); /* Print Hello World */
2714	refresh(); /* Print it on to the real screen */
2715	def_prog_mode(); /* Save the tty modes */
2716	endwin(); /* End curses mode temporarily */
2717	system("/bin/sh"); /* Do whatever you like in cooked mode */
2718	reset_prog_mode(); /* Return to the previous tty mode*/
2719	/* stored by def_prog_mode() */
2720	refresh(); /* Do refresh() to restore the */
2721	/* Screen contents */
2722	printw("Another String\n"); /* Back to curses use the full */
2723	refresh(); /* capabilities of curses */
2724	endwin(); /* End curses mode */
2725
2726	return 0;
2727	}</span></font>
2728	</pre></td>
2729	</tr>
2730	</table>
2731	</div>
2732	</div>
2733	<div class="SECT2">
2734	<hr>
2735	<h3 class="SECT2"><a name="ACSVARS" id="ACSVARS">14.3. ACS_
2736	variables</a></h3>
2737	<p>If you have ever programmed in DOS, you know about those nifty
2738	characters in extended character set. They are printable only on
2739	some terminals. NCURSES functions like <var class=
2740	"LITERAL">box()</var> use these characters. All these variables
2741	start with ACS meaning alternative character set. You might have
2742	noticed me using these characters in some of the programs above.
2743	Here's an example showing all the characters.</p>
2744	<div class="EXAMPLE"><a name="BACSVARS" id="BACSVARS"></a>
2745	<p><b>Example 13. ACS Variables Example</b></p>
2746	<table border="0" bgcolor="#E0E0E0" width="100%">
2747	<tr>
2748	<td>
2749	<pre class="PROGRAMLISTING">
2750	<font color="#000000"><span class=
2751	"INLINEMEDIAOBJECT">#include <ncurses.h>
2752
2753	int main()
2754	{
2755	initscr();
2756
2757	printw("Upper left corner "); addch(ACS_ULCORNER); printw("\n");
2758	printw("Lower left corner "); addch(ACS_LLCORNER); printw("\n");
2759	printw("Lower right corner "); addch(ACS_LRCORNER); printw("\n");
2760	printw("Tee pointing right "); addch(ACS_LTEE); printw("\n");
2761	printw("Tee pointing left "); addch(ACS_RTEE); printw("\n");
2762	printw("Tee pointing up "); addch(ACS_BTEE); printw("\n");
2763	printw("Tee pointing down "); addch(ACS_TTEE); printw("\n");
2764	printw("Horizontal line "); addch(ACS_HLINE); printw("\n");
2765	printw("Vertical line "); addch(ACS_VLINE); printw("\n");
2766	printw("Large Plus or cross over "); addch(ACS_PLUS); printw("\n");
2767	printw("Scan Line 1 "); addch(ACS_S1); printw("\n");
2768	printw("Scan Line 3 "); addch(ACS_S3); printw("\n");
2769	printw("Scan Line 7 "); addch(ACS_S7); printw("\n");
2770	printw("Scan Line 9 "); addch(ACS_S9); printw("\n");
2771	printw("Diamond "); addch(ACS_DIAMOND); printw("\n");
2772	printw("Checker board (stipple) "); addch(ACS_CKBOARD); printw("\n");
2773	printw("Degree Symbol "); addch(ACS_DEGREE); printw("\n");
2774	printw("Plus/Minus Symbol "); addch(ACS_PLMINUS); printw("\n");
2775	printw("Bullet "); addch(ACS_BULLET); printw("\n");
2776	printw("Arrow Pointing Left "); addch(ACS_LARROW); printw("\n");
2777	printw("Arrow Pointing Right "); addch(ACS_RARROW); printw("\n");
2778	printw("Arrow Pointing Down "); addch(ACS_DARROW); printw("\n");
2779	printw("Arrow Pointing Up "); addch(ACS_UARROW); printw("\n");
2780	printw("Board of squares "); addch(ACS_BOARD); printw("\n");
2781	printw("Lantern Symbol "); addch(ACS_LANTERN); printw("\n");
2782	printw("Solid Square Block "); addch(ACS_BLOCK); printw("\n");
2783	printw("Less/Equal sign "); addch(ACS_LEQUAL); printw("\n");
2784	printw("Greater/Equal sign "); addch(ACS_GEQUAL); printw("\n");
2785	printw("Pi "); addch(ACS_PI); printw("\n");
2786	printw("Not equal "); addch(ACS_NEQUAL); printw("\n");
2787	printw("UK pound sign "); addch(ACS_STERLING); printw("\n");
2788
2789	refresh();
2790	getch();
2791	endwin();
2792
2793	return 0;
2794	}</span></font>
2795	</pre></td>
2796	</tr>
2797	</table>
2798	</div>
2799	</div>
2800	</div>
2801	<div class="SECT1">
2802	<hr>
2803	<h2 class="SECT1"><a name="OTHERLIB" id="OTHERLIB">15. Other
2804	libraries</a></h2>
2805	<p>Apart from the curses library, there are few text mode
2806	libraries, which provide more functionality and a lot of features.
2807	The following sections explain three standard libraries which are
2808	usually distributed along with curses.</p>
2809	</div>
2810	<div class="SECT1">
2811	<hr>
2812	<h2 class="SECT1"><a name="PANELS" id="PANELS">16. Panel
2813	Library</a></h2>
2814	<p>Now that you are proficient in curses, you wanted to do some
2815	thing big. You created a lot of overlapping windows to give a
2816	professional windows-type look. Unfortunately, it soon becomes
2817	difficult to manage these. The multiple refreshes, updates plunge
2818	you into a nightmare. The overlapping windows create blotches,
2819	whenever you forget to refresh the windows in the proper order.</p>
2820	<p>Don't despair. There's an elegant solution provided in panels
2821	library. In the words of developers of ncurses</p>
2822	<p><em>When your interface design is such that windows may dive
2823	deeper into the visibility stack or pop to the top at runtime, the
2824	resulting book-keeping can be tedious and difficult to get right.
2825	Hence the panels library.</em></p>
2826	<p>If you have lot of overlapping windows, then panels library is
2827	the way to go. It obviates the need of doing series of
2828	wnoutrefresh(), doupdate() and relieves the burden of doing it
2829	correctly(bottom up). The library maintains information about the
2830	order of windows, their overlapping and update the screen properly.
2831	So why wait? Let's take a close peek into panels.</p>
2832	<div class="SECT2">
2833	<hr>
2834	<h3 class="SECT2"><a name="PANELBASICS" id="PANELBASICS">16.1. The
2835	Basics</a></h3>
2836	<p>Panel object is a window that is implicitly treated as part of a
2837	deck including all other panel objects. The deck is treated as a
2838	stack with the top panel being completely visible and the other
2839	panels may or may not be obscured according to their positions. So
2840	the basic idea is to create a stack of overlapping panels and use
2841	panels library to display them correctly. There is a function
2842	similar to refresh() which, when called , displays panels in the
2843	correct order. Functions are provided to hide or show panels, move
2844	panels, change its size etc.. The overlapping problem is managed by
2845	the panels library during all the calls to these functions.</p>
2846	<p>The general flow of a panel program goes like this:</p>
2847	<ol type="1">
2848	<li>
2849	<p>Create the windows (with newwin()) to be attached to the
2850	panels.</p>
2851	</li>
2852	<li>
2853	<p>Create panels with the chosen visibility order. Stack them up
2854	according to the desired visibility. The function new_panel() is
2855	used to created panels.</p>
2856	</li>
2857	<li>
2858	<p>Call update_panels() to write the panels to the virtual screen
2859	in correct visibility order. Do a doupdate() to show it on the
2860	screen.</p>
2861	</li>
2862	<li>
2863	<p>Mainpulate the panels with show_panel(), hide_panel(),
2864	move_panel() etc. Make use of helper functions like panel_hidden()
2865	and panel_window(). Make use of user pointer to store custom data
2866	for a panel. Use the functions set_panel_userptr() and
2867	panel_userptr() to set and get the user pointer for a panel.</p>
2868	</li>
2869	<li>
2870	<p>When you are done with the panel use del_panel() to delete the
2871	panel.</p>
2872	</li>
2873	</ol>
2874	<p>Let's make the concepts clear, with some programs. The following
2875	is a simple program which creates 3 overlapping panels and shows
2876	them on the screen.</p>
2877	</div>
2878	<div class="SECT2">
2879	<hr>
2880	<h3 class="SECT2"><a name="COMPILEPANELS" id="COMPILEPANELS">16.2.
2881	Compiling With the Panels Library</a></h3>
2882	<p>To use panels library functions, you have to include panel.h and
2883	to link the program with panels library the flag -lpanel should be
2884	added along with -lncurses in that order.</p>
2885	<table border="0" bgcolor="#E0E0E0" width="100%">
2886	<tr>
2887	<td>
2888	<pre class="PROGRAMLISTING">
2889	<font color="#000000"> #include <panel.h>
2890	.
2891	.
2892	.
2893
2894	compile and link: gcc <program file> -lpanel -lncurses</font>
2895	</pre></td>
2896	</tr>
2897	</table>
2898	<div class="EXAMPLE"><a name="PPASI" id="PPASI"></a>
2899	<p><b>Example 14. Panel basics</b></p>
2900	<table border="0" bgcolor="#E0E0E0" width="100%">
2901	<tr>
2902	<td>
2903	<pre class="PROGRAMLISTING">
2904	<font color="#000000"><span class=
2905	"INLINEMEDIAOBJECT">#include <panel.h>
2906
2907	int main()
2908	{ WINDOW *my_wins[3];
2909	PANEL *my_panels[3];
2910	int lines = 10, cols = 40, y = 2, x = 4, i;
2911
2912	initscr();
2913	cbreak();
2914	noecho();
2915
2916	/* Create windows for the panels */
2917	my_wins[0] = newwin(lines, cols, y, x);
2918	my_wins[1] = newwin(lines, cols, y + 1, x + 5);
2919	my_wins[2] = newwin(lines, cols, y + 2, x + 10);
2920
2921	/*
2922	* Create borders around the windows so that you can see the effect
2923	* of panels
2924	*/
2925	for(i = 0; i < 3; ++i)
2926	box(my_wins[i], 0, 0);
2927
2928	/* Attach a panel to each window / / Order is bottom up */
2929	my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
2930	my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
2931	my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
2932
2933	/* Update the stacking order. 2nd panel will be on top */
2934	update_panels();
2935
2936	/* Show it on the screen */
2937	doupdate();
2938
2939	getch();
2940	endwin();
2941	}
2942	</span></font>
2943	</pre></td>
2944	</tr>
2945	</table>
2946	</div>
2947	<p>As you can see, above program follows a simple flow as
2948	explained. The windows are created with newwin() and then they are
2949	attached to panels with new_panel(). As we attach one panel after
2950	another, the stack of panels gets updated. To put them on screen
2951	update_panels() and doupdate() are called.</p>
2952	</div>
2953	<div class="SECT2">
2954	<hr>
2955	<h3 class="SECT2"><a name="PANELBROWSING" id="PANELBROWSING">16.3.
2956	Panel Window Browsing</a></h3>
2957	<p>A slightly complicated example is given below. This program
2958	creates 3 windows which can be cycled through using tab. Have a
2959	look at the code.</p>
2960	<div class="EXAMPLE"><a name="PPABR" id="PPABR"></a>
2961	<p><b>Example 15. Panel Window Browsing Example</b></p>
2962	<table border="0" bgcolor="#E0E0E0" width="100%">
2963	<tr>
2964	<td>
2965	<pre class="PROGRAMLISTING">
2966	<font color="#000000"><span class=
2967	"INLINEMEDIAOBJECT">#include <panel.h>
2968
2969	#define NLINES 10
2970	#define NCOLS 40
2971
2972	void init_wins(WINDOW **wins, int n);
2973	void win_show(WINDOW win, char label, int label_color);
2974	void print_in_middle(WINDOW win, int starty, int startx, int width, char string, chtype color);
2975
2976	int main()
2977	{ WINDOW *my_wins[3];
2978	PANEL *my_panels[3];
2979	PANEL *top;
2980	int ch;
2981
2982	/* Initialize curses */
2983	initscr();
2984	start_color();
2985	cbreak();
2986	noecho();
2987	keypad(stdscr, TRUE);
2988
2989	/* Initialize all the colors */
2990	init_pair(1, COLOR_RED, COLOR_BLACK);
2991	init_pair(2, COLOR_GREEN, COLOR_BLACK);
2992	init_pair(3, COLOR_BLUE, COLOR_BLACK);
2993	init_pair(4, COLOR_CYAN, COLOR_BLACK);
2994
2995	init_wins(my_wins, 3);
2996
2997	/* Attach a panel to each window / / Order is bottom up */
2998	my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
2999	my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
3000	my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
3001
3002	/* Set up the user pointers to the next panel */
3003	set_panel_userptr(my_panels[0], my_panels[1]);
3004	set_panel_userptr(my_panels[1], my_panels[2]);
3005	set_panel_userptr(my_panels[2], my_panels[0]);
3006
3007	/* Update the stacking order. 2nd panel will be on top */
3008	update_panels();
3009
3010	/* Show it on the screen */
3011	attron(COLOR_PAIR(4));
3012	mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)");
3013	attroff(COLOR_PAIR(4));
3014	doupdate();
3015
3016	top = my_panels[2];
3017	while((ch = getch()) != KEY_F(1))
3018	{ switch(ch)
3019	{ case 9:
3020	top = (PANEL *)panel_userptr(top);
3021	top_panel(top);
3022	break;
3023	}
3024	update_panels();
3025	doupdate();
3026	}
3027	endwin();
3028	return 0;
3029	}
3030
3031	/* Put all the windows */
3032	void init_wins(WINDOW **wins, int n)
3033	{ int x, y, i;
3034	char label[80];
3035
3036	y = 2;
3037	x = 10;
3038	for(i = 0; i < n; ++i)
3039	{ wins[i] = newwin(NLINES, NCOLS, y, x);
3040	sprintf(label, "Window Number %d", i + 1);
3041	win_show(wins[i], label, i + 1);
3042	y += 3;
3043	x += 7;
3044	}
3045	}
3046
3047	/* Show the window with a border and a label */
3048	void win_show(WINDOW win, char label, int label_color)
3049	{ int startx, starty, height, width;
3050
3051	getbegyx(win, starty, startx);
3052	getmaxyx(win, height, width);
3053
3054	box(win, 0, 0);
3055	mvwaddch(win, 2, 0, ACS_LTEE);
3056	mvwhline(win, 2, 1, ACS_HLINE, width - 2);
3057	mvwaddch(win, 2, width - 1, ACS_RTEE);
3058
3059	print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color));
3060	}
3061
3062	void print_in_middle(WINDOW win, int starty, int startx, int width, char string, chtype color)
3063	{ int length, x, y;
3064	float temp;
3065
3066	if(win == NULL)
3067	win = stdscr;
3068	getyx(win, y, x);
3069	if(startx != 0)
3070	x = startx;
3071	if(starty != 0)
3072	y = starty;
3073	if(width == 0)
3074	width = 80;
3075
3076	length = strlen(string);
3077	temp = (width - length)/ 2;
3078	x = startx + (int)temp;
3079	wattron(win, color);
3080	mvwprintw(win, y, x, "%s", string);
3081	wattroff(win, color);
3082	refresh();
3083	}</span></font>
3084	</pre></td>
3085	</tr>
3086	</table>
3087	</div>
3088	</div>
3089	<div class="SECT2">
3090	<hr>
3091	<h3 class="SECT2"><a name="USERPTRUSING" id="USERPTRUSING">16.4.
3092	Using User Pointers</a></h3>
3093	<p>In the above example I used user pointers to find out the next
3094	window in the cycle. We can attach custom information to the panel
3095	by specifying a user pointer, which can point to any information
3096	you want to store. In this case I stored the pointer to the next
3097	panel in the cycle. User pointer for a panel can be set with the
3098	function <var class="LITERAL">set_panel_userptr()</var>. It can be
3099	accessed using the function <var class=
3100	"LITERAL">panel_userptr()</var> which will return the user pointer
3101	for the panel given as argument. After finding the next panel in
3102	the cycle It's brought to the top by the function top_panel(). This
3103	function brings the panel given as argument to the top of the panel
3104	stack.</p>
3105	</div>
3106	<div class="SECT2">
3107	<hr>
3108	<h3 class="SECT2"><a name="PANELMOVERESIZE" id=
3109	"PANELMOVERESIZE">16.5. Moving and Resizing Panels</a></h3>
3110	<p>The function <var class="LITERAL">move_panel()</var> can be used
3111	to move a panel to the desired location. It does not change the
3112	position of the panel in the stack. Make sure that you use
3113	move_panel() instead mvwin() on the window associated with the
3114	panel.</p>
3115	<p>Resizing a panel is slightly complex. There is no straight
3116	forward function just to resize the window associated with a panel.
3117	A solution to resize a panel is to create a new window with the
3118	desired sizes, change the window associated with the panel using
3119	replace_panel(). Don't forget to delete the old window. The window
3120	associated with a panel can be found by using the function
3121	panel_window().</p>
3122	<p>The following program shows these concepts, in supposedly simple
3123	program. You can cycle through the window with <TAB> as
3124	usual. To resize or move the active panel press 'r' for resize 'm'
3125	for moving. Then use arrow keys to resize or move it to the desired
3126	way and press enter to end your resizing or moving. This example
3127	makes use of user data to get the required data to do the
3128	operations.</p>
3129	<div class="EXAMPLE"><a name="PPARE" id="PPARE"></a>
3130	<p><b>Example 16. Panel Moving and Resizing example</b></p>
3131	<table border="0" bgcolor="#E0E0E0" width="100%">
3132	<tr>
3133	<td>
3134	<pre class="PROGRAMLISTING">
3135	<font color="#000000"><span class=
3136	"INLINEMEDIAOBJECT">#include <panel.h>
3137
3138	typedef struct _PANEL_DATA {
3139	int x, y, w, h;
3140	char label[80];
3141	int label_color;
3142	PANEL *next;
3143	}PANEL_DATA;
3144
3145	#define NLINES 10
3146	#define NCOLS 40
3147
3148	void init_wins(WINDOW **wins, int n);
3149	void win_show(WINDOW win, char label, int label_color);
3150	void print_in_middle(WINDOW win, int starty, int startx, int width, char string, chtype color);
3151	void set_user_ptrs(PANEL **panels, int n);
3152
3153	int main()
3154	{ WINDOW *my_wins[3];
3155	PANEL *my_panels[3];
3156	PANEL_DATA *top;
3157	PANEL *stack_top;
3158	WINDOW temp_win, old_win;
3159	int ch;
3160	int newx, newy, neww, newh;
3161	int size = FALSE, move = FALSE;
3162
3163	/* Initialize curses */
3164	initscr();
3165	start_color();
3166	cbreak();
3167	noecho();
3168	keypad(stdscr, TRUE);
3169
3170	/* Initialize all the colors */
3171	init_pair(1, COLOR_RED, COLOR_BLACK);
3172	init_pair(2, COLOR_GREEN, COLOR_BLACK);
3173	init_pair(3, COLOR_BLUE, COLOR_BLACK);
3174	init_pair(4, COLOR_CYAN, COLOR_BLACK);
3175
3176	init_wins(my_wins, 3);
3177
3178	/* Attach a panel to each window / / Order is bottom up */
3179	my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
3180	my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
3181	my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
3182
3183	set_user_ptrs(my_panels, 3);
3184	/* Update the stacking order. 2nd panel will be on top */
3185	update_panels();
3186
3187	/* Show it on the screen */
3188	attron(COLOR_PAIR(4));
3189	mvprintw(LINES - 3, 0, "Use 'm' for moving, 'r' for resizing");
3190	mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)");
3191	attroff(COLOR_PAIR(4));
3192	doupdate();
3193
3194	stack_top = my_panels[2];
3195	top = (PANEL_DATA *)panel_userptr(stack_top);
3196	newx = top->x;
3197	newy = top->y;
3198	neww = top->w;
3199	newh = top->h;
3200	while((ch = getch()) != KEY_F(1))
3201	{ switch(ch)
3202	{ case 9: /* Tab */
3203	top = (PANEL_DATA *)panel_userptr(stack_top);
3204	top_panel(top->next);
3205	stack_top = top->next;
3206	top = (PANEL_DATA *)panel_userptr(stack_top);
3207	newx = top->x;
3208	newy = top->y;
3209	neww = top->w;
3210	newh = top->h;
3211	break;
3212	case 'r': /* Re-Size*/
3213	size = TRUE;
3214	attron(COLOR_PAIR(4));
3215	mvprintw(LINES - 4, 0, "Entered Resizing :Use Arrow Keys to resize and press <ENTER> to end resizing");
3216	refresh();
3217	attroff(COLOR_PAIR(4));
3218	break;
3219	case 'm': /* Move */
3220	attron(COLOR_PAIR(4));
3221	mvprintw(LINES - 4, 0, "Entered Moving: Use Arrow Keys to Move and press <ENTER> to end moving");
3222	refresh();
3223	attroff(COLOR_PAIR(4));
3224	move = TRUE;
3225	break;
3226	case KEY_LEFT:
3227	if(size == TRUE)
3228	{ --newx;
3229	++neww;
3230	}
3231	if(move == TRUE)
3232	--newx;
3233	break;
3234	case KEY_RIGHT:
3235	if(size == TRUE)
3236	{ ++newx;
3237	--neww;
3238	}
3239	if(move == TRUE)
3240	++newx;
3241	break;
3242	case KEY_UP:
3243	if(size == TRUE)
3244	{ --newy;
3245	++newh;
3246	}
3247	if(move == TRUE)
3248	--newy;
3249	break;
3250	case KEY_DOWN:
3251	if(size == TRUE)
3252	{ ++newy;
3253	--newh;
3254	}
3255	if(move == TRUE)
3256	++newy;
3257	break;
3258	case 10: /* Enter */
3259	move(LINES - 4, 0);
3260	clrtoeol();
3261	refresh();
3262	if(size == TRUE)
3263	{ old_win = panel_window(stack_top);
3264	temp_win = newwin(newh, neww, newy, newx);
3265	replace_panel(stack_top, temp_win);
3266	win_show(temp_win, top->label, top->label_color);
3267	delwin(old_win);
3268	size = FALSE;
3269	}
3270	if(move == TRUE)
3271	{ move_panel(stack_top, newy, newx);
3272	move = FALSE;
3273	}
3274	break;
3275
3276	}
3277	attron(COLOR_PAIR(4));
3278	mvprintw(LINES - 3, 0, "Use 'm' for moving, 'r' for resizing");
3279	mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)");
3280	attroff(COLOR_PAIR(4));
3281	refresh();
3282	update_panels();
3283	doupdate();
3284	}
3285	endwin();
3286	return 0;
3287	}
3288
3289	/* Put all the windows */
3290	void init_wins(WINDOW **wins, int n)
3291	{ int x, y, i;
3292	char label[80];
3293
3294	y = 2;
3295	x = 10;
3296	for(i = 0; i < n; ++i)
3297	{ wins[i] = newwin(NLINES, NCOLS, y, x);
3298	sprintf(label, "Window Number %d", i + 1);
3299	win_show(wins[i], label, i + 1);
3300	y += 3;
3301	x += 7;
3302	}
3303	}
3304
3305	/* Set the PANEL_DATA structures for individual panels */
3306	void set_user_ptrs(PANEL **panels, int n)
3307	{ PANEL_DATA *ptrs;
3308	WINDOW *win;
3309	int x, y, w, h, i;
3310	char temp[80];
3311
3312	ptrs = (PANEL_DATA *)calloc(n, sizeof(PANEL_DATA));
3313
3314	for(i = 0;i < n; ++i)
3315	{ win = panel_window(panels[i]);
3316	getbegyx(win, y, x);
3317	getmaxyx(win, h, w);
3318	ptrs[i].x = x;
3319	ptrs[i].y = y;
3320	ptrs[i].w = w;
3321	ptrs[i].h = h;
3322	sprintf(temp, "Window Number %d", i + 1);
3323	strcpy(ptrs[i].label, temp);
3324	ptrs[i].label_color = i + 1;
3325	if(i + 1 == n)
3326	ptrs[i].next = panels[0];
3327	else
3328	ptrs[i].next = panels[i + 1];
3329	set_panel_userptr(panels[i], &ptrs[i]);
3330	}
3331	}
3332
3333	/* Show the window with a border and a label */
3334	void win_show(WINDOW win, char label, int label_color)
3335	{ int startx, starty, height, width;
3336
3337	getbegyx(win, starty, startx);
3338	getmaxyx(win, height, width);
3339
3340	box(win, 0, 0);
3341	mvwaddch(win, 2, 0, ACS_LTEE);
3342	mvwhline(win, 2, 1, ACS_HLINE, width - 2);
3343	mvwaddch(win, 2, width - 1, ACS_RTEE);
3344
3345	print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color));
3346	}
3347
3348	void print_in_middle(WINDOW win, int starty, int startx, int width, char string, chtype color)
3349	{ int length, x, y;
3350	float temp;
3351
3352	if(win == NULL)
3353	win = stdscr;
3354	getyx(win, y, x);
3355	if(startx != 0)
3356	x = startx;
3357	if(starty != 0)
3358	y = starty;
3359	if(width == 0)
3360	width = 80;
3361
3362	length = strlen(string);
3363	temp = (width - length)/ 2;
3364	x = startx + (int)temp;
3365	wattron(win, color);
3366	mvwprintw(win, y, x, "%s", string);
3367	wattroff(win, color);
3368	refresh();
3369	}</span></font>
3370	</pre></td>
3371	</tr>
3372	</table>
3373	</div>
3374	<p>Concentrate on the main while loop. Once it finds out the type
3375	of key pressed, it takes appropriate action. If 'r' is pressed
3376	resizing mode is started. After this the new sizes are updated as
3377	the user presses the arrow keys. When the user presses
3378	<ENTER> present selection ends and panel is resized by using
3379	the concept explained. While in resizing mode the program doesn't
3380	show how the window is getting resized. It's left as an exercise to
3381	the reader to print a dotted border while it gets resized to a new
3382	position.</p>
3383	<p>When the user presses 'm' the move mode starts. This is a bit
3384	simpler than resizing. As the arrow keys are pressed the new
3385	position is updated and pressing of <ENTER> causes the panel
3386	to be moved by calling the function move_panel().</p>
3387	<p>In this program the user data which is represented as
3388	PANEL_DATA, plays very important role in finding the associated
3389	information with a panel. As written in the comments, the
3390	PANEL_DATA stores the panel sizes, label, label color and a pointer
3391	to the next panel in the cycle.</p>
3392	</div>
3393	<div class="SECT2">
3394	<hr>
3395	<h3 class="SECT2"><a name="PANELSHOWHIDE" id="PANELSHOWHIDE">16.6.
3396	Hiding and Showing Panels</a></h3>
3397	<p>A Panel can be hidden by using the function hide_panel(). This
3398	function merely removes it form the stack of panels, thus hiding it
3399	on the screen once you do update_panels() and doupdate(). It
3400	doesn't destroy the PANEL structure associated with the hidden
3401	panel. It can be shown again by using the show_panel()
3402	function.</p>
3403	<p>The following program shows the hiding of panels. Press 'a' or
3404	'b' or 'c' to show or hide first, second and third windows
3405	respectively. It uses a user data with a small variable hide, which
3406	keeps track of whether the window is hidden or not. For some reason
3407	the function <var class="LITERAL">panel_hidden()</var> which tells
3408	whether a panel is hidden or not is not working. A bug report was
3409	also presented by Michael Andres <a href=
3410	"http://www.geocrawler.com/archives/3/344/1999/9/0/2643549/"
3411	target="_top">here</a></p>
3412	<div class="EXAMPLE"><a name="PPAHI" id="PPAHI"></a>
3413	<p><b>Example 17. Panel Hiding and Showing example</b></p>
3414	<table border="0" bgcolor="#E0E0E0" width="100%">
3415	<tr>
3416	<td>
3417	<pre class="PROGRAMLISTING">
3418	<font color="#000000"><span class=
3419	"INLINEMEDIAOBJECT">#include <panel.h>
3420
3421	typedef struct _PANEL_DATA {
3422	int hide; /* TRUE if panel is hidden */
3423	}PANEL_DATA;
3424
3425	#define NLINES 10
3426	#define NCOLS 40
3427
3428	void init_wins(WINDOW **wins, int n);
3429	void win_show(WINDOW win, char label, int label_color);
3430	void print_in_middle(WINDOW win, int starty, int startx, int width, char string, chtype color);
3431
3432	int main()
3433	{ WINDOW *my_wins[3];
3434	PANEL *my_panels[3];
3435	PANEL_DATA panel_datas[3];
3436	PANEL_DATA *temp;
3437	int ch;
3438
3439	/* Initialize curses */
3440	initscr();
3441	start_color();
3442	cbreak();
3443	noecho();
3444	keypad(stdscr, TRUE);
3445
3446	/* Initialize all the colors */
3447	init_pair(1, COLOR_RED, COLOR_BLACK);
3448	init_pair(2, COLOR_GREEN, COLOR_BLACK);
3449	init_pair(3, COLOR_BLUE, COLOR_BLACK);
3450	init_pair(4, COLOR_CYAN, COLOR_BLACK);
3451
3452	init_wins(my_wins, 3);
3453
3454	/* Attach a panel to each window / / Order is bottom up */
3455	my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
3456	my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
3457	my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
3458
3459	/* Initialize panel datas saying that nothing is hidden */
3460	panel_datas[0].hide = FALSE;
3461	panel_datas[1].hide = FALSE;
3462	panel_datas[2].hide = FALSE;
3463
3464	set_panel_userptr(my_panels[0], &panel_datas[0]);
3465	set_panel_userptr(my_panels[1], &panel_datas[1]);
3466	set_panel_userptr(my_panels[2], &panel_datas[2]);
3467
3468	/* Update the stacking order. 2nd panel will be on top */
3469	update_panels();
3470
3471	/* Show it on the screen */
3472	attron(COLOR_PAIR(4));
3473	mvprintw(LINES - 3, 0, "Show or Hide a window with 'a'(first window) 'b'(Second Window) 'c'(Third Window)");
3474	mvprintw(LINES - 2, 0, "F1 to Exit");
3475
3476	attroff(COLOR_PAIR(4));
3477	doupdate();
3478
3479	while((ch = getch()) != KEY_F(1))
3480	{ switch(ch)
3481	{ case 'a':
3482	temp = (PANEL_DATA *)panel_userptr(my_panels[0]);
3483	if(temp->hide == FALSE)
3484	{ hide_panel(my_panels[0]);
3485	temp->hide = TRUE;
3486	}
3487	else
3488	{ show_panel(my_panels[0]);
3489	temp->hide = FALSE;
3490	}
3491	break;
3492	case 'b':
3493	temp = (PANEL_DATA *)panel_userptr(my_panels[1]);
3494	if(temp->hide == FALSE)
3495	{ hide_panel(my_panels[1]);
3496	temp->hide = TRUE;
3497	}
3498	else
3499	{ show_panel(my_panels[1]);
3500	temp->hide = FALSE;
3501	}
3502	break;
3503	case 'c':
3504	temp = (PANEL_DATA *)panel_userptr(my_panels[2]);
3505	if(temp->hide == FALSE)
3506	{ hide_panel(my_panels[2]);
3507	temp->hide = TRUE;
3508	}
3509	else
3510	{ show_panel(my_panels[2]);
3511	temp->hide = FALSE;
3512	}
3513	break;
3514	}
3515	update_panels();
3516	doupdate();
3517	}
3518	endwin();
3519	return 0;
3520	}
3521
3522	/* Put all the windows */
3523	void init_wins(WINDOW **wins, int n)
3524	{ int x, y, i;
3525	char label[80];
3526
3527	y = 2;
3528	x = 10;
3529	for(i = 0; i < n; ++i)
3530	{ wins[i] = newwin(NLINES, NCOLS, y, x);
3531	sprintf(label, "Window Number %d", i + 1);
3532	win_show(wins[i], label, i + 1);
3533	y += 3;
3534	x += 7;
3535	}
3536	}
3537
3538	/* Show the window with a border and a label */
3539	void win_show(WINDOW win, char label, int label_color)
3540	{ int startx, starty, height, width;
3541
3542	getbegyx(win, starty, startx);
3543	getmaxyx(win, height, width);
3544
3545	box(win, 0, 0);
3546	mvwaddch(win, 2, 0, ACS_LTEE);
3547	mvwhline(win, 2, 1, ACS_HLINE, width - 2);
3548	mvwaddch(win, 2, width - 1, ACS_RTEE);
3549
3550	print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color));
3551	}
3552
3553	void print_in_middle(WINDOW win, int starty, int startx, int width, char string, chtype color)
3554	{ int length, x, y;
3555	float temp;
3556
3557	if(win == NULL)
3558	win = stdscr;
3559	getyx(win, y, x);
3560	if(startx != 0)
3561	x = startx;
3562	if(starty != 0)
3563	y = starty;
3564	if(width == 0)
3565	width = 80;
3566
3567	length = strlen(string);
3568	temp = (width - length)/ 2;
3569	x = startx + (int)temp;
3570	wattron(win, color);
3571	mvwprintw(win, y, x, "%s", string);
3572	wattroff(win, color);
3573	refresh();
3574	}</span></font>
3575	</pre></td>
3576	</tr>
3577	</table>
3578	</div>
3579	</div>
3580	<div class="SECT2">
3581	<hr>
3582	<h3 class="SECT2"><a name="PANELABOVE" id="PANELABOVE">16.7.
3583	panel_above() and panel_below() Functions</a></h3>
3584	<p>The functions <var class="LITERAL">panel_above()</var> and
3585	<var class="LITERAL">panel_below()</var> can be used to find out
3586	the panel above and below a panel. If the argument to these
3587	functions is NULL, then they return a pointer to bottom panel and
3588	top panel respectively.</p>
3589	</div>
3590	</div>
3591	<div class="SECT1">
3592	<hr>
3593	<h2 class="SECT1"><a name="MENUS" id="MENUS">17. Menus
3594	Library</a></h2>
3595	<p>The menus library provides a nice extension to basic curses,
3596	through which you can create menus. It provides a set of functions
3597	to create menus. But they have to be customized to give a nicer
3598	look, with colors etc. Let's get into the details.</p>
3599	<p>A menu is a screen display that assists the user to choose some
3600	subset of a given set of items. To put it simple, a menu is a
3601	collection of items from which one or more items can be chosen.
3602	Some readers might not be aware of multiple item selection
3603	capability. Menu library provides functionality to write menus from
3604	which the user can chose more than one item as the preferred
3605	choice. This is dealt with in a later section. Now it is time for
3606	some rudiments.</p>
3607	<div class="SECT2">
3608	<hr>
3609	<h3 class="SECT2"><a name="MENUBASICS" id="MENUBASICS">17.1. The
3610	Basics</a></h3>
3611	<p>To create menus, you first create items, and then post the menu
3612	to the display. After that, all the processing of user responses is
3613	done in an elegant function menu_driver() which is the work horse
3614	of any menu program.</p>
3615	<p>The general flow of control of a menu program looks like
3616	this.</p>
3617	<ol type="1">
3618	<li>
3619	<p>Initialize curses</p>
3620	</li>
3621	<li>
3622	<p>Create items using new_item(). You can specify a name and
3623	description for the items.</p>
3624	</li>
3625	<li>
3626	<p>Create the menu with new_menu() by specifying the items to be
3627	attached with.</p>
3628	</li>
3629	<li>
3630	<p>Post the menu with menu_post() and refresh the screen.</p>
3631	</li>
3632	<li>
3633	<p>Process the user requests with a loop and do necessary updates
3634	to menu with menu_driver.</p>
3635	</li>
3636	<li>
3637	<p>Unpost the menu with menu_unpost()</p>
3638	</li>
3639	<li>
3640	<p>Free the memory allocated to menu by free_menu()</p>
3641	</li>
3642	<li>
3643	<p>Free the memory allocated to the items with free_item()</p>
3644	</li>
3645	<li>
3646	<p>End curses</p>
3647	</li>
3648	</ol>
3649	<p>Let's see a program which prints a simple menu and updates the
3650	current selection with up, down arrows.</p>
3651	</div>
3652	<div class="SECT2">
3653	<hr>
3654	<h3 class="SECT2"><a name="COMPILEMENUS" id="COMPILEMENUS">17.2.
3655	Compiling With the Menu Library</a></h3>
3656	<p>To use menu library functions, you have to include menu.h and to
3657	link the program with menu library the flag -lmenu should be added
3658	along with -lncurses in that order.</p>
3659	<table border="0" bgcolor="#E0E0E0" width="100%">
3660	<tr>
3661	<td>
3662	<pre class="PROGRAMLISTING">
3663	<font color="#000000"> #include <menu.h>
3664	.
3665	.
3666	.
3667
3668	compile and link: gcc <program file> -lmenu -lncurses</font>
3669	</pre></td>
3670	</tr>
3671	</table>
3672	<div class="EXAMPLE"><a name="MMESI" id="MMESI"></a>
3673	<p><b>Example 18. Menu Basics</b></p>
3674	<table border="0" bgcolor="#E0E0E0" width="100%">
3675	<tr>
3676	<td>
3677	<pre class="PROGRAMLISTING">
3678	<font color="#000000"><span class=
3679	"INLINEMEDIAOBJECT">#include <curses.h>
3680	#include <menu.h>
3681
3682	#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
3683	#define CTRLD 4
3684
3685	char *choices[] = {
3686	"Choice 1",
3687	"Choice 2",
3688	"Choice 3",
3689	"Choice 4",
3690	"Exit",
3691	};
3692
3693	int main()
3694	{ ITEM **my_items;
3695	int c;
3696	MENU *my_menu;
3697	int n_choices, i;
3698	ITEM *cur_item;
3699
3700
3701	initscr();
3702	cbreak();
3703	noecho();
3704	keypad(stdscr, TRUE);
3705
3706	n_choices = ARRAY_SIZE(choices);
3707	my_items = (ITEM *)calloc(n_choices + 1, sizeof(ITEM ));
3708
3709	for(i = 0; i < n_choices; ++i)
3710	my_items[i] = new_item(choices[i], choices[i]);
3711	my_items[n_choices] = (ITEM *)NULL;
3712
3713	my_menu = new_menu((ITEM **)my_items);
3714	mvprintw(LINES - 2, 0, "F1 to Exit");
3715	post_menu(my_menu);
3716	refresh();
3717
3718	while((c = getch()) != KEY_F(1))
3719	{ switch(c)
3720	{ case KEY_DOWN:
3721	menu_driver(my_menu, REQ_DOWN_ITEM);
3722	break;
3723	case KEY_UP:
3724	menu_driver(my_menu, REQ_UP_ITEM);
3725	break;
3726	}
3727	}
3728
3729	free_item(my_items[0]);
3730	free_item(my_items[1]);
3731	free_menu(my_menu);
3732	endwin();
3733	}
3734	</span></font>
3735	</pre></td>
3736	</tr>
3737	</table>
3738	</div>
3739	<p>This program demonstrates the basic concepts involved in
3740	creating a menu using menus library. First we create the items
3741	using new_item() and then attach them to the menu with new_menu()
3742	function. After posting the menu and refreshing the screen, the
3743	main processing loop starts. It reads user input and takes
3744	corresponding action. The function menu_driver() is the main work
3745	horse of the menu system. The second parameter to this function
3746	tells what's to be done with the menu. According to the parameter,
3747	menu_driver() does the corresponding task. The value can be either
3748	a menu navigational request, an ascii character, or a KEY_MOUSE
3749	special key associated with a mouse event.</p>
3750	<p>The menu_driver accepts following navigational requests.</p>
3751	<table border="0" bgcolor="#E0E0E0" width="100%">
3752	<tr>
3753	<td>
3754	<pre class="PROGRAMLISTING">
3755	<font color=
3756	"#000000"> REQ_LEFT_ITEM Move left to an item.
3757	REQ_RIGHT_ITEM Move right to an item.
3758	REQ_UP_ITEM Move up to an item.
3759	REQ_DOWN_ITEM Move down to an item.
3760	REQ_SCR_ULINE Scroll up a line.
3761	REQ_SCR_DLINE Scroll down a line.
3762	REQ_SCR_DPAGE Scroll down a page.
3763	REQ_SCR_UPAGE Scroll up a page.
3764	REQ_FIRST_ITEM Move to the first item.
3765	REQ_LAST_ITEM Move to the last item.
3766	REQ_NEXT_ITEM Move to the next item.
3767	REQ_PREV_ITEM Move to the previous item.
3768	REQ_TOGGLE_ITEM Select/deselect an item.
3769	REQ_CLEAR_PATTERN Clear the menu pattern buffer.
3770	REQ_BACK_PATTERN Delete the previous character from the pattern buffer.
3771	REQ_NEXT_MATCH Move to the next item matching the pattern match.
3772	REQ_PREV_MATCH Move to the previous item matching the pattern match. </font>
3773	</pre></td>
3774	</tr>
3775	</table>
3776	<p>Don't get overwhelmed by the number of options. We will see them
3777	slowly one after another. The options of interest in this example
3778	are REQ_UP_ITEM and REQ_DOWN_ITEM. These two options when passed to
3779	menu_driver, menu driver updates the current item to one item up or
3780	down respectively.</p>
3781	</div>
3782	<div class="SECT2">
3783	<hr>
3784	<h3 class="SECT2"><a name="MENUDRIVER" id="MENUDRIVER">17.3. Menu
3785	Driver: The work horse of the menu system</a></h3>
3786	<p>As you have seen in the above example, menu_driver plays an
3787	important role in updating the menu. It is very important to
3788	understand various options it takes and what they do. As explained
3789	above, the second parameter to menu_driver() can be either a
3790	navigational request, a printable character or a KEY_MOUSE key.
3791	Let's dissect the different navigational requests.</p>
3792	<ul>
3793	<li>
3794	<p><em>REQ_LEFT_ITEM and REQ_RIGHT_ITEM</em></p>
3795	<p>A Menu can be displayed with multiple columns for more than one
3796	item. This can be done by using the <var class=
3797	"LITERAL">menu_format()</var>function. When a multi columnar menu
3798	is displayed these requests cause the menu driver to move the
3799	current selection to left or right.</p>
3800	</li>
3801	<li>
3802	<p><em>REQ_UP_ITEM and REQ_DOWN_ITEM</em></p>
3803	<p>These two options you have seen in the above example. These
3804	options when given, makes the menu_driver to move the current
3805	selection to an item up or down.</p>
3806	</li>
3807	<li>
3808	<p><em>REQ_SCR_* options</em></p>
3809	<p>The four options REQ_SCR_ULINE, REQ_SCR_DLINE, REQ_SCR_DPAGE,
3810	REQ_SCR_UPAGE are related to scrolling. If all the items in the
3811	menu cannot be displayed in the menu sub window, then the menu is
3812	scrollable. These requests can be given to the menu_driver to do
3813	the scrolling either one line up, down or one page down or up
3814	respectively.</p>
3815	</li>
3816	<li>
3817	<p><em>REQ_FIRST_ITEM, REQ_LAST_ITEM, REQ_NEXT_ITEM and
3818	REQ_PREV_ITEM</em></p>
3819	<p>These requests are self explanatory.</p>
3820	</li>
3821	<li>
3822	<p><em>REQ_TOGGLE_ITEM</em></p>
3823	<p>This request when given, toggles the present selection. This
3824	option is to be used only in a multi valued menu. So to use this
3825	request the option O_ONEVALUE must be off. This option can be made
3826	off or on with set_menu_opts().</p>
3827	</li>
3828	<li>
3829	<p><em>Pattern Requests</em></p>
3830	<p>Every menu has an associated pattern buffer, which is used to
3831	find the nearest match to the ascii characters entered by the user.
3832	Whenever ascii characters are given to menu_driver, it puts in to
3833	the pattern buffer. It also tries to find the nearest match to the
3834	pattern in the items list and moves current selection to that item.
3835	The request REQ_CLEAR_PATTERN clears the pattern buffer. The
3836	request REQ_BACK_PATTERN deletes the previous character in the
3837	pattern buffer. In case the pattern matches more than one item then
3838	the matched items can be cycled through REQ_NEXT_MATCH and
3839	REQ_PREV_MATCH which move the current selection to the next and
3840	previous matches respectively.</p>
3841	</li>
3842	<li>
3843	<p><em>Mouse Requests</em></p>
3844	<p>In case of KEY_MOUSE requests, according to the mouse position
3845	an action is taken accordingly. The action to be taken is explained
3846	in the man page as,</p>
3847	<table border="0" bgcolor="#E0E0E0" width="90%">
3848	<tr>
3849	<td>
3850	<pre class="PROGRAMLISTING">
3851	<font color=
3852	"#000000"><em> If the second argument is the KEY_MOUSE special key, the
3853	associated mouse event is translated into one of the above
3854	pre-defined requests. Currently only clicks in the user
3855	window (e.g. inside the menu display area or the decora
3856	tion window) are handled. If you click above the display
3857	region of the menu, a REQ_SCR_ULINE is generated, if you
3858	doubleclick a REQ_SCR_UPAGE is generated and if you
3859	tripleclick a REQ_FIRST_ITEM is generated. If you click
3860	below the display region of the menu, a REQ_SCR_DLINE is
3861	generated, if you doubleclick a REQ_SCR_DPAGE is generated
3862	and if you tripleclick a REQ_LAST_ITEM is generated. If
3863	you click at an item inside the display area of the menu,
3864	the menu cursor is positioned to that item.</em></font>
3865	</pre></td>
3866	</tr>
3867	</table>
3868	</li>
3869	</ul>
3870	<p>Each of the above requests will be explained in the following
3871	lines with several examples whenever appropriate.</p>
3872	</div>
3873	<div class="SECT2">
3874	<hr>
3875	<h3 class="SECT2"><a name="MENUWINDOWS" id="MENUWINDOWS">17.4. Menu
3876	Windows</a></h3>
3877	<p>Every menu created is associated with a window and a sub window.
3878	The menu window displays any title or border associated with the
3879	menu. The menu sub window displays the menu items currently
3880	available for selection. But we didn't specify any window or sub
3881	window in the simple example. When a window is not specified,
3882	stdscr is taken as the main window, and then menu system calculates
3883	the sub window size required for the display of items. Then items
3884	are displayed in the calculated sub window. So let's play with
3885	these windows and display a menu with a border and a title.</p>
3886	<div class="EXAMPLE"><a name="MMEWI" id="MMEWI"></a>
3887	<p><b>Example 19. Menu Windows Usage example</b></p>
3888	<table border="0" bgcolor="#E0E0E0" width="100%">
3889	<tr>
3890	<td>
3891	<pre class="PROGRAMLISTING">
3892	<font color="#000000"><span class=
3893	"INLINEMEDIAOBJECT">#include <menu.h>
3894
3895	#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
3896	#define CTRLD 4
3897
3898	char *choices[] = {
3899	"Choice 1",
3900	"Choice 2",
3901	"Choice 3",
3902	"Choice 4",
3903	"Exit",
3904	(char *)NULL,
3905	};
3906	void print_in_middle(WINDOW win, int starty, int startx, int width, char string, chtype color);
3907
3908	int main()
3909	{ ITEM **my_items;
3910	int c;
3911	MENU *my_menu;
3912	WINDOW *my_menu_win;
3913	int n_choices, i;
3914
3915	/* Initialize curses */
3916	initscr();
3917	start_color();
3918	cbreak();
3919	noecho();
3920	keypad(stdscr, TRUE);
3921	init_pair(1, COLOR_RED, COLOR_BLACK);
3922
3923	/* Create items */
3924	n_choices = ARRAY_SIZE(choices);
3925	my_items = (ITEM *)calloc(n_choices, sizeof(ITEM ));
3926	for(i = 0; i < n_choices; ++i)
3927	my_items[i] = new_item(choices[i], choices[i]);
3928
3929	/* Crate menu */
3930	my_menu = new_menu((ITEM **)my_items);
3931
3932	/* Create the window to be associated with the menu */
3933	my_menu_win = newwin(10, 40, 4, 4);
3934	keypad(my_menu_win, TRUE);
3935
3936	/* Set main window and sub window */
3937	set_menu_win(my_menu, my_menu_win);
3938	set_menu_sub(my_menu, derwin(my_menu_win, 6, 38, 3, 1));
3939
3940	/* Set menu mark to the string " * " */
3941	set_menu_mark(my_menu, " * ");
3942
3943	/* Print a border around the main window and print a title */
3944	box(my_menu_win, 0, 0);
3945	print_in_middle(my_menu_win, 1, 0, 40, "My Menu", COLOR_PAIR(1));
3946	mvwaddch(my_menu_win, 2, 0, ACS_LTEE);
3947	mvwhline(my_menu_win, 2, 1, ACS_HLINE, 38);
3948	mvwaddch(my_menu_win, 2, 39, ACS_RTEE);
3949	mvprintw(LINES - 2, 0, "F1 to exit");
3950	refresh();
3951
3952	/* Post the menu */
3953	post_menu(my_menu);
3954	wrefresh(my_menu_win);
3955
3956	while((c = wgetch(my_menu_win)) != KEY_F(1))
3957	{ switch(c)
3958	{ case KEY_DOWN:
3959	menu_driver(my_menu, REQ_DOWN_ITEM);
3960	break;
3961	case KEY_UP:
3962	menu_driver(my_menu, REQ_UP_ITEM);
3963	break;
3964	}
3965	wrefresh(my_menu_win);
3966	}
3967
3968	/* Unpost and free all the memory taken up */
3969	unpost_menu(my_menu);
3970	free_menu(my_menu);
3971	for(i = 0; i < n_choices; ++i)
3972	free_item(my_items[i]);
3973	endwin();
3974	}
3975
3976	void print_in_middle(WINDOW win, int starty, int startx, int width, char string, chtype color)
3977	{ int length, x, y;
3978	float temp;
3979
3980	if(win == NULL)
3981	win = stdscr;
3982	getyx(win, y, x);
3983	if(startx != 0)
3984	x = startx;
3985	if(starty != 0)
3986	y = starty;
3987	if(width == 0)
3988	width = 80;
3989
3990	length = strlen(string);
3991	temp = (width - length)/ 2;
3992	x = startx + (int)temp;
3993	wattron(win, color);
3994	mvwprintw(win, y, x, "%s", string);
3995	wattroff(win, color);
3996	refresh();
3997	}</span></font>
3998	</pre></td>
3999	</tr>
4000	</table>
4001	</div>
4002	<p>This example creates a menu with a title, border, a fancy line
4003	separating title and the items. As you can see, in order to attach
4004	a window to a menu the function set_menu_win() has to be used. Then
4005	we attach the sub window also. This displays the items in the sub
4006	window. You can also set the mark string which gets displayed to
4007	the left of the selected item with set_menu_mark().</p>
4008	</div>
4009	<div class="SECT2">
4010	<hr>
4011	<h3 class="SECT2"><a name="SCROLLMENUS" id="SCROLLMENUS">17.5.
4012	Scrolling Menus</a></h3>
4013	<p>If the sub window given for a window is not big enough to show
4014	all the items, then the menu will be scrollable. When you are on
4015	the last item in the present list, if you send REQ_DOWN_ITEM, it
4016	gets translated into REQ_SCR_DLINE and the menu scrolls by one
4017	item. You can manually give REQ_SCR_ operations to do scrolling.
4018	Let's see how it can be done.</p>
4019	<div class="EXAMPLE"><a name="MMESC" id="MMESC"></a>
4020	<p><b>Example 20. Scrolling Menus example</b></p>
4021	<table border="0" bgcolor="#E0E0E0" width="100%">
4022	<tr>
4023	<td>
4024	<pre class="PROGRAMLISTING">
4025	<font color="#000000"><span class=
4026	"INLINEMEDIAOBJECT">#include <curses.h>
4027	#include <menu.h>
4028
4029	#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4030	#define CTRLD 4
4031
4032	char *choices[] = {
4033	"Choice 1",
4034	"Choice 2",
4035	"Choice 3",
4036	"Choice 4",
4037	"Choice 5",
4038	"Choice 6",
4039	"Choice 7",
4040	"Choice 8",
4041	"Choice 9",
4042	"Choice 10",
4043	"Exit",
4044	(char *)NULL,
4045	};
4046	void print_in_middle(WINDOW win, int starty, int startx, int width, char string, chtype color);
4047
4048	int main()
4049	{ ITEM **my_items;
4050	int c;
4051	MENU *my_menu;
4052	WINDOW *my_menu_win;
4053	int n_choices, i;
4054
4055	/* Initialize curses */
4056	initscr();
4057	start_color();
4058	cbreak();
4059	noecho();
4060	keypad(stdscr, TRUE);
4061	init_pair(1, COLOR_RED, COLOR_BLACK);
4062	init_pair(2, COLOR_CYAN, COLOR_BLACK);
4063
4064	/* Create items */
4065	n_choices = ARRAY_SIZE(choices);
4066	my_items = (ITEM *)calloc(n_choices, sizeof(ITEM ));
4067	for(i = 0; i < n_choices; ++i)
4068	my_items[i] = new_item(choices[i], choices[i]);
4069
4070	/* Crate menu */
4071	my_menu = new_menu((ITEM **)my_items);
4072
4073	/* Create the window to be associated with the menu */
4074	my_menu_win = newwin(10, 40, 4, 4);
4075	keypad(my_menu_win, TRUE);
4076
4077	/* Set main window and sub window */
4078	set_menu_win(my_menu, my_menu_win);
4079	set_menu_sub(my_menu, derwin(my_menu_win, 6, 38, 3, 1));
4080	set_menu_format(my_menu, 5, 1);
4081
4082	/* Set menu mark to the string " * " */
4083	set_menu_mark(my_menu, " * ");
4084
4085	/* Print a border around the main window and print a title */
4086	box(my_menu_win, 0, 0);
4087	print_in_middle(my_menu_win, 1, 0, 40, "My Menu", COLOR_PAIR(1));
4088	mvwaddch(my_menu_win, 2, 0, ACS_LTEE);
4089	mvwhline(my_menu_win, 2, 1, ACS_HLINE, 38);
4090	mvwaddch(my_menu_win, 2, 39, ACS_RTEE);
4091
4092	/* Post the menu */
4093	post_menu(my_menu);
4094	wrefresh(my_menu_win);
4095
4096	attron(COLOR_PAIR(2));
4097	mvprintw(LINES - 2, 0, "Use PageUp and PageDown to scoll down or up a page of items");
4098	mvprintw(LINES - 1, 0, "Arrow Keys to navigate (F1 to Exit)");
4099	attroff(COLOR_PAIR(2));
4100	refresh();
4101
4102	while((c = wgetch(my_menu_win)) != KEY_F(1))
4103	{ switch(c)
4104	{ case KEY_DOWN:
4105	menu_driver(my_menu, REQ_DOWN_ITEM);
4106	break;
4107	case KEY_UP:
4108	menu_driver(my_menu, REQ_UP_ITEM);
4109	break;
4110	case KEY_NPAGE:
4111	menu_driver(my_menu, REQ_SCR_DPAGE);
4112	break;
4113	case KEY_PPAGE:
4114	menu_driver(my_menu, REQ_SCR_UPAGE);
4115	break;
4116	}
4117	wrefresh(my_menu_win);
4118	}
4119
4120	/* Unpost and free all the memory taken up */
4121	unpost_menu(my_menu);
4122	free_menu(my_menu);
4123	for(i = 0; i < n_choices; ++i)
4124	free_item(my_items[i]);
4125	endwin();
4126	}
4127
4128	void print_in_middle(WINDOW win, int starty, int startx, int width, char string, chtype color)
4129	{ int length, x, y;
4130	float temp;
4131
4132	if(win == NULL)
4133	win = stdscr;
4134	getyx(win, y, x);
4135	if(startx != 0)
4136	x = startx;
4137	if(starty != 0)
4138	y = starty;
4139	if(width == 0)
4140	width = 80;
4141
4142	length = strlen(string);
4143	temp = (width - length)/ 2;
4144	x = startx + (int)temp;
4145	wattron(win, color);
4146	mvwprintw(win, y, x, "%s", string);
4147	wattroff(win, color);
4148	refresh();
4149	}</span></font>
4150	</pre></td>
4151	</tr>
4152	</table>
4153	</div>
4154	<p>This program is self-explanatory. In this example the number of
4155	choices has been increased to ten, which is larger than our sub
4156	window size which can hold 6 items. This message has to be
4157	explicitly conveyed to the menu system with the function
4158	set_menu_format(). In here we specify the number of rows and
4159	columns we want to be displayed for a single page. We can specify
4160	any number of items to be shown, in the rows variables, if it is
4161	less than the height of the sub window. If the key pressed by the
4162	user is a PAGE UP or PAGE DOWN, the menu is scrolled a page due to
4163	the requests (REQ_SCR_DPAGE and REQ_SCR_UPAGE) given to
4164	menu_driver().</p>
4165	</div>
4166	<div class="SECT2">
4167	<hr>
4168	<h3 class="SECT2"><a name="MULTICOLUMN" id="MULTICOLUMN">17.6.
4169	Multi Columnar Menus</a></h3>
4170	<p>In the above example you have seen how to use the function
4171	set_menu_format(). I didn't mention what the cols variable (third
4172	parameter) does. Well, If your sub window is wide enough, you can
4173	opt to display more than one item per row. This can be specified in
4174	the cols variable. To make things simpler, the following example
4175	doesn't show descriptions for the items.</p>
4176	<div class="EXAMPLE"><a name="MMEMUCO" id="MMEMUCO"></a>
4177	<p><b>Example 21. Milt Columnar Menus Example</b></p>
4178	<table border="0" bgcolor="#E0E0E0" width="100%">
4179	<tr>
4180	<td>
4181	<pre class="PROGRAMLISTING">
4182	<font color="#000000"><span class=
4183	"INLINEMEDIAOBJECT">#include <curses.h>
4184	#include <menu.h>
4185
4186	#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4187	#define CTRLD 4
4188
4189	char *choices[] = {
4190	"Choice 1", "Choice 2", "Choice 3", "Choice 4", "Choice 5",
4191	"Choice 6", "Choice 7", "Choice 8", "Choice 9", "Choice 10",
4192	"Choice 11", "Choice 12", "Choice 13", "Choice 14", "Choice 15",
4193	"Choice 16", "Choice 17", "Choice 18", "Choice 19", "Choice 20",
4194	"Exit",
4195	(char *)NULL,
4196	};
4197
4198	int main()
4199	{ ITEM **my_items;
4200	int c;
4201	MENU *my_menu;
4202	WINDOW *my_menu_win;
4203	int n_choices, i;
4204
4205	/* Initialize curses */
4206	initscr();
4207	start_color();
4208	cbreak();
4209	noecho();
4210	keypad(stdscr, TRUE);
4211	init_pair(1, COLOR_RED, COLOR_BLACK);
4212	init_pair(2, COLOR_CYAN, COLOR_BLACK);
4213
4214	/* Create items */
4215	n_choices = ARRAY_SIZE(choices);
4216	my_items = (ITEM *)calloc(n_choices, sizeof(ITEM ));
4217	for(i = 0; i < n_choices; ++i)
4218	my_items[i] = new_item(choices[i], choices[i]);
4219
4220	/* Crate menu */
4221	my_menu = new_menu((ITEM **)my_items);
4222
4223	/* Set menu option not to show the description */
4224	menu_opts_off(my_menu, O_SHOWDESC);
4225
4226	/* Create the window to be associated with the menu */
4227	my_menu_win = newwin(10, 70, 4, 4);
4228	keypad(my_menu_win, TRUE);
4229
4230	/* Set main window and sub window */
4231	set_menu_win(my_menu, my_menu_win);
4232	set_menu_sub(my_menu, derwin(my_menu_win, 6, 68, 3, 1));
4233	set_menu_format(my_menu, 5, 3);
4234	set_menu_mark(my_menu, " * ");
4235
4236	/* Print a border around the main window and print a title */
4237	box(my_menu_win, 0, 0);
4238
4239	attron(COLOR_PAIR(2));
4240	mvprintw(LINES - 3, 0, "Use PageUp and PageDown to scroll");
4241	mvprintw(LINES - 2, 0, "Use Arrow Keys to navigate (F1 to Exit)");
4242	attroff(COLOR_PAIR(2));
4243	refresh();
4244
4245	/* Post the menu */
4246	post_menu(my_menu);
4247	wrefresh(my_menu_win);
4248
4249	while((c = wgetch(my_menu_win)) != KEY_F(1))
4250	{ switch(c)
4251	{ case KEY_DOWN:
4252	menu_driver(my_menu, REQ_DOWN_ITEM);
4253	break;
4254	case KEY_UP:
4255	menu_driver(my_menu, REQ_UP_ITEM);
4256	break;
4257	case KEY_LEFT:
4258	menu_driver(my_menu, REQ_LEFT_ITEM);
4259	break;
4260	case KEY_RIGHT:
4261	menu_driver(my_menu, REQ_RIGHT_ITEM);
4262	break;
4263	case KEY_NPAGE:
4264	menu_driver(my_menu, REQ_SCR_DPAGE);
4265	break;
4266	case KEY_PPAGE:
4267	menu_driver(my_menu, REQ_SCR_UPAGE);
4268	break;
4269	}
4270	wrefresh(my_menu_win);
4271	}
4272
4273	/* Unpost and free all the memory taken up */
4274	unpost_menu(my_menu);
4275	free_menu(my_menu);
4276	for(i = 0; i < n_choices; ++i)
4277	free_item(my_items[i]);
4278	endwin();
4279	}</span></font>
4280	</pre></td>
4281	</tr>
4282	</table>
4283	</div>
4284	<p>Watch the function call to set_menu_format(). It specifies the
4285	number of columns to be 3, thus displaying 3 items per row. We have
4286	also switched off the showing descriptions with the function
4287	menu_opts_off(). There are couple of functions set_menu_opts(),
4288	menu_opts_on() and menu_opts() which can be used to manipulate menu
4289	options. The following menu options can be specified.</p>
4290	<table border="0" bgcolor="#E0E0E0" width="100%">
4291	<tr>
4292	<td>
4293	<pre class="PROGRAMLISTING">
4294	<font color="#000000"> O_ONEVALUE
4295	Only one item can be selected for this menu.
4296
4297	O_SHOWDESC
4298	Display the item descriptions when the menu is
4299	posted.
4300
4301	O_ROWMAJOR
4302	Display the menu in row-major order.
4303
4304	O_IGNORECASE
4305	Ignore the case when pattern-matching.
4306
4307	O_SHOWMATCH
4308	Move the cursor to within the item name while pat
4309	tern-matching.
4310
4311	O_NONCYCLIC
4312	Don't wrap around next-item and previous-item,
4313	requests to the other end of the menu.</font>
4314	</pre></td>
4315	</tr>
4316	</table>
4317	<p>All options are on by default. You can switch specific
4318	attributes on or off with menu_opts_on() and menu_opts_off()
4319	functions. You can also use set_menu_opts() to directly specify the
4320	options. The argument to this function should be a OR ed value of
4321	some of those above constants. The function menu_opts() can be used
4322	to find out a menu's present options.</p>
4323	</div>
4324	<div class="SECT2">
4325	<hr>
4326	<h3 class="SECT2"><a name="MULTIVALUEMENUS" id=
4327	"MULTIVALUEMENUS">17.7. Multi Valued Menus</a></h3>
4328	<p>You might be wondering what if you switch off the option
4329	O_ONEVALUE. Then the menu becomes multi-valued. That means you can
4330	select more than one item. This brings us to the request
4331	REQ_TOGGLE_ITEM. Let's see it in action.</p>
4332	<div class="EXAMPLE"><a name="MMETO" id="MMETO"></a>
4333	<p><b>Example 22. Multi Valued Menus example</b></p>
4334	<table border="0" bgcolor="#E0E0E0" width="100%">
4335	<tr>
4336	<td>
4337	<pre class="PROGRAMLISTING">
4338	<font color="#000000"><span class=
4339	"INLINEMEDIAOBJECT">#include <curses.h>
4340	#include <menu.h>
4341
4342	#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4343	#define CTRLD 4
4344
4345	char *choices[] = {
4346	"Choice 1",
4347	"Choice 2",
4348	"Choice 3",
4349	"Choice 4",
4350	"Choice 5",
4351	"Choice 6",
4352	"Choice 7",
4353	"Exit",
4354	};
4355
4356	int main()
4357	{ ITEM **my_items;
4358	int c;
4359	MENU *my_menu;
4360	int n_choices, i;
4361	ITEM *cur_item;
4362
4363	/* Initialize curses */
4364	initscr();
4365	cbreak();
4366	noecho();
4367	keypad(stdscr, TRUE);
4368
4369	/* Initialize items */
4370	n_choices = ARRAY_SIZE(choices);
4371	my_items = (ITEM *)calloc(n_choices + 1, sizeof(ITEM ));
4372	for(i = 0; i < n_choices; ++i)
4373	my_items[i] = new_item(choices[i], choices[i]);
4374	my_items[n_choices] = (ITEM *)NULL;
4375
4376	my_menu = new_menu((ITEM **)my_items);
4377
4378	/* Make the menu multi valued */
4379	menu_opts_off(my_menu, O_ONEVALUE);
4380
4381	mvprintw(LINES - 3, 0, "Use <SPACE> to select or unselect an item.");
4382	mvprintw(LINES - 2, 0, "<ENTER> to see presently selected items(F1 to Exit)");
4383	post_menu(my_menu);
4384	refresh();
4385
4386	while((c = getch()) != KEY_F(1))
4387	{ switch(c)
4388	{ case KEY_DOWN:
4389	menu_driver(my_menu, REQ_DOWN_ITEM);
4390	break;
4391	case KEY_UP:
4392	menu_driver(my_menu, REQ_UP_ITEM);
4393	break;
4394	case ' ':
4395	menu_driver(my_menu, REQ_TOGGLE_ITEM);
4396	break;
4397	case 10: /* Enter */
4398	{ char temp[200];
4399	ITEM **items;
4400
4401	items = menu_items(my_menu);
4402	temp[0] = '\0';
4403	for(i = 0; i < item_count(my_menu); ++i)
4404	if(item_value(items[i]) == TRUE)
4405	{ strcat(temp, item_name(items[i]));
4406	strcat(temp, " ");
4407	}
4408	move(20, 0);
4409	clrtoeol();
4410	mvprintw(20, 0, temp);
4411	refresh();
4412	}
4413	break;
4414	}
4415	}
4416
4417	free_item(my_items[0]);
4418	free_item(my_items[1]);
4419	free_menu(my_menu);
4420	endwin();
4421	}
4422	</span></font>
4423	</pre></td>
4424	</tr>
4425	</table>
4426	</div>
4427	<p>Whew, A lot of new functions. Let's take them one after another.
4428	Firstly, the REQ_TOGGLE_ITEM. In a multi-valued menu, the user
4429	should be allowed to select or un select more than one item. The
4430	request REQ_TOGGLE_ITEM toggles the present selection. In this case
4431	when space is pressed REQ_TOGGLE_ITEM request is sent to
4432	menu_driver to achieve the result.</p>
4433	<p>Now when the user presses <ENTER> we show the items he
4434	presently selected. First we find out the items associated with the
4435	menu using the function menu_items(). Then we loop through the
4436	items to find out if the item is selected or not. The function
4437	item_value() returns TRUE if an item is selected. The function
4438	item_count() returns the number of items in the menu. The item name
4439	can be found with item_name(). You can also find the description
4440	associated with an item using item_description().</p>
4441	</div>
4442	<div class="SECT2">
4443	<hr>
4444	<h3 class="SECT2"><a name="MENUOPT" id="MENUOPT">17.8. Menu
4445	Options</a></h3>
4446	<p>Well, by this time you must be itching for some difference in
4447	your menu, with lots of functionality. I know. You want Colors !!!.
4448	You want to create nice menus similar to those text mode <a href=
4449	"http://www.jersey.net/~debinjoe/games/" target="_top">dos
4450	games</a>. The functions set_menu_fore() and set_menu_back() can be
4451	used to change the attribute of the selected item and unselected
4452	item. The names are misleading. They don't change menu's foreground
4453	or background which would have been useless.</p>
4454	<p>The function set_menu_grey() can be used to set the display
4455	attribute for the non-selectable items in the menu. This brings us
4456	to the interesting option for an item the one and only
4457	O_SELECTABLE. We can turn it off by the function item_opts_off()
4458	and after that that item is not selectable. It's like a grayed item
4459	in those fancy windows menus. Let's put these concepts in practice
4460	with this example</p>
4461	<div class="EXAMPLE"><a name="MMEAT" id="MMEAT"></a>
4462	<p><b>Example 23. Menu Options example</b></p>
4463	<table border="0" bgcolor="#E0E0E0" width="100%">
4464	<tr>
4465	<td>
4466	<pre class="PROGRAMLISTING">
4467	<font color="#000000"><span class=
4468	"INLINEMEDIAOBJECT">#include <menu.h>
4469
4470	#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4471	#define CTRLD 4
4472
4473	char *choices[] = {
4474	"Choice 1",
4475	"Choice 2",
4476	"Choice 3",
4477	"Choice 4",
4478	"Choice 5",
4479	"Choice 6",
4480	"Choice 7",
4481	"Exit",
4482	};
4483
4484	int main()
4485	{ ITEM **my_items;
4486	int c;
4487	MENU *my_menu;
4488	int n_choices, i;
4489	ITEM *cur_item;
4490
4491	/* Initialize curses */
4492	initscr();
4493	start_color();
4494	cbreak();
4495	noecho();
4496	keypad(stdscr, TRUE);
4497	init_pair(1, COLOR_RED, COLOR_BLACK);
4498	init_pair(2, COLOR_GREEN, COLOR_BLACK);
4499	init_pair(3, COLOR_MAGENTA, COLOR_BLACK);
4500
4501	/* Initialize items */
4502	n_choices = ARRAY_SIZE(choices);
4503	my_items = (ITEM *)calloc(n_choices + 1, sizeof(ITEM ));
4504	for(i = 0; i < n_choices; ++i)
4505	my_items[i] = new_item(choices[i], choices[i]);
4506	my_items[n_choices] = (ITEM *)NULL;
4507	item_opts_off(my_items[3], O_SELECTABLE);
4508	item_opts_off(my_items[6], O_SELECTABLE);
4509
4510	/* Create menu */
4511	my_menu = new_menu((ITEM **)my_items);
4512
4513	/* Set fore ground and back ground of the menu */
4514	set_menu_fore(my_menu, COLOR_PAIR(1) \| A_REVERSE);
4515	set_menu_back(my_menu, COLOR_PAIR(2));
4516	set_menu_grey(my_menu, COLOR_PAIR(3));
4517
4518	/* Post the menu */
4519	mvprintw(LINES - 3, 0, "Press <ENTER> to see the option selected");
4520	mvprintw(LINES - 2, 0, "Up and Down arrow keys to naviage (F1 to Exit)");
4521	post_menu(my_menu);
4522	refresh();
4523
4524	while((c = getch()) != KEY_F(1))
4525	{ switch(c)
4526	{ case KEY_DOWN:
4527	menu_driver(my_menu, REQ_DOWN_ITEM);
4528	break;
4529	case KEY_UP:
4530	menu_driver(my_menu, REQ_UP_ITEM);
4531	break;
4532	case 10: /* Enter */
4533	move(20, 0);
4534	clrtoeol();
4535	mvprintw(20, 0, "Item selected is : %s",
4536	item_name(current_item(my_menu)));
4537	pos_menu_cursor(my_menu);
4538	break;
4539	}
4540	}
4541	unpost_menu(my_menu);
4542	for(i = 0; i < n_choices; ++i)
4543	free_item(my_items[i]);
4544	free_menu(my_menu);
4545	endwin();
4546	}
4547	</span></font>
4548	</pre></td>
4549	</tr>
4550	</table>
4551	</div>
4552	</div>
4553	<div class="SECT2">
4554	<hr>
4555	<h3 class="SECT2"><a name="MENUUSERPTR" id="MENUUSERPTR">17.9. The
4556	useful User Pointer</a></h3>
4557	<p>We can associate a user pointer with each item in the menu. It
4558	works the same way as user pointer in panels. It's not touched by
4559	menu system. You can store any thing you like in that. I usually
4560	use it to store the function to be executed when the menu option is
4561	chosen (It's selected and may be the user pressed
4562	<ENTER>);</p>
4563	<div class="EXAMPLE"><a name="MMEUS" id="MMEUS"></a>
4564	<p><b>Example 24. Menu User Pointer Usage</b></p>
4565	<table border="0" bgcolor="#E0E0E0" width="100%">
4566	<tr>
4567	<td>
4568	<pre class="PROGRAMLISTING">
4569	<font color="#000000"><span class=
4570	"INLINEMEDIAOBJECT">#include <curses.h>
4571	#include <menu.h>
4572
4573	#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4574	#define CTRLD 4
4575
4576	char *choices[] = {
4577	"Choice 1",
4578	"Choice 2",
4579	"Choice 3",
4580	"Choice 4",
4581	"Choice 5",
4582	"Choice 6",
4583	"Choice 7",
4584	"Exit",
4585	};
4586	void func(char *name);
4587
4588	int main()
4589	{ ITEM **my_items;
4590	int c;
4591	MENU *my_menu;
4592	int n_choices, i;
4593	ITEM *cur_item;
4594
4595	/* Initialize curses */
4596	initscr();
4597	start_color();
4598	cbreak();
4599	noecho();
4600	keypad(stdscr, TRUE);
4601	init_pair(1, COLOR_RED, COLOR_BLACK);
4602	init_pair(2, COLOR_GREEN, COLOR_BLACK);
4603	init_pair(3, COLOR_MAGENTA, COLOR_BLACK);
4604
4605	/* Initialize items */
4606	n_choices = ARRAY_SIZE(choices);
4607	my_items = (ITEM *)calloc(n_choices + 1, sizeof(ITEM ));
4608	for(i = 0; i < n_choices; ++i)
4609	{ my_items[i] = new_item(choices[i], choices[i]);
4610	/* Set the user pointer */
4611	set_item_userptr(my_items[i], func);
4612	}
4613	my_items[n_choices] = (ITEM *)NULL;
4614
4615	/* Create menu */
4616	my_menu = new_menu((ITEM **)my_items);
4617
4618	/* Post the menu */
4619	mvprintw(LINES - 3, 0, "Press <ENTER> to see the option selected");
4620	mvprintw(LINES - 2, 0, "Up and Down arrow keys to naviage (F1 to Exit)");
4621	post_menu(my_menu);
4622	refresh();
4623
4624	while((c = getch()) != KEY_F(1))
4625	{ switch(c)
4626	{ case KEY_DOWN:
4627	menu_driver(my_menu, REQ_DOWN_ITEM);
4628	break;
4629	case KEY_UP:
4630	menu_driver(my_menu, REQ_UP_ITEM);
4631	break;
4632	case 10: /* Enter */
4633	{ ITEM *cur;
4634	void (p)(char );
4635
4636	cur = current_item(my_menu);
4637	p = item_userptr(cur);
4638	p((char *)item_name(cur));
4639	pos_menu_cursor(my_menu);
4640	break;
4641	}
4642	break;
4643	}
4644	}
4645	unpost_menu(my_menu);
4646	for(i = 0; i < n_choices; ++i)
4647	free_item(my_items[i]);
4648	free_menu(my_menu);
4649	endwin();
4650	}
4651
4652	void func(char *name)
4653	{ move(20, 0);
4654	clrtoeol();
4655	mvprintw(20, 0, "Item selected is : %s", name);
4656	} </span></font>
4657	</pre></td>
4658	</tr>
4659	</table>
4660	</div>
4661	</div>
4662	</div>
4663	<div class="SECT1">
4664	<hr>
4665	<h2 class="SECT1"><a name="FORMS" id="FORMS">18. Forms
4666	Library</a></h2>
4667	<p>Well. If you have seen those forms on web pages which take input
4668	from users and do various kinds of things, you might be wondering
4669	how would any one create such forms in text mode display. It's
4670	quite difficult to write those nifty forms in plain ncurses. Forms
4671	library tries to provide a basic frame work to build and maintain
4672	forms with ease. It has lot of features(functions) which manage
4673	validation, dynamic expansion of fields etc.. Let's see it in full
4674	flow.</p>
4675	<p>A form is a collection of fields; each field can be either a
4676	label(static text) or a data-entry location. The forms also library
4677	provides functions to divide forms into multiple pages.</p>
4678	<div class="SECT2">
4679	<hr>
4680	<h3 class="SECT2"><a name="FORMBASICS" id="FORMBASICS">18.1. The
4681	Basics</a></h3>
4682	<p>Forms are created in much the same way as menus. First the
4683	fields related to the form are created with new_field(). You can
4684	set options for the fields, so that they can be displayed with some
4685	fancy attributes, validated before the field looses focus etc..
4686	Then the fields are attached to form. After this, the form can be
4687	posted to display and is ready to receive inputs. On the similar
4688	lines to menu_driver(), the form is manipulated with form_driver().
4689	We can send requests to form_driver to move focus to a certain
4690	field, move cursor to end of the field etc.. After the user enters
4691	values in the fields and validation done, form can be unposted and
4692	memory allocated can be freed.</p>
4693	<p>The general flow of control of a forms program looks like
4694	this.</p>
4695	<ol type="1">
4696	<li>
4697	<p>Initialize curses</p>
4698	</li>
4699	<li>
4700	<p>Create fields using new_field(). You can specify the height and
4701	width of the field, and its position on the form.</p>
4702	</li>
4703	<li>
4704	<p>Create the forms with new_form() by specifying the fields to be
4705	attached with.</p>
4706	</li>
4707	<li>
4708	<p>Post the form with form_post() and refresh the screen.</p>
4709	</li>
4710	<li>
4711	<p>Process the user requests with a loop and do necessary updates
4712	to form with form_driver.</p>
4713	</li>
4714	<li>
4715	<p>Unpost the menu with form_unpost()</p>
4716	</li>
4717	<li>
4718	<p>Free the memory allocated to menu by free_form()</p>
4719	</li>
4720	<li>
4721	<p>Free the memory allocated to the items with free_field()</p>
4722	</li>
4723	<li>
4724	<p>End curses</p>
4725	</li>
4726	</ol>
4727	<p>As you can see, working with forms library is much similar to
4728	handling menu library. The following examples will explore various
4729	aspects of form processing. Let's start the journey with a simple
4730	example. first.</p>
4731	</div>
4732	<div class="SECT2">
4733	<hr>
4734	<h3 class="SECT2"><a name="COMPILEFORMS" id="COMPILEFORMS">18.2.
4735	Compiling With the Forms Library</a></h3>
4736	<p>To use forms library functions, you have to include form.h and
4737	to link the program with forms library the flag -lform should be
4738	added along with -lncurses in that order.</p>
4739	<table border="0" bgcolor="#E0E0E0" width="100%">
4740	<tr>
4741	<td>
4742	<pre class="PROGRAMLISTING">
4743	<font color="#000000"> #include <form.h>
4744	.
4745	.
4746	.
4747
4748	compile and link: gcc <program file> -lform -lncurses</font>
4749	</pre></td>
4750	</tr>
4751	</table>
4752	<div class="EXAMPLE"><a name="FFOSI" id="FFOSI"></a>
4753	<p><b>Example 25. Forms Basics</b></p>
4754	<table border="0" bgcolor="#E0E0E0" width="100%">
4755	<tr>
4756	<td>
4757	<pre class="PROGRAMLISTING">
4758	<font color="#000000"><span class=
4759	"INLINEMEDIAOBJECT">#include <form.h>
4760
4761	int main()
4762	{ FIELD *field[3];
4763	FORM *my_form;
4764	int ch;
4765
4766	/* Initialize curses */
4767	initscr();
4768	cbreak();
4769	noecho();
4770	keypad(stdscr, TRUE);
4771
4772	/* Initialize the fields */
4773	field[0] = new_field(1, 10, 4, 18, 0, 0);
4774	field[1] = new_field(1, 10, 6, 18, 0, 0);
4775	field[2] = NULL;
4776
4777	/* Set field options */
4778	set_field_back(field[0], A_UNDERLINE); /* Print a line for the option */
4779	field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */
4780	/* Field is filled up */
4781	set_field_back(field[1], A_UNDERLINE);
4782	field_opts_off(field[1], O_AUTOSKIP);
4783
4784	/* Create the form and post it */
4785	my_form = new_form(field);
4786	post_form(my_form);
4787	refresh();
4788
4789	mvprintw(4, 10, "Value 1:");
4790	mvprintw(6, 10, "Value 2:");
4791	refresh();
4792
4793	/* Loop through to get user requests */
4794	while((ch = getch()) != KEY_F(1))
4795	{ switch(ch)
4796	{ case KEY_DOWN:
4797	/* Go to next field */
4798	form_driver(my_form, REQ_NEXT_FIELD);
4799	/* Go to the end of the present buffer */
4800	/* Leaves nicely at the last character */
4801	form_driver(my_form, REQ_END_LINE);
4802	break;
4803	case KEY_UP:
4804	/* Go to previous field */
4805	form_driver(my_form, REQ_PREV_FIELD);
4806	form_driver(my_form, REQ_END_LINE);
4807	break;
4808	default:
4809	/* If this is a normal character, it gets */
4810	/* Printed */
4811	form_driver(my_form, ch);
4812	break;
4813	}
4814	}
4815
4816	/* Un post form and free the memory */
4817	unpost_form(my_form);
4818	free_form(my_form);
4819	free_field(field[0]);
4820	free_field(field[1]);
4821
4822	endwin();
4823	return 0;
4824	}</span></font>
4825	</pre></td>
4826	</tr>
4827	</table>
4828	</div>
4829	<p>Above example is pretty straight forward. It creates two fields
4830	with <var class="LITERAL">new_field()</var>. new_field() takes
4831	height, width, starty, startx, number of offscreen rows and number
4832	of additional working buffers. The fifth argument number of
4833	offscreen rows specifies how much of the field to be shown. If it
4834	is zero, the entire field is always displayed otherwise the form
4835	will be scrollable when the user accesses not displayed parts of
4836	the field. The forms library allocates one buffer per field to
4837	store the data user enters. Using the last parameter to new_field()
4838	we can specify it to allocate some additional buffers. These can be
4839	used for any purpose you like.</p>
4840	<p>After creating the fields, back ground attribute of both of them
4841	is set to an underscore with set_field_back(). The AUTOSKIP option
4842	is turned off using field_opts_off(). If this option is turned on,
4843	focus will move to the next field in the form once the active field
4844	is filled up completely.</p>
4845	<p>After attaching the fields to the form, it is posted. Here on,
4846	user inputs are processed in the while loop, by making
4847	corresponding requests to form_driver. The details of all the
4848	requests to the form_driver() are explained later.</p>
4849	</div>
4850	<div class="SECT2">
4851	<hr>
4852	<h3 class="SECT2"><a name="PLAYFIELDS" id="PLAYFIELDS">18.3.
4853	Playing with Fields</a></h3>
4854	<p>Each form field is associated with a lot of attributes. They can
4855	be manipulated to get the required effect and to have fun !!!. So
4856	why wait?</p>
4857	<div class="SECT3">
4858	<hr>
4859	<h4 class="SECT3"><a name="FETCHINFO" id="FETCHINFO">18.3.1.
4860	Fetching Size and Location of Field</a></h4>
4861	<p>The parameters we have given at the time of creation of a field
4862	can be retrieved with field_info(). It returns height, width,
4863	starty, startx, number of offscreen rows, and number of additional
4864	buffers into the parameters given to it. It is a sort of inverse of
4865	new_field().</p>
4866	<table border="0" bgcolor="#E0E0E0" width="100%">
4867	<tr>
4868	<td>
4869	<pre class="PROGRAMLISTING">
4870	<font color=
4871	"#000000">int field_info( FIELD field, / field from which to fetch */
4872	int height, int width, /* field size */
4873	int top, int left, /* upper left corner */
4874	int offscreen, / number of offscreen rows */
4875	int nbuf); / number of working buffers */</font>
4876	</pre></td>
4877	</tr>
4878	</table>
4879	</div>
4880	<div class="SECT3">
4881	<hr>
4882	<h4 class="SECT3"><a name="MOVEFIELD" id="MOVEFIELD">18.3.2. Moving
4883	the field</a></h4>
4884	<p>The location of the field can be moved to a different position
4885	with move_field().</p>
4886	<table border="0" bgcolor="#E0E0E0" width="100%">
4887	<tr>
4888	<td>
4889	<pre class="PROGRAMLISTING">
4890	<font color=
4891	"#000000">int move_field( FIELD field, / field to alter */
4892	int top, int left); /* new upper-left corner */</font>
4893	</pre></td>
4894	</tr>
4895	</table>
4896	<p>As usual, the changed position can be queried with
4897	field_infor().</p>
4898	</div>
4899	<div class="SECT3">
4900	<hr>
4901	<h4 class="SECT3"><a name="JUSTIFYFIELD" id="JUSTIFYFIELD">18.3.3.
4902	Field Justification</a></h4>
4903	<p>The justification to be done for the field can be fixed using
4904	the function set_field_just().</p>
4905	<table border="0" bgcolor="#E0E0E0" width="100%">
4906	<tr>
4907	<td>
4908	<pre class="PROGRAMLISTING">
4909	<font color=
4910	"#000000"> int set_field_just(FIELD field, / field to alter */
4911	int justmode); /* mode to set */
4912	int field_just(FIELD field); / fetch justify mode of field */</font>
4913	</pre></td>
4914	</tr>
4915	</table>
4916	<p>The justification mode valued accepted and returned by these
4917	functions are NO_JUSTIFICATION, JUSTIFY_RIGHT, JUSTIFY_LEFT, or
4918	JUSTIFY_CENTER.</p>
4919	</div>
4920	<div class="SECT3">
4921	<hr>
4922	<h4 class="SECT3"><a name="FIELDDISPATTRIB" id=
4923	"FIELDDISPATTRIB">18.3.4. Field Display Attributes</a></h4>
4924	<p>As you have seen, in the above example, display attribute for
4925	the fields can be set with set_field_fore() and setfield_back().
4926	These functions set foreground and background attribute of the
4927	fields. You can also specify a pad character which will be filled
4928	in the unfilled portion of the field. The pad character is set with
4929	a call to set_field_pad(). Default pad value is a space. The
4930	functions field_fore(), field_back, field_pad() can be used to
4931	query the present foreground, background attributes and pad
4932	character for the field. The following list gives the usage of
4933	functions.</p>
4934	<table border="0" bgcolor="#E0E0E0" width="100%">
4935	<tr>
4936	<td>
4937	<pre class="PROGRAMLISTING">
4938	<font color=
4939	"#000000"> int set_field_fore(FIELD field, / field to alter */
4940	chtype attr); /* attribute to set */
4941
4942	chtype field_fore(FIELD field); / field to query */
4943	/* returns foreground attribute */
4944
4945	int set_field_back(FIELD field, / field to alter */
4946	chtype attr); /* attribute to set */
4947
4948	chtype field_back(FIELD field); / field to query */
4949	/* returns background attribute */
4950
4951	int set_field_pad(FIELD field, / field to alter */
4952	int pad); /* pad character to set */
4953
4954	chtype field_pad(FIELD field); / field to query */
4955	/* returns present pad character */ </font>
4956	</pre></td>
4957	</tr>
4958	</table>
4959	<p>Though above functions seem quite simple, using colors with
4960	set_field_fore() may be frustrating in the beginning. Let me first
4961	explain about foreground and background attributes of a field. The
4962	foreground attribute is associated with the character. That means a
4963	character in the field is printed with the attribute you have set
4964	with set_field_fore(). Background attribute is the attribute used
4965	to fill background of field, whether any character is there or not.
4966	So what about colors? Since colors are always defined in pairs,
4967	what is the right way to display colored fields? Here's an example
4968	clarifying color attributes.</p>
4969	<div class="EXAMPLE"><a name="FFOAT" id="FFOAT"></a>
4970	<p><b>Example 26. Form Attributes example</b></p>
4971	<table border="0" bgcolor="#E0E0E0" width="100%">
4972	<tr>
4973	<td>
4974	<pre class="PROGRAMLISTING">
4975	<font color="#000000"><span class=
4976	"INLINEMEDIAOBJECT">#include <form.h>
4977
4978	int main()
4979	{ FIELD *field[3];
4980	FORM *my_form;
4981	int ch;
4982
4983	/* Initialize curses */
4984	initscr();
4985	start_color();
4986	cbreak();
4987	noecho();
4988	keypad(stdscr, TRUE);
4989
4990	/* Initialize few color pairs */
4991	init_pair(1, COLOR_WHITE, COLOR_BLUE);
4992	init_pair(2, COLOR_WHITE, COLOR_BLUE);
4993
4994	/* Initialize the fields */
4995	field[0] = new_field(1, 10, 4, 18, 0, 0);
4996	field[1] = new_field(1, 10, 6, 18, 0, 0);
4997	field[2] = NULL;
4998
4999	/* Set field options */
5000	set_field_fore(field[0], COLOR_PAIR(1));/* Put the field with blue background */
5001	set_field_back(field[0], COLOR_PAIR(2));/* and white foreground (characters */
5002	/* are printed in white */
5003	field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */
5004	/* Field is filled up */
5005	set_field_back(field[1], A_UNDERLINE);
5006	field_opts_off(field[1], O_AUTOSKIP);
5007
5008	/* Create the form and post it */
5009	my_form = new_form(field);
5010	post_form(my_form);
5011	refresh();
5012
5013	set_current_field(my_form, field[0]); /* Set focus to the colored field */
5014	mvprintw(4, 10, "Value 1:");
5015	mvprintw(6, 10, "Value 2:");
5016	mvprintw(LINES - 2, 0, "Use UP, DOWN arrow keys to switch between fields");
5017	refresh();
5018
5019	/* Loop through to get user requests */
5020	while((ch = getch()) != KEY_F(1))
5021	{ switch(ch)
5022	{ case KEY_DOWN:
5023	/* Go to next field */
5024	form_driver(my_form, REQ_NEXT_FIELD);
5025	/* Go to the end of the present buffer */
5026	/* Leaves nicely at the last character */
5027	form_driver(my_form, REQ_END_LINE);
5028	break;
5029	case KEY_UP:
5030	/* Go to previous field */
5031	form_driver(my_form, REQ_PREV_FIELD);
5032	form_driver(my_form, REQ_END_LINE);
5033	break;
5034	default:
5035	/* If this is a normal character, it gets */
5036	/* Printed */
5037	form_driver(my_form, ch);
5038	break;
5039	}
5040	}
5041
5042	/* Un post form and free the memory */
5043	unpost_form(my_form);
5044	free_form(my_form);
5045	free_field(field[0]);
5046	free_field(field[1]);
5047
5048	endwin();
5049	return 0;
5050	}</span></font>
5051	</pre></td>
5052	</tr>
5053	</table>
5054	</div>
5055	<p>Play with the color pairs and try to understand the foreground
5056	and background attributes. In my programs using color attributes, I
5057	usually set only the background with set_field_back(). Curses
5058	simply doesn't allow defining individual color attributes.</p>
5059	</div>
5060	<div class="SECT3">
5061	<hr>
5062	<h4 class="SECT3"><a name="FIELDOPTIONBITS" id=
5063	"FIELDOPTIONBITS">18.3.5. Field Option Bits</a></h4>
5064	<p>There is also a large collection of field option bits you can
5065	set to control various aspects of forms processing. You can
5066	manipulate them with these functions:</p>
5067	<table border="0" bgcolor="#E0E0E0" width="100%">
5068	<tr>
5069	<td>
5070	<pre class="PROGRAMLISTING">
5071	<font color=
5072	"#000000">int set_field_opts(FIELD field, / field to alter */
5073	int attr); /* attribute to set */
5074
5075	int field_opts_on(FIELD field, / field to alter */
5076	int attr); /* attributes to turn on */
5077
5078	int field_opts_off(FIELD field, / field to alter */
5079	int attr); /* attributes to turn off */
5080
5081	int field_opts(FIELD field); / field to query */ </font>
5082	</pre></td>
5083	</tr>
5084	</table>
5085	<p>The function set_field_opts() can be used to directly set
5086	attributes of a field or you can choose to switch a few attributes
5087	on and off with field_opts_on() and field_opts_off() selectively.
5088	Anytime you can query the attributes of a field with field_opts().
5089	The following is the list of available options. By default, all
5090	options are on.</p>
5091	<div class="VARIABLELIST">
5092	<dl>
5093	<dt>O_VISIBLE</dt>
5094	<dd>
5095	<p>Controls whether the field is visible on the screen. Can be used
5096	during form processing to hide or pop up fields depending on the
5097	value of parent fields.</p>
5098	</dd>
5099	<dt>O_ACTIVE</dt>
5100	<dd>
5101	<p>Controls whether the field is active during forms processing
5102	(i.e. visited by form navigation keys). Can be used to make labels
5103	or derived fields with buffer values alterable by the forms
5104	application, not the user.</p>
5105	</dd>
5106	<dt>O_PUBLIC</dt>
5107	<dd>
5108	<p>Controls whether data is displayed during field entry. If this
5109	option is turned off on a field, the library will accept and edit
5110	data in that field, but it will not be displayed and the visible
5111	field cursor will not move. You can turn off the O_PUBLIC bit to
5112	define password fields.</p>
5113	</dd>
5114	<dt>O_EDIT</dt>
5115	<dd>
5116	<p>Controls whether the field's data can be modified. When this
5117	option is off, all editing requests except <var class=
5118	"LITERAL">REQ_PREV_CHOICE</var> and <var class=
5119	"LITERAL">REQ_NEXT_CHOICE</var>will fail. Such read-only fields may
5120	be useful for help messages.</p>
5121	</dd>
5122	<dt>O_WRAP</dt>
5123	<dd>
5124	<p>Controls word-wrapping in multi-line fields. Normally, when any
5125	character of a (blank-separated) word reaches the end of the
5126	current line, the entire word is wrapped to the next line (assuming
5127	there is one). When this option is off, the word will be split
5128	across the line break.</p>
5129	</dd>
5130	<dt>O_BLANK</dt>
5131	<dd>
5132	<p>Controls field blanking. When this option is on, entering a
5133	character at the first field position erases the entire field
5134	(except for the just-entered character).</p>
5135	</dd>
5136	<dt>O_AUTOSKIP</dt>
5137	<dd>
5138	<p>Controls automatic skip to next field when this one fills.
5139	Normally, when the forms user tries to type more data into a field
5140	than will fit, the editing location jumps to next field. When this
5141	option is off, the user's cursor will hang at the end of the field.
5142	This option is ignored in dynamic fields that have not reached
5143	their size limit.</p>
5144	</dd>
5145	<dt>O_NULLOK</dt>
5146	<dd>
5147	<p>Controls whether validation is applied to blank fields.
5148	Normally, it is not; the user can leave a field blank without
5149	invoking the usual validation check on exit. If this option is off
5150	on a field, exit from it will invoke a validation check.</p>
5151	</dd>
5152	<dt>O_PASSOK</dt>
5153	<dd>
5154	<p>Controls whether validation occurs on every exit, or only after
5155	the field is modified. Normally the latter is true. Setting
5156	O_PASSOK may be useful if your field's validation function may
5157	change during forms processing.</p>
5158	</dd>
5159	<dt>O_STATIC</dt>
5160	<dd>
5161	<p>Controls whether the field is fixed to its initial dimensions.
5162	If you turn this off, the field becomes dynamic and will stretch to
5163	fit entered data.</p>
5164	</dd>
5165	</dl>
5166	</div>
5167	<p>A field's options cannot be changed while the field is currently
5168	selected. However, options may be changed on posted fields that are
5169	not current.</p>
5170	<p>The option values are bit-masks and can be composed with
5171	logical-or in the obvious way. You have seen the usage of switching
5172	off O_AUTOSKIP option. The following example clarifies usage of
5173	some more options. Other options are explained where
5174	appropriate.</p>
5175	<div class="EXAMPLE"><a name="FFOOP" id="FFOOP"></a>
5176	<p><b>Example 27. Field Options Usage example</b></p>
5177	<table border="0" bgcolor="#E0E0E0" width="100%">
5178	<tr>
5179	<td>
5180	<pre class="PROGRAMLISTING">
5181	<font color="#000000"><span class=
5182	"INLINEMEDIAOBJECT">#include <form.h>
5183
5184	#define STARTX 15
5185	#define STARTY 4
5186	#define WIDTH 25
5187
5188	#define N_FIELDS 3
5189
5190	int main()
5191	{ FIELD *field[N_FIELDS];
5192	FORM *my_form;
5193	int ch, i;
5194
5195	/* Initialize curses */
5196	initscr();
5197	cbreak();
5198	noecho();
5199	keypad(stdscr, TRUE);
5200
5201	/* Initialize the fields */
5202	for(i = 0; i < N_FIELDS - 1; ++i)
5203	field[i] = new_field(1, WIDTH, STARTY + i * 2, STARTX, 0, 0);
5204	field[N_FIELDS - 1] = NULL;
5205
5206	/* Set field options */
5207	set_field_back(field[1], A_UNDERLINE); /* Print a line for the option */
5208
5209	field_opts_off(field[0], O_ACTIVE); /* This field is a static label */
5210	field_opts_off(field[1], O_PUBLIC); /* This filed is like a password field*/
5211	field_opts_off(field[1], O_AUTOSKIP); /* To avoid entering the same field */
5212	/* after last character is entered */
5213
5214	/* Create the form and post it */
5215	my_form = new_form(field);
5216	post_form(my_form);
5217	refresh();
5218
5219	set_field_just(field[0], JUSTIFY_CENTER); /* Center Justification */
5220	set_field_buffer(field[0], 0, "This is a static Field");
5221	/* Initialize the field */
5222	mvprintw(STARTY, STARTX - 10, "Field 1:");
5223	mvprintw(STARTY + 2, STARTX - 10, "Field 2:");
5224	refresh();
5225
5226	/* Loop through to get user requests */
5227	while((ch = getch()) != KEY_F(1))
5228	{ switch(ch)
5229	{ case KEY_DOWN:
5230	/* Go to next field */
5231	form_driver(my_form, REQ_NEXT_FIELD);
5232	/* Go to the end of the present buffer */
5233	/* Leaves nicely at the last character */
5234	form_driver(my_form, REQ_END_LINE);
5235	break;
5236	case KEY_UP:
5237	/* Go to previous field */
5238	form_driver(my_form, REQ_PREV_FIELD);
5239	form_driver(my_form, REQ_END_LINE);
5240	break;
5241	default:
5242	/* If this is a normal character, it gets */
5243	/* Printed */
5244	form_driver(my_form, ch);
5245	break;
5246	}
5247	}
5248
5249	/* Un post form and free the memory */
5250	unpost_form(my_form);
5251	free_form(my_form);
5252	free_field(field[0]);
5253	free_field(field[1]);
5254
5255	endwin();
5256	return 0;
5257	}</span></font>
5258	</pre></td>
5259	</tr>
5260	</table>
5261	</div>
5262	<p>This example, though useless, shows the usage of options. If
5263	used properly, they can present information very effectively in a
5264	form. The second field being not O_PUBLIC, does not show the
5265	characters you are typing.</p>
5266	</div>
5267	<div class="SECT3">
5268	<hr>
5269	<h4 class="SECT3"><a name="FIELDSTATUS" id="FIELDSTATUS">18.3.6.
5270	Field Status</a></h4>
5271	<p>The field status specifies whether the field has got edited or
5272	not. It is initially set to FALSE and when user enters something
5273	and the data buffer gets modified it becomes TRUE. So a field's
5274	status can be queried to find out whether it has been modified or
5275	not. The following functions can assist in those operations.</p>
5276	<table border="0" bgcolor="#E0E0E0" width="100%">
5277	<tr>
5278	<td>
5279	<pre class="PROGRAMLISTING">
5280	<font color=
5281	"#000000">int set_field_status(FIELD field, / field to alter */
5282	int status); /* status to set */
5283
5284	int field_status(FIELD field); / fetch status of field */</font>
5285	</pre></td>
5286	</tr>
5287	</table>
5288	<p>It's better to check the field's status only after after leaving
5289	the field, as data buffer might not have been updated yet as the
5290	validation is still due. To guarantee that right status is
5291	returned, call field_status() either (1) in the field's exit
5292	validation check routine, (2) from the field's or form's
5293	initialization or termination hooks, or (3) just after a
5294	REQ_VALIDATION request has been processed by the forms driver</p>
5295	</div>
5296	<div class="SECT3">
5297	<hr>
5298	<h4 class="SECT3"><a name="FIELDUSERPTR" id="FIELDUSERPTR">18.3.7.
5299	Field User Pointer</a></h4>
5300	<p>Every field structure contains one pointer that can be used by
5301	the user for various purposes. It is not touched by forms library
5302	and can be used for any purpose by the user. The following
5303	functions set and fetch user pointer.</p>
5304	<table border="0" bgcolor="#E0E0E0" width="100%">
5305	<tr>
5306	<td>
5307	<pre class="PROGRAMLISTING">
5308	<font color="#000000">int set_field_userptr(FIELD *field,
5309	char userptr); / the user pointer you wish to associate */
5310	/* with the field */
5311
5312	char field_userptr(FIELD field); /* fetch user pointer of the field */</font>
5313	</pre></td>
5314	</tr>
5315	</table>
5316	</div>
5317	<div class="SECT3">
5318	<hr>
5319	<h4 class="SECT3"><a name="VARIABLESIZEFIELDS" id=
5320	"VARIABLESIZEFIELDS">18.3.8. Variable-Sized Fields</a></h4>
5321	<p>If you want a dynamically changing field with variable width,
5322	this is the feature you want to put to full use. This will allow
5323	the user to enter more data than the original size of the field and
5324	let the field grow. According to the field orientation it will
5325	scroll horizontally or vertically to incorporate the new data.</p>
5326	<p>To make a field dynamically growable, the option O_STATIC should
5327	be turned off. This can be done with a</p>
5328	<table border="0" bgcolor="#E0E0E0" width="100%">
5329	<tr>
5330	<td>
5331	<pre class="PROGRAMLISTING">
5332	<font color=
5333	"#000000"> field_opts_off(field_pointer, O_STATIC);</font>
5334	</pre></td>
5335	</tr>
5336	</table>
5337	<p>But it's usually not advisable to allow a field to grow
5338	infinitely. You can set a maximum limit to the growth of the field
5339	with</p>
5340	<table border="0" bgcolor="#E0E0E0" width="100%">
5341	<tr>
5342	<td>
5343	<pre class="PROGRAMLISTING">
5344	<font color=
5345	"#000000">int set_max_field(FIELD field, / Field on which to operate */
5346	int max_growth); /* maximum growth allowed for the field */</font>
5347	</pre></td>
5348	</tr>
5349	</table>
5350	<p>The field info for a dynamically growable field can be retrieved
5351	by</p>
5352	<table border="0" bgcolor="#E0E0E0" width="100%">
5353	<tr>
5354	<td>
5355	<pre class="PROGRAMLISTING">
5356	<font color=
5357	"#000000">int dynamic_field_info( FIELD field, / Field on which to operate */
5358	int prows, / number of rows will be filled in this */
5359	int pcols, / number of columns will be filled in this*/
5360	int pmax) / maximum allowable growth will be filled */
5361	/* in this */</font>
5362	</pre></td>
5363	</tr>
5364	</table>
5365	Though field_info work as usual, it is advisable to use this
5366	function to get the proper attributes of a dynamically growable
5367	field.
5368	<p>Recall the library routine new_field; a new field created with
5369	height set to one will be defined to be a one line field. A new
5370	field created with height greater than one will be defined to be a
5371	multi line field.</p>
5372	<p>A one line field with O_STATIC turned off (dynamically growable
5373	field) will contain a single fixed row, but the number of columns
5374	can increase if the user enters more data than the initial field
5375	will hold. The number of columns displayed will remain fixed and
5376	the additional data will scroll horizontally.</p>
5377	<p>A multi line field with O_STATIC turned off (dynamically
5378	growable field) will contain a fixed number of columns, but the
5379	number of rows can increase if the user enters more data than the
5380	initial field will hold. The number of rows displayed will remain
5381	fixed and the additional data will scroll vertically.</p>
5382	<p>The above two paragraphs pretty much describe a dynamically
5383	growable field's behavior. The way other parts of forms library
5384	behaves is described below:</p>
5385	<ol type="1">
5386	<li>
5387	<p>The field option O_AUTOSKIP will be ignored if the option
5388	O_STATIC is off and there is no maximum growth specified for the
5389	field. Currently, O_AUTOSKIP generates an automatic REQ_NEXT_FIELD
5390	form driver request when the user types in the last character
5391	position of a field. On a growable field with no maximum growth
5392	specified, there is no last character position. If a maximum growth
5393	is specified, the O_AUTOSKIP option will work as normal if the
5394	field has grown to its maximum size.</p>
5395	</li>
5396	<li>
5397	<p>The field justification will be ignored if the option O_STATIC
5398	is off. Currently, set_field_just can be used to JUSTIFY_LEFT,
5399	JUSTIFY_RIGHT, JUSTIFY_CENTER the contents of a one line field. A
5400	growable one line field will, by definition, grow and scroll
5401	horizontally and may contain more data than can be justified. The
5402	return from field_just will be unchanged.</p>
5403	</li>
5404	<li>
5405	<p>The overloaded form driver request REQ_NEW_LINE will operate the
5406	same way regardless of the O_NL_OVERLOAD form option if the field
5407	option O_STATIC is off and there is no maximum growth specified for
5408	the field. Currently, if the form option O_NL_OVERLOAD is on,
5409	REQ_NEW_LINE implicitly generates a REQ_NEXT_FIELD if called from
5410	the last line of a field. If a field can grow without bound, there
5411	is no last line, so REQ_NEW_LINE will never implicitly generate a
5412	REQ_NEXT_FIELD. If a maximum growth limit is specified and the
5413	O_NL_OVERLOAD form option is on, REQ_NEW_LINE will only implicitly
5414	generate REQ_NEXT_FIELD if the field has grown to its maximum size
5415	and the user is on the last line.</p>
5416	</li>
5417	<li>
5418	<p>The library call dup_field will work as usual; it will duplicate
5419	the field, including the current buffer size and contents of the
5420	field being duplicated. Any specified maximum growth will also be
5421	duplicated.</p>
5422	</li>
5423	<li>
5424	<p>The library call link_field will work as usual; it will
5425	duplicate all field attributes and share buffers with the field
5426	being linked. If the O_STATIC field option is subsequently changed
5427	by a field sharing buffers, how the system reacts to an attempt to
5428	enter more data into the field than the buffer will currently hold
5429	will depend on the setting of the option in the current field.</p>
5430	</li>
5431	<li>
5432	<p>The library call field_info will work as usual; the variable
5433	nrow will contain the value of the original call to new_field. The
5434	user should use dynamic_field_info, described above, to query the
5435	current size of the buffer.</p>
5436	</li>
5437	</ol>
5438	<p>Some of the above points make sense only after explaining form
5439	driver. We will be looking into that in next few sections.</p>
5440	</div>
5441	</div>
5442	<div class="SECT2">
5443	<hr>
5444	<h3 class="SECT2"><a name="FORMWINDOWS" id="FORMWINDOWS">18.4. Form
5445	Windows</a></h3>
5446	<p>The form windows concept is pretty much similar to menu windows.
5447	Every form is associated with a main window and a sub window. The
5448	form main window displays any title or border associated or
5449	whatever the user wishes. Then the sub window contains all the
5450	fields and displays them according to their position. This gives
5451	the flexibility of manipulating fancy form displaying very
5452	easily.</p>
5453	<p>Since this is pretty much similar to menu windows, I am
5454	providing an example with out much explanation. The functions are
5455	similar and they work the same way.</p>
5456	<div class="EXAMPLE"><a name="FFOWI" id="FFOWI"></a>
5457	<p><b>Example 28. Form Windows Example</b></p>
5458	<table border="0" bgcolor="#E0E0E0" width="100%">
5459	<tr>
5460	<td>
5461	<pre class="PROGRAMLISTING">
5462	<font color="#000000"><span class=
5463	"INLINEMEDIAOBJECT">#include <form.h>
5464
5465	void print_in_middle(WINDOW win, int starty, int startx, int width, char string, chtype color);
5466
5467	int main()
5468	{
5469	FIELD *field[3];
5470	FORM *my_form;
5471	WINDOW *my_form_win;
5472	int ch, rows, cols;
5473
5474	/* Initialize curses */
5475	initscr();
5476	start_color();
5477	cbreak();
5478	noecho();
5479	keypad(stdscr, TRUE);
5480
5481	/* Initialize few color pairs */
5482	init_pair(1, COLOR_RED, COLOR_BLACK);
5483
5484	/* Initialize the fields */
5485	field[0] = new_field(1, 10, 6, 1, 0, 0);
5486	field[1] = new_field(1, 10, 8, 1, 0, 0);
5487	field[2] = NULL;
5488
5489	/* Set field options */
5490	set_field_back(field[0], A_UNDERLINE);
5491	field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */
5492	/* Field is filled up */
5493	set_field_back(field[1], A_UNDERLINE);
5494	field_opts_off(field[1], O_AUTOSKIP);
5495
5496	/* Create the form and post it */
5497	my_form = new_form(field);
5498
5499	/* Calculate the area required for the form */
5500	scale_form(my_form, &rows, &cols);
5501
5502	/* Create the window to be associated with the form */
5503	my_form_win = newwin(rows + 4, cols + 4, 4, 4);
5504	keypad(my_form_win, TRUE);
5505
5506	/* Set main window and sub window */
5507	set_form_win(my_form, my_form_win);
5508	set_form_sub(my_form, derwin(my_form_win, rows, cols, 2, 2));
5509
5510	/* Print a border around the main window and print a title */
5511	box(my_form_win, 0, 0);
5512	print_in_middle(my_form_win, 1, 0, cols + 4, "My Form", COLOR_PAIR(1));
5513
5514	post_form(my_form);
5515	wrefresh(my_form_win);
5516
5517	mvprintw(LINES - 2, 0, "Use UP, DOWN arrow keys to switch between fields");
5518	refresh();
5519
5520	/* Loop through to get user requests */
5521	while((ch = wgetch(my_form_win)) != KEY_F(1))
5522	{ switch(ch)
5523	{ case KEY_DOWN:
5524	/* Go to next field */
5525	form_driver(my_form, REQ_NEXT_FIELD);
5526	/* Go to the end of the present buffer */
5527	/* Leaves nicely at the last character */
5528	form_driver(my_form, REQ_END_LINE);
5529	break;
5530	case KEY_UP:
5531	/* Go to previous field */
5532	form_driver(my_form, REQ_PREV_FIELD);
5533	form_driver(my_form, REQ_END_LINE);
5534	break;
5535	default:
5536	/* If this is a normal character, it gets */
5537	/* Printed */
5538	form_driver(my_form, ch);
5539	break;
5540	}
5541	}
5542
5543	/* Un post form and free the memory */
5544	unpost_form(my_form);
5545	free_form(my_form);
5546	free_field(field[0]);
5547	free_field(field[1]);
5548
5549	endwin();
5550	return 0;
5551	}
5552
5553	void print_in_middle(WINDOW win, int starty, int startx, int width, char string, chtype color)
5554	{ int length, x, y;
5555	float temp;
5556
5557	if(win == NULL)
5558	win = stdscr;
5559	getyx(win, y, x);
5560	if(startx != 0)
5561	x = startx;
5562	if(starty != 0)
5563	y = starty;
5564	if(width == 0)
5565	width = 80;
5566
5567	length = strlen(string);
5568	temp = (width - length)/ 2;
5569	x = startx + (int)temp;
5570	wattron(win, color);
5571	mvwprintw(win, y, x, "%s", string);
5572	wattroff(win, color);
5573	refresh();
5574	}</span></font>
5575	</pre></td>
5576	</tr>
5577	</table>
5578	</div>
5579	</div>
5580	<div class="SECT2">
5581	<hr>
5582	<h3 class="SECT2"><a name="FILEDVALIDATE" id="FILEDVALIDATE">18.5.
5583	Field Validation</a></h3>
5584	<p>By default, a field will accept any data input by the user. It
5585	is possible to attach validation to the field. Then any attempt by
5586	the user to leave the field, while it contains data that doesn't
5587	match the validation type will fail. Some validation types also
5588	have a character-validity check for each time a character is
5589	entered in the field.</p>
5590	<p>Validation can be attached to a field with the following
5591	function.</p>
5592	<table border="0" bgcolor="#E0E0E0" width="100%">
5593	<tr>
5594	<td>
5595	<pre class="PROGRAMLISTING">
5596	<font color=
5597	"#000000">int set_field_type(FIELD field, / field to alter */
5598	FIELDTYPE ftype, / type to associate */
5599	...); /* additional arguments*/</font>
5600	</pre></td>
5601	</tr>
5602	</table>
5603	Once set, the validation type for a field can be queried with
5604	<table border="0" bgcolor="#E0E0E0" width="100%">
5605	<tr>
5606	<td>
5607	<pre class="PROGRAMLISTING">
5608	<font color=
5609	"#000000">FIELDTYPE field_type(FIELD field); /* field to query */</font>
5610	</pre></td>
5611	</tr>
5612	</table>
5613	<p>The form driver validates the data in a field only when data is
5614	entered by the end-user. Validation does not occur when</p>
5615	<ul>
5616	<li>
5617	<p>the application program changes the field value by calling
5618	set_field_buffer.</p>
5619	</li>
5620	<li>
5621	<p>linked field values are changed indirectly -- by changing the
5622	field to which they are linked</p>
5623	</li>
5624	</ul>
5625	<p>The following are the pre-defined validation types. You can also
5626	specify custom validation, though it's a bit tricky and
5627	cumbersome.</p>
5628	<h1 class="BRIDGEHEAD"><a name="AEN1069" id=
5629	"AEN1069"></a>TYPE_ALPHA</h1>
5630	<p>This field type accepts alphabetic data; no blanks, no digits,
5631	no special characters (this is checked at character-entry time). It
5632	is set up with:</p>
5633	<table border="0" bgcolor="#E0E0E0" width="100%">
5634	<tr>
5635	<td>
5636	<pre class="PROGRAMLISTING">
5637	<font color=
5638	"#000000">int set_field_type(FIELD field, / field to alter */
5639	TYPE_ALPHA, /* type to associate */
5640	int width); /* maximum width of field */</font>
5641	</pre></td>
5642	</tr>
5643	</table>
5644	<p>The width argument sets a minimum width of data. The user has to
5645	enter at-least width number of characters before he can leave the
5646	field. Typically you'll want to set this to the field width; if
5647	it's greater than the field width, the validation check will always
5648	fail. A minimum width of zero makes field completion optional.</p>
5649	<h1 class="BRIDGEHEAD"><a name="AEN1073" id=
5650	"AEN1073"></a>TYPE_ALNUM</h1>
5651	<p>This field type accepts alphabetic data and digits; no blanks,
5652	no special characters (this is checked at character-entry time). It
5653	is set up with:</p>
5654	<table border="0" bgcolor="#E0E0E0" width="100%">
5655	<tr>
5656	<td>
5657	<pre class="PROGRAMLISTING">
5658	<font color=
5659	"#000000">int set_field_type(FIELD field, / field to alter */
5660	TYPE_ALNUM, /* type to associate */
5661	int width); /* maximum width of field */</font>
5662	</pre></td>
5663	</tr>
5664	</table>
5665	<p>The width argument sets a minimum width of data. As with
5666	TYPE_ALPHA, typically you'll want to set this to the field width;
5667	if it's greater than the field width, the validation check will
5668	always fail. A minimum width of zero makes field completion
5669	optional.</p>
5670	<h1 class="BRIDGEHEAD"><a name="AEN1077" id=
5671	"AEN1077"></a>TYPE_ENUM</h1>
5672	<p>This type allows you to restrict a field's values to be among a
5673	specified set of string values (for example, the two-letter postal
5674	codes for U.S. states). It is set up with:</p>
5675	<table border="0" bgcolor="#E0E0E0" width="100%">
5676	<tr>
5677	<td>
5678	<pre class="PROGRAMLISTING">
5679	<font color=
5680	"#000000">int set_field_type(FIELD field, / field to alter */
5681	TYPE_ENUM, /* type to associate */
5682	char *valuelist; / list of possible values */
5683	int checkcase; /* case-sensitive? */
5684	int checkunique); /* must specify uniquely? */</font>
5685	</pre></td>
5686	</tr>
5687	</table>
5688	<p>The valuelist parameter must point at a NULL-terminated list of
5689	valid strings. The checkcase argument, if true, makes comparison
5690	with the string case-sensitive.</p>
5691	<p>When the user exits a TYPE_ENUM field, the validation procedure
5692	tries to complete the data in the buffer to a valid entry. If a
5693	complete choice string has been entered, it is of course valid. But
5694	it is also possible to enter a prefix of a valid string and have it
5695	completed for you.</p>
5696	<p>By default, if you enter such a prefix and it matches more than
5697	one value in the string list, the prefix will be completed to the
5698	first matching value. But the checkunique argument, if true,
5699	requires prefix matches to be unique in order to be valid.</p>
5700	<p>The REQ_NEXT_CHOICE and REQ_PREV_CHOICE input requests can be
5701	particularly useful with these fields.</p>
5702	<h1 class="BRIDGEHEAD"><a name="AEN1084" id=
5703	"AEN1084"></a>TYPE_INTEGER</h1>
5704	<p>This field type accepts an integer. It is set up as follows:</p>
5705	<table border="0" bgcolor="#E0E0E0" width="100%">
5706	<tr>
5707	<td>
5708	<pre class="PROGRAMLISTING">
5709	<font color=
5710	"#000000">int set_field_type(FIELD field, / field to alter */
5711	TYPE_INTEGER, /* type to associate */
5712	int padding, /* # places to zero-pad to */
5713	int vmin, int vmax); /* valid range */</font>
5714	</pre></td>
5715	</tr>
5716	</table>
5717	<p>Valid characters consist of an optional leading minus and
5718	digits. The range check is performed on exit. If the range maximum
5719	is less than or equal to the minimum, the range is ignored.</p>
5720	<p>If the value passes its range check, it is padded with as many
5721	leading zero digits as necessary to meet the padding argument.</p>
5722	<p>A TYPE_INTEGER value buffer can conveniently be interpreted with
5723	the C library function atoi(3).</p>
5724	<h1 class="BRIDGEHEAD"><a name="AEN1090" id=
5725	"AEN1090"></a>TYPE_NUMERIC</h1>
5726	<p>This field type accepts a decimal number. It is set up as
5727	follows:</p>
5728	<table border="0" bgcolor="#E0E0E0" width="100%">
5729	<tr>
5730	<td>
5731	<pre class="PROGRAMLISTING">
5732	<font color=
5733	"#000000">int set_field_type(FIELD field, / field to alter */
5734	TYPE_NUMERIC, /* type to associate */
5735	int padding, /* # places of precision */
5736	int vmin, int vmax); /* valid range */</font>
5737	</pre></td>
5738	</tr>
5739	</table>
5740	<p>Valid characters consist of an optional leading minus and
5741	digits. possibly including a decimal point. The range check is
5742	performed on exit. If the range maximum is less than or equal to
5743	the minimum, the range is ignored.</p>
5744	<p>If the value passes its range check, it is padded with as many
5745	trailing zero digits as necessary to meet the padding argument.</p>
5746	<p>A TYPE_NUMERIC value buffer can conveniently be interpreted with
5747	the C library function atof(3).</p>
5748	<h1 class="BRIDGEHEAD"><a name="AEN1096" id=
5749	"AEN1096"></a>TYPE_REGEXP</h1>
5750	<p>This field type accepts data matching a regular expression. It
5751	is set up as follows:</p>
5752	<table border="0" bgcolor="#E0E0E0" width="100%">
5753	<tr>
5754	<td>
5755	<pre class="PROGRAMLISTING">
5756	<font color=
5757	"#000000">int set_field_type(FIELD field, / field to alter */
5758	TYPE_REGEXP, /* type to associate */
5759	char regexp); / expression to match */</font>
5760	</pre></td>
5761	</tr>
5762	</table>
5763	<p>The syntax for regular expressions is that of regcomp(3). The
5764	check for regular-expression match is performed on exit.</p>
5765	</div>
5766	<div class="SECT2">
5767	<hr>
5768	<h3 class="SECT2"><a name="FORMDRIVER" id="FORMDRIVER">18.6. Form
5769	Driver: The work horse of the forms system</a></h3>
5770	<p>As in the menu system, form_driver() plays a very important role
5771	in forms system. All types of requests to forms system should be
5772	funneled through form_driver().</p>
5773	<table border="0" bgcolor="#E0E0E0" width="100%">
5774	<tr>
5775	<td>
5776	<pre class="PROGRAMLISTING">
5777	<font color=
5778	"#000000">int form_driver(FORM form, / form on which to operate */
5779	int request) /* form request code */</font>
5780	</pre></td>
5781	</tr>
5782	</table>
5783	<p>As you have seen some of the examples above, you have to be in a
5784	loop looking for user input and then decide whether it's a field
5785	data or a form request. The form requests are then passed to
5786	form_driver() to do the work.</p>
5787	<p>The requests roughly can be divided into following categories.
5788	Different requests and their usage is explained below:</p>
5789	<div class="SECT3">
5790	<hr>
5791	<h4 class="SECT3"><a name="PAGENAVREQ" id="PAGENAVREQ">18.6.1. Page
5792	Navigation Requests</a></h4>
5793	<p>These requests cause page-level moves through the form,
5794	triggering display of a new form screen. A form can be made of
5795	multiple pages. If you have a big form with lot of fields and
5796	logical sections, then you can divide the form into pages. The
5797	function set_new_page() to set a new page at the field
5798	specified.</p>
5799	<table border="0" bgcolor="#E0E0E0" width="100%">
5800	<tr>
5801	<td>
5802	<pre class="PROGRAMLISTING">
5803	<font color=
5804	"#000000">int set_new_page(FIELD field,/ Field at which page break to be set or unset */
5805	bool new_page_flag); /* should be TRUE to put a break */</font>
5806	</pre></td>
5807	</tr>
5808	</table>
5809	<p>The following requests allow you to move to different pages</p>
5810	<ul>
5811	<li>
5812	<p><em>REQ_NEXT_PAGE</em> Move to the next form page.</p>
5813	</li>
5814	<li>
5815	<p><em>REQ_PREV_PAGE</em> Move to the previous form page.</p>
5816	</li>
5817	<li>
5818	<p><em>REQ_FIRST_PAGE</em> Move to the first form page.</p>
5819	</li>
5820	<li>
5821	<p><em>REQ_LAST_PAGE</em> Move to the last form page.</p>
5822	</li>
5823	</ul>
5824	<p>These requests treat the list as cyclic; that is, REQ_NEXT_PAGE
5825	from the last page goes to the first, and REQ_PREV_PAGE from the
5826	first page goes to the last.</p>
5827	</div>
5828	<div class="SECT3">
5829	<hr>
5830	<h4 class="SECT3"><a name="INTERFIELDNAVREQ" id=
5831	"INTERFIELDNAVREQ">18.6.2. Inter-Field Navigation Requests</a></h4>
5832	<p>These requests handle navigation between fields on the same
5833	page.</p>
5834	<ul>
5835	<li>
5836	<p><em>REQ_NEXT_FIELD</em> Move to next field.</p>
5837	</li>
5838	<li>
5839	<p><em>REQ_PREV_FIELD</em> Move to previous field.</p>
5840	</li>
5841	<li>
5842	<p><em>REQ_FIRST_FIELD</em> Move to the first field.</p>
5843	</li>
5844	<li>
5845	<p><em>REQ_LAST_FIELD</em> Move to the last field.</p>
5846	</li>
5847	<li>
5848	<p><em>REQ_SNEXT_FIELD</em> Move to sorted next field.</p>
5849	</li>
5850	<li>
5851	<p><em>REQ_SPREV_FIELD</em> Move to sorted previous field.</p>
5852	</li>
5853	<li>
5854	<p><em>REQ_SFIRST_FIELD</em> Move to the sorted first field.</p>
5855	</li>
5856	<li>
5857	<p><em>REQ_SLAST_FIELD</em> Move to the sorted last field.</p>
5858	</li>
5859	<li>
5860	<p><em>REQ_LEFT_FIELD</em> Move left to field.</p>
5861	</li>
5862	<li>
5863	<p><em>REQ_RIGHT_FIELD</em> Move right to field.</p>
5864	</li>
5865	<li>
5866	<p><em>REQ_UP_FIELD</em> Move up to field.</p>
5867	</li>
5868	<li>
5869	<p><em>REQ_DOWN_FIELD</em> Move down to field.</p>
5870	</li>
5871	</ul>
5872	<p>These requests treat the list of fields on a page as cyclic;
5873	that is, REQ_NEXT_FIELD from the last field goes to the first, and
5874	REQ_PREV_FIELD from the first field goes to the last. The order of
5875	the fields for these (and the REQ_FIRST_FIELD and REQ_LAST_FIELD
5876	requests) is simply the order of the field pointers in the form
5877	array (as set up by new_form() or set_form_fields()</p>
5878	<p>It is also possible to traverse the fields as if they had been
5879	sorted in screen-position order, so the sequence goes left-to-right
5880	and top-to-bottom. To do this, use the second group of four
5881	sorted-movement requests.</p>
5882	<p>Finally, it is possible to move between fields using visual
5883	directions up, down, right, and left. To accomplish this, use the
5884	third group of four requests. Note, however, that the position of a
5885	form for purposes of these requests is its upper-left corner.</p>
5886	<p>For example, suppose you have a multi-line field B, and two
5887	single-line fields A and C on the same line with B, with A to the
5888	left of B and C to the right of B. A REQ_MOVE_RIGHT from A will go
5889	to B only if A, B, and C all share the same first line; otherwise
5890	it will skip over B to C.</p>
5891	</div>
5892	<div class="SECT3">
5893	<hr>
5894	<h4 class="SECT3"><a name="INTRAFIELDNAVREQ" id=
5895	"INTRAFIELDNAVREQ">18.6.3. Intra-Field Navigation Requests</a></h4>
5896	<p>These requests drive movement of the edit cursor within the
5897	currently selected field.</p>
5898	<ul>
5899	<li>
5900	<p><em>REQ_NEXT_CHAR</em> Move to next character.</p>
5901	</li>
5902	<li>
5903	<p><em>REQ_PREV_CHAR</em> Move to previous character.</p>
5904	</li>
5905	<li>
5906	<p><em>REQ_NEXT_LINE</em> Move to next line.</p>
5907	</li>
5908	<li>
5909	<p><em>REQ_PREV_LINE</em> Move to previous line.</p>
5910	</li>
5911	<li>
5912	<p><em>REQ_NEXT_WORD</em> Move to next word.</p>
5913	</li>
5914	<li>
5915	<p><em>REQ_PREV_WORD</em> Move to previous word.</p>
5916	</li>
5917	<li>
5918	<p><em>REQ_BEG_FIELD</em> Move to beginning of field.</p>
5919	</li>
5920	<li>
5921	<p><em>REQ_END_FIELD</em> Move to end of field.</p>
5922	</li>
5923	<li>
5924	<p><em>REQ_BEG_LINE</em> Move to beginning of line.</p>
5925	</li>
5926	<li>
5927	<p><em>REQ_END_LINE</em> Move to end of line.</p>
5928	</li>
5929	<li>
5930	<p><em>REQ_LEFT_CHAR</em> Move left in field.</p>
5931	</li>
5932	<li>
5933	<p><em>REQ_RIGHT_CHAR</em> Move right in field.</p>
5934	</li>
5935	<li>
5936	<p><em>REQ_UP_CHAR</em> Move up in field.</p>
5937	</li>
5938	<li>
5939	<p><em>REQ_DOWN_CHAR</em> Move down in field.</p>
5940	</li>
5941	</ul>
5942	<p>Each word is separated from the previous and next characters by
5943	whitespace. The commands to move to beginning and end of line or
5944	field look for the first or last non-pad character in their
5945	ranges.</p>
5946	</div>
5947	<div class="SECT3">
5948	<hr>
5949	<h4 class="SECT3"><a name="SCROLLREQ" id="SCROLLREQ">18.6.4.
5950	Scrolling Requests</a></h4>
5951	<p>Fields that are dynamic and have grown and fields explicitly
5952	created with offscreen rows are scrollable. One-line fields scroll
5953	horizontally; multi-line fields scroll vertically. Most scrolling
5954	is triggered by editing and intra-field movement (the library
5955	scrolls the field to keep the cursor visible). It is possible to
5956	explicitly request scrolling with the following requests:</p>
5957	<ul>
5958	<li>
5959	<p><em>REQ_SCR_FLINE</em> Scroll vertically forward a line.</p>
5960	</li>
5961	<li>
5962	<p><em>REQ_SCR_BLINE</em> Scroll vertically backward a line.</p>
5963	</li>
5964	<li>
5965	<p><em>REQ_SCR_FPAGE</em> Scroll vertically forward a page.</p>
5966	</li>
5967	<li>
5968	<p><em>REQ_SCR_BPAGE</em> Scroll vertically backward a page.</p>
5969	</li>
5970	<li>
5971	<p><em>REQ_SCR_FHPAGE</em> Scroll vertically forward half a
5972	page.</p>
5973	</li>
5974	<li>
5975	<p><em>REQ_SCR_BHPAGE</em> Scroll vertically backward half a
5976	page.</p>
5977	</li>
5978	<li>
5979	<p><em>REQ_SCR_FCHAR</em> Scroll horizontally forward a
5980	character.</p>
5981	</li>
5982	<li>
5983	<p><em>REQ_SCR_BCHAR</em> Scroll horizontally backward a
5984	character.</p>
5985	</li>
5986	<li>
5987	<p><em>REQ_SCR_HFLINE</em> Scroll horizontally one field width
5988	forward.</p>
5989	</li>
5990	<li>
5991	<p><em>REQ_SCR_HBLINE</em> Scroll horizontally one field width
5992	backward.</p>
5993	</li>
5994	<li>
5995	<p><em>REQ_SCR_HFHALF</em> Scroll horizontally one half field width
5996	forward.</p>
5997	</li>
5998	<li>
5999	<p><em>REQ_SCR_HBHALF</em> Scroll horizontally one half field width
6000	backward.</p>
6001	</li>
6002	</ul>
6003	<p>For scrolling purposes, a page of a field is the height of its
6004	visible part.</p>
6005	</div>
6006	<div class="SECT3">
6007	<hr>
6008	<h4 class="SECT3"><a name="EDITREQ" id="EDITREQ">18.6.5. Editing
6009	Requests</a></h4>
6010	<p>When you pass the forms driver an ASCII character, it is treated
6011	as a request to add the character to the field's data buffer.
6012	Whether this is an insertion or a replacement depends on the
6013	field's edit mode (insertion is the default.</p>
6014	<p>The following requests support editing the field and changing
6015	the edit mode:</p>
6016	<ul>
6017	<li>
6018	<p><em>REQ_INS_MODE</em> Set insertion mode.</p>
6019	</li>
6020	<li>
6021	<p><em>REQ_OVL_MODE</em> Set overlay mode.</p>
6022	</li>
6023	<li>
6024	<p><em>REQ_NEW_LINE</em> New line request (see below for
6025	explanation).</p>
6026	</li>
6027	<li>
6028	<p><em>REQ_INS_CHAR</em> Insert space at character location.</p>
6029	</li>
6030	<li>
6031	<p><em>REQ_INS_LINE</em> Insert blank line at character
6032	location.</p>
6033	</li>
6034	<li>
6035	<p><em>REQ_DEL_CHAR</em> Delete character at cursor.</p>
6036	</li>
6037	<li>
6038	<p><em>REQ_DEL_PREV</em> Delete previous word at cursor.</p>
6039	</li>
6040	<li>
6041	<p><em>REQ_DEL_LINE</em> Delete line at cursor.</p>
6042	</li>
6043	<li>
6044	<p><em>REQ_DEL_WORD</em> Delete word at cursor.</p>
6045	</li>
6046	<li>
6047	<p><em>REQ_CLR_EOL</em> Clear to end of line.</p>
6048	</li>
6049	<li>
6050	<p><em>REQ_CLR_EOF</em> Clear to end of field.</p>
6051	</li>
6052	<li>
6053	<p><em>REQ_CLR_FIELD</em> Clear entire field.</p>
6054	</li>
6055	</ul>
6056	<p>The behavior of the REQ_NEW_LINE and REQ_DEL_PREV requests is
6057	complicated and partly controlled by a pair of forms options. The
6058	special cases are triggered when the cursor is at the beginning of
6059	a field, or on the last line of the field.</p>
6060	<p>First, we consider REQ_NEW_LINE:</p>
6061	<p>The normal behavior of REQ_NEW_LINE in insert mode is to break
6062	the current line at the position of the edit cursor, inserting the
6063	portion of the current line after the cursor as a new line
6064	following the current and moving the cursor to the beginning of
6065	that new line (you may think of this as inserting a newline in the
6066	field buffer).</p>
6067	<p>The normal behavior of REQ_NEW_LINE in overlay mode is to clear
6068	the current line from the position of the edit cursor to end of
6069	line. The cursor is then moved to the beginning of the next
6070	line.</p>
6071	<p>However, REQ_NEW_LINE at the beginning of a field, or on the
6072	last line of a field, instead does a REQ_NEXT_FIELD. O_NL_OVERLOAD
6073	option is off, this special action is disabled.</p>
6074	<p>Now, let us consider REQ_DEL_PREV:</p>
6075	<p>The normal behavior of REQ_DEL_PREV is to delete the previous
6076	character. If insert mode is on, and the cursor is at the start of
6077	a line, and the text on that line will fit on the previous one, it
6078	instead appends the contents of the current line to the previous
6079	one and deletes the current line (you may think of this as deleting
6080	a newline from the field buffer).</p>
6081	<p>However, REQ_DEL_PREV at the beginning of a field is instead
6082	treated as a REQ_PREV_FIELD.</p>
6083	<p>If the O_BS_OVERLOAD option is off, this special action is
6084	disabled and the forms driver just returns E_REQUEST_DENIED.</p>
6085	</div>
6086	<div class="SECT3">
6087	<hr>
6088	<h4 class="SECT3"><a name="ORDERREQ" id="ORDERREQ">18.6.6. Order
6089	Requests</a></h4>
6090	<p>If the type of your field is ordered, and has associated
6091	functions for getting the next and previous values of the type from
6092	a given value, there are requests that can fetch that value into
6093	the field buffer:</p>
6094	<ul>
6095	<li>
6096	<p><em>REQ_NEXT_CHOICE</em> Place the successor value of the
6097	current value in the buffer.</p>
6098	</li>
6099	<li>
6100	<p><em>REQ_PREV_CHOICE</em> Place the predecessor value of the
6101	current value in the buffer.</p>
6102	</li>
6103	</ul>
6104	<p>Of the built-in field types, only TYPE_ENUM has built-in
6105	successor and predecessor functions. When you define a field type
6106	of your own (see Custom Validation Types), you can associate our
6107	own ordering functions.</p>
6108	</div>
6109	<div class="SECT3">
6110	<hr>
6111	<h4 class="SECT3"><a name="APPLICCOMMANDS" id=
6112	"APPLICCOMMANDS">18.6.7. Application Commands</a></h4>
6113	<p>Form requests are represented as integers above the curses value
6114	greater than KEY_MAX and less than or equal to the constant
6115	MAX_COMMAND. A value within this range gets ignored by
6116	form_driver(). So this can be used for any purpose by the
6117	application. It can be treated as an application specific action
6118	and take corresponding action.</p>
6119	</div>
6120	</div>
6121	</div>
6122	<div class="SECT1">
6123	<hr>
6124	<h2 class="SECT1"><a name="TOOLS" id="TOOLS">19. Tools and Widget
6125	Libraries</a></h2>
6126	<p>Now that you have seen the capabilities of ncurses and its
6127	sister libraries, you are rolling your sleeves up and gearing for a
6128	project that heavily manipulates screen. But wait.. It can be
6129	pretty difficult to write and maintain complex GUI widgets in plain
6130	ncurses or even with the additional libraries. There are some
6131	ready-to-use tools and widget libraries that can be used instead of
6132	writing your own widgets. You can use some of them, get ideas from
6133	the code, or even extend them.</p>
6134	<div class="SECT2">
6135	<hr>
6136	<h3 class="SECT2"><a name="CDK" id="CDK">19.1. CDK (Curses
6137	Development Kit)</a></h3>
6138	<p>In the author's words</p>
6139	<p><em>CDK stands for 'Curses Development Kit' and it currently
6140	contains 21 ready to use widgets which facilitate the speedy
6141	development of full screen curses programs.</em></p>
6142	<p>The kit provides some useful widgets, which can be used in your
6143	programs directly. It's pretty well written and the documentation
6144	is very good. The examples in the examples directory can be a good
6145	place to start for beginners. The CDK can be downloaded from
6146	<a href="http://invisible-island.net/cdk/" target=
6147	"_top">http://invisible-island.net/cdk/</a> . Follow the
6148	instructions in README file to install it.</p>
6149	<div class="SECT3">
6150	<hr>
6151	<h4 class="SECT3"><a name="WIDGETLIST" id="WIDGETLIST">19.1.1.
6152	Widget List</a></h4>
6153	<p>The following is the list of widgets provided with cdk and their
6154	description.</p>
6155	<table border="0" bgcolor="#E0E0E0" width="100%">
6156	<tr>
6157	<td>
6158	<pre class="PROGRAMLISTING">
6159	<font color="#000000">Widget Type Quick Description
6160	===========================================================================
6161	Alphalist Allows a user to select from a list of words, with
6162	the ability to narrow the search list by typing in a
6163	few characters of the desired word.
6164	Buttonbox This creates a multiple button widget.
6165	Calendar Creates a little simple calendar widget.
6166	Dialog Prompts the user with a message, and the user
6167	can pick an answer from the buttons provided.
6168	Entry Allows the user to enter various types of information.
6169	File Selector A file selector built from Cdk base widgets. This
6170	example shows how to create more complicated widgets
6171	using the Cdk widget library.
6172	Graph Draws a graph.
6173	Histogram Draws a histogram.
6174	Item List Creates a pop up field which allows the user to select
6175	one of several choices in a small field. Very useful
6176	for things like days of the week or month names.
6177	Label Displays messages in a pop up box, or the label can be
6178	considered part of the screen.
6179	Marquee Displays a message in a scrolling marquee.
6180	Matrix Creates a complex matrix with lots of options.
6181	Menu Creates a pull-down menu interface.
6182	Multiple Line Entry A multiple line entry field. Very useful
6183	for long fields. (like a description
6184	field)
6185	Radio List Creates a radio button list.
6186	Scale Creates a numeric scale. Used for allowing a user to
6187	pick a numeric value and restrict them to a range of
6188	values.
6189	Scrolling List Creates a scrolling list/menu list.
6190	Scrolling Window Creates a scrolling log file viewer. Can add
6191	information into the window while its running.
6192	A good widget for displaying the progress of
6193	something. (akin to a console window)
6194	Selection List Creates a multiple option selection list.
6195	Slider Akin to the scale widget, this widget provides a
6196	visual slide bar to represent the numeric value.
6197	Template Creates a entry field with character sensitive
6198	positions. Used for pre-formatted fields like
6199	dates and phone numbers.
6200	Viewer This is a file/information viewer. Very useful
6201	when you need to display loads of information.
6202	===========================================================================</font>
6203	</pre></td>
6204	</tr>
6205	</table>
6206	<p>A few of the widgets are modified by Thomas Dickey in recent
6207	versions.</p>
6208	</div>
6209	<div class="SECT3">
6210	<hr>
6211	<h4 class="SECT3"><a name="CDKATTRACT" id="CDKATTRACT">19.1.2. Some
6212	Attractive Features</a></h4>
6213	<p>Apart from making our life easier with readily usable widgets,
6214	cdk solves one frustrating problem with printing multi colored
6215	strings, justified strings elegantly. Special formatting tags can
6216	be embedded in the strings which are passed to CDK functions. For
6217	Example</p>
6218	<p>If the string</p>
6219	<table border="0" bgcolor="#E0E0E0" width="100%">
6220	<tr>
6221	<td>
6222	<pre class="PROGRAMLISTING">
6223	<font color=
6224	"#000000">"</B/1>This line should have a yellow foreground and a blue
6225	background.<!1>"</font>
6226	</pre></td>
6227	</tr>
6228	</table>
6229	<p>given as a parameter to newCDKLabel(), it prints the line with
6230	yellow foreground and blue background. There are other tags
6231	available for justifying string, embedding special drawing
6232	characters etc.. Please refer to the man page cdk_display(3X) for
6233	details. The man page explains the usage with nice examples.</p>
6234	</div>
6235	<div class="SECT3">
6236	<hr>
6237	<h4 class="SECT3"><a name="CDKCONCLUSION" id=
6238	"CDKCONCLUSION">19.1.3. Conclusion</a></h4>
6239	<p>All in all, CDK is a well-written package of widgets, which if
6240	used properly can form a strong frame work for developing complex
6241	GUI.</p>
6242	</div>
6243	</div>
6244	<div class="SECT2">
6245	<hr>
6246	<h3 class="SECT2"><a name="DIALOG" id="DIALOG">19.2. The
6247	dialog</a></h3>
6248	<p>Long long ago, in September 1994, when few people knew linux,
6249	Jeff Tranter wrote an <a href=
6250	"http://www2.linuxjournal.com/lj-issues/issue5/2807.html" target=
6251	"_top">article</a> on dialog in Linux Journal. He starts the
6252	article with these words..</p>
6253	<p><em>Linux is based on the Unix operating system, but also
6254	features a number of unique and useful kernel features and
6255	application programs that often go beyond what is available under
6256	Unix. One little-known gem is "dialog", a utility for creating
6257	professional-looking dialog boxes from within shell scripts. This
6258	article presents a tutorial introduction to the dialog utility, and
6259	shows examples of how and where it can be used</em></p>
6260	<p>As he explains, dialog is a real gem in making
6261	professional-looking dialog boxes with ease. It creates a variety
6262	of dialog boxes, menus, check lists etc.. It is usually installed
6263	by default. If not, you can download it from <a href=
6264	"http://invisible-island.net/dialog/" target="_top">Thomas
6265	Dickey</a>'s site.</p>
6266	<p>The above-mentioned article gives a very good overview of its
6267	uses and capabilites. The man page has more details. It can be used
6268	in variety of situations. One good example is building of linux
6269	kernel in text mode. Linux kernel uses a modified version of dialog
6270	tailored for its needs.</p>
6271	<p>dialog was initially designed to be used with shell scripts. If
6272	you want to use its functionality in a c program, then you can use
6273	libdialog. The documentation regarding this is sparse. Definitive
6274	reference is the dialog.h header file which comes with the library.
6275	You may need to hack here and there to get the required output. The
6276	source is easily customizable. I have used it on a number of
6277	occasions by modifying the code.</p>
6278	</div>
6279	<div class="SECT2">
6280	<hr>
6281	<h3 class="SECT2"><a name="PERLCURSES" id="PERLCURSES">19.3. Perl
6282	Curses Modules CURSES::FORM and CURSES::WIDGETS</a></h3>
6283	<p>The perl module Curses, Curses::Form and Curses::Widgets give
6284	access to curses from perl. If you have curses and basic perl is
6285	installed, you can get these modules from <a href=
6286	"http://www.cpan.org/modules/01modules.index.html" target=
6287	"_top">CPAN All Modules page</a>. Get the three zipped modules in
6288	the Curses category. Once installed you can use these modules from
6289	perl scripts like any other module. For more information on perl
6290	modules see perlmod man page. The above modules come with good
6291	documentation and they have some demo scripts to test the
6292	functionality. Though the widgets provided are very rudimentary,
6293	these modules provide good access to curses library from perl.</p>
6294	<p>Some of my code examples are converted to perl by Anuradha
6295	Ratnaweera and they are available in the <var class=
6296	"LITERAL">perl</var> directory.</p>
6297	<p>For more information see man pages Curses(3) , Curses::Form(3)
6298	and Curses::Widgets(3). These pages are installed only when the
6299	above modules are acquired and installed.</p>
6300	</div>
6301	</div>
6302	<div class="SECT1">
6303	<hr>
6304	<h2 class="SECT1"><a name="JUSTFORFUN" id="JUSTFORFUN">20. Just For
6305	Fun !!!</a></h2>
6306	<p>This section contains few programs written by me just for fun.
6307	They don't signify a better programming practice or the best way of
6308	using ncurses. They are provided here so as to allow beginners to
6309	get ideas and add more programs to this section. If you have
6310	written a couple of nice, simple programs in curses and want them
6311	to included here, contact <a href="mailto:ppadala@gmail.com"
6312	target="_top">me</a>.</p>
6313	<div class="SECT2">
6314	<hr>
6315	<h3 class="SECT2"><a name="GAMEOFLIFE" id="GAMEOFLIFE">20.1. The
6316	Game of Life</a></h3>
6317	<p>Game of life is a wonder of math. In <a href=
6318	"http://www.math.com/students/wonders/life/life.html" target=
6319	"_top">Paul Callahan</a>'s words</p>
6320	<table border="0" bgcolor="#E0E0E0" width="100%">
6321	<tr>
6322	<td>
6323	<pre class="PROGRAMLISTING">
6324	<font color=
6325	"#000000"><em>The Game of Life (or simply Life) is not a game in the conventional sense. There
6326	are no players, and no winning or losing. Once the "pieces" are placed in the
6327	starting position, the rules determine everything that happens later.
6328	Nevertheless, Life is full of surprises! In most cases, it is impossible to look
6329	at a starting position (or pattern) and see what will happen in the future. The
6330	only way to find out is to follow the rules of the game.</em></font>
6331	</pre></td>
6332	</tr>
6333	</table>
6334	<p>This program starts with a simple inverted U pattern and shows
6335	how wonderful life works. There is a lot of room for improvement in
6336	the program. You can let the user enter pattern of his choice or
6337	even take input from a file. You can also change rules and play
6338	with a lot of variations. Search on <a href="http://www.google.com"
6339	target="_top">google</a> for interesting information on game of
6340	life.</p>
6341	<p><em>File Path: JustForFun/life.c</em></p>
6342	</div>
6343	<div class="SECT2">
6344	<hr>
6345	<h3 class="SECT2"><a name="MAGIC" id="MAGIC">20.2. Magic
6346	Square</a></h3>
6347	<p>Magic Square, another wonder of math, is very simple to
6348	understand but very difficult to make. In a magic square sum of the
6349	numbers in each row, each column is equal. Even diagnol sum can be
6350	equal. There are many variations which have special properties.</p>
6351	<p>This program creates a simple magic square of odd order.</p>
6352	<p><em>File Path: JustForFun/magic.c</em></p>
6353	</div>
6354	<div class="SECT2">
6355	<hr>
6356	<h3 class="SECT2"><a name="HANOI" id="HANOI">20.3. Towers of
6357	Hanoi</a></h3>
6358	<p>The famous towers of hanoi solver. The aim of the game is to
6359	move the disks on the first peg to last peg, using middle peg as a
6360	temporary stay. The catch is not to place a larger disk over a
6361	small disk at any time.</p>
6362	<p><em>File Path: JustForFun/hanoi.c</em></p>
6363	</div>
6364	<div class="SECT2">
6365	<hr>
6366	<h3 class="SECT2"><a name="QUEENS" id="QUEENS">20.4. Queens
6367	Puzzle</a></h3>
6368	<p>The objective of the famous N-Queen puzzle is to put N queens on
6369	a N X N chess board without attacking each other.</p>
6370	<p>This program solves it with a simple backtracking technique.</p>
6371	<p><em>File Path: JustForFun/queens.c</em></p>
6372	</div>
6373	<div class="SECT2">
6374	<hr>
6375	<h3 class="SECT2"><a name="SHUFFLE" id="SHUFFLE">20.5.
6376	Shuffle</a></h3>
6377	<p>A fun game, if you have time to kill.</p>
6378	<p><em>File Path: JustForFun/shuffle.c</em></p>
6379	</div>
6380	<div class="SECT2">
6381	<hr>
6382	<h3 class="SECT2"><a name="TT" id="TT">20.6. Typing Tutor</a></h3>
6383	<p>A simple typing tutor, I created more out of need than for ease
6384	of use. If you know how to put your fingers correctly on the
6385	keyboard, but lack practice, this can be helpful.</p>
6386	<p><em>File Path: JustForFun/tt.c</em></p>
6387	</div>
6388	</div>
6389	<div class="SECT1">
6390	<hr>
6391	<h2 class="SECT1"><a name="REF" id="REF">21. References</a></h2>
6392	<ul>
6393	<li>
6394	<p>NCURSES man pages</p>
6395	</li>
6396	<li>
6397	<p>NCURSES FAQ at <a href=
6398	"http://invisible-island.net/ncurses/ncurses.faq.html" target=
6399	"_top">http://invisible-island.net/ncurses/ncurses.faq.html</a></p>
6400	</li>
6401	<li>
6402	<p>Writing programs with NCURSES by Eric Raymond and Zeyd M.
6403	Ben-Halim at <a href=
6404	"http://invisible-island.net/ncurses/ncurses-intro.html" target=
6405	"_top">http://invisible-island.net/ncurses/ncurses-intro.html</a> -
6406	somewhat obsolete. I was inspired by this document and the
6407	structure of this HOWTO follows from the original document</p>
6408	</li>
6409	</ul>
6410	</div>
6411	</div>
6412	</body>
6413	</html>

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