source: trunk/doc/swt004.html@ 90

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1<?xml version='1.0' encoding='UTF-8'?>
2<?xml-stylesheet type="text/css"
3href="eclipseos2-xxe.css"
4?>
5<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
6"xhtml1-strict.dtd">
7<html>
8 <head>
9 <link type="text/css"
10 href="eclipseos2.css"
11 rel="stylesheet" />
12
13 <title>Eclipse for OS/2 Transitional Project Notes</title>
14 </head>
15
16 <body>
17 <h1>SWT Step 4. Layout basics</h1>
18
19 <h2>Objective</h2>
20
21 <p>Implement the basics of the layout management. The testcase example
22 shoud be able to create a top shell containing a simple button.</p>
23
24 <h2>Task notes</h2>
25
26 <h3>Default Shell size and position</h3>
27
28 <p>In SWT, it&#39;s assumed that the <code>o.e.swt.widgets.Shell</code> is
29 created with the default size and position assigned by the system.</p>
30
31 <p>Since OS/2 handles the <code>FS_SHELLPOSITION</code> flag in a very
32 strange manner (the size/position of the frame after creation remains zero
33 until the frame is shown for the first time, and there&#39;s no way
34 neither to get the size/position the system is going to assign nor to
35 change them before the frame is shown) the workaround is made using
36 <code>WinQueryTaskSizePos()</code> (it seems to return the same values the
37 system uses when <code>FS_SHELLPOSITION</code> is specified). This means,
38 that the <code>Shell.getBounds()</code> method will return system assigned
39 values (but not zero as it would be in the case of <code>FS_SHELLPOSITION</code>)
40 after <code>Shell</code> creation and before opening (showing) it and
41 it&#39;s also possible to change them -- the same behavior is shown in
42 Windows.</p>
43
44 <h3>Notification messages</h3>
45
46 <p>In OS/2 control notification messages (<code>WM_CONTROL</code>,
47 <code>WM_COMMAND</code>) do not necessarily contain the control window
48 handle in their parameters, only the identity is guaranteed to present in
49 most cases. Therefore, in order to send the message back to the widget
50 (this is an SWT logic and it is quite handy) the only way to determine its
51 handle, which we need to obtain a reference to the widget, is to use its
52 window ID. This, in turn, requires an algorithm to generate IDs during
53 window creation, that are unique within the owner window context. The
54 window handle could be such unique identifier, but the problem is that the
55 window ID is a 16-bit value. However, at the present, we still use it for
56 that purpose taking its low 16 bits, which is based on the assumption that
57 handles in OS/2 always have a form of <code>0x8000nnnn</code>. But this
58 assumtion is possibly erroneous, so in the future this algorithm should be
59 replaced with another one.</p>
60
61 <h3><a name="WidgetHeight">Widget height</a></h3>
62
63 <p>As mentioned in task notes of the <a
64 href="swt002.html#ScreenCoordinates">SWT002</a> step about screen
65 coordinates, we need an easy way to obtain the height of a widget as well
66 as the height of its parent to do necessary calculations related to the
67 coordinate space flipping. The package method <code>Control.getHeight()</code>
68 can still be used to get the height of the widget itself (respecting the
69 situation when the widget is the <code>Decorations</code> instance and it
70 is minimized). The height of the widget&#39;s parent can be obtained by
71 the <code>Control.getParentHeight()</code> call (which, for the
72 <code>Shell</code> class, returns the value of the <code>Shell.display.getHeight()</code>
73 method, rather then <code>parent.getHeight()</code>, if the parent is
74 <code>null</code>). The situation for non-<code>Shell</code> windows when
75 the parent is <code>null</code> is inapplicable, so the exception is
76 thrown in this case. The <code>Control.getBounds(SWP)</code> package
77 method returns the height of the parent just as it returned by the
78 <code>getParentHeight()</code> method.</p>
79
80 <h2>Step checklist</h2>
81
82 <table>
83 <col width="40%" />
84
85 <col />
86
87 <col width="50%" />
88
89 <thead>
90 <tr>
91 <th>Operation</th>
92
93 <th>Status</th>
94
95 <th>Remarks</th>
96 </tr>
97 </thead>
98
99 <tr>
100 <td>Make the size and position methods of widgets to work correcty
101 (add <code>OS.SWP</code> structre, <code>OS.WinQueryTaskSizePos()</code>,
102 <code>WinQueryWindowPos()</code>); implement <code>Display.getBounds()</code></td>
103
104 <td>Done [dmik]</td>
105
106 <td>Size and position relative methods are completely rewritten: now
107 they use the package helper method <code>getBounds(SWP)</code> which
108 uses <code>WinQueryWindowPos()</code> instead of <code>WinQueryWindowRect()</code>.</td>
109 </tr>
110
111 <tr>
112 <td>Implement <code>Decorations.{get|set}{Minimized|Maximized}()</code>
113 methods</td>
114
115 <td>Done [dmik]</td>
116
117 <td></td>
118 </tr>
119
120 <tr>
121 <td>Add <code>OS.objcpy (int, SWP)</code>, <code>objcpy(SWP, int)</code>;
122 <code>WM_WINDOWPOSCHANGED</code>, <code>WM_ADJUSTWINDOWPOS</code>
123 message handling and <code>AWP_*</code> constants; implement
124 <code>SWT.Resize</code>, <code>SWT.Move</code>, <code>SWT.Iconify</code>,
125 <code>SWT.Deiconify</code> events... Activate?</td>
126
127 <td>Done [dmik]</td>
128
129 <td></td>
130 </tr>
131
132 <tr>
133 <td>Add <code>OS.WinGetSysBitmap()</code> and <code>SBMP_*</code>
134 constants, <code>GpiQueryBitmapInfoHeader()</code> and <code>BITMAPINFOHEADER2</code>
135 class, <code>GpiDeleteBitmap()</code></td>
136
137 <td>Done [dmik]</td>
138
139 <td>Currently used to detect dimensions of the check box</td>
140 </tr>
141
142 <tr>
143 <td>Add <code>OS.WinSetPresParam()</code> and <code>PP_*</code>
144 constants, implement two helper methods (<code>Control.setPres{Foreground|Background}()</code>)</td>
145
146 <td>Done [dmik]</td>
147
148 <td>Used to set the background and foreground colors of standard
149 controls drawn by the system</td>
150 </tr>
151
152 <tr>
153 <td>add <code>BS_*</code>, <code>BM_*</code>, <code>BN_*</code>,
154 <code>BDS_*</code> constants</td>
155
156 <td>Done [dmik]</td>
157
158 <td></td>
159 </tr>
160
161 <tr>
162 <td>Add <code>malloc()</code>, <code>free()</code>, <code>memcpy()</code>,
163 <code>memset()</code>; add 3 static helper methods to <code>Control</code>:
164 <code>beginDeferWindowPos()</code>, <code>endDeferWindowPos()</code>
165 and <code>deferWindowPos()</code>; add <code>OS.WinSetMultWindowPos()</code>,
166 <code>WinIsWindow()</code></td>
167
168 <td>Done [dmik]</td>
169
170 <td>We use standard C memory management functions because there&#39;s
171 no advantage to organize a heap on the Java level. Without the heap,
172 direct calls to <code>DosAllocMem()</code> to allocate small amounts
173 waste memory since they always allocate it by blocks of 4KB.<br /><br /><code>OS.WinSetMultWindowPos()</code>
174 is used to improve the performance of sizing/moving operations.</td>
175 </tr>
176
177 <tr>
178 <td>Add handlers for <code>WM_CONTROL</code>, <code>WM_COMMAND</code>
179 messages, <code>CMDSRC_*</code> constants; Add and partially implement
180 the <code>Button</code> class (basic OS/2 buttons, <code>setSelection()</code>,
181 <code>getSelection()</code>, <code>SWT.Selection</code> event)</td>
182
183 <td>Done [dmik]</td>
184
185 <td>Only OS/2 basic button styles are now implemented (excluding
186 imaged ones)</td>
187 </tr>
188
189 <tr>
190 <td>Add <code>OS.WinCalcFrameRect()</code>, Implement <code>Composite.setLayout()</code>,
191 <code>getLayout()</code>, <code>layout()</code>, <code>Control.computeSize()</code>,
192 <code>Scrollable.computeTrim()</code></td>
193
194 <td>Done [dmik]</td>
195
196 <td>Currently scrollbars are not taken into account when calculating
197 the widget&#39;s preferred size</td>
198 </tr>
199
200 <tr>
201 <td>Replace the <code>SWT004</code> testcase with <code>SWT004_01</code>
202 and <code>SWT004_02</code> ones</td>
203
204 <td>Done [dmik]</td>
205
206 <td></td>
207 </tr>
208
209 <tr>
210 <td>Make <code>Control.getBorderWidth()</code> to return values
211 applicable for individual widgets</td>
212
213 <td>Will be done on next steps</td>
214
215 <td>Now it always returns the value of <code>SV_CXBORDER</code>, which
216 is not the case for many widgets</td>
217 </tr>
218 </table>
219 </body>
220</html>
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