| [190] | 1 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
|
|---|
| 2 | <!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/doc/qvfb.doc:36 -->
|
|---|
| 3 | <html>
|
|---|
| 4 | <head>
|
|---|
| 5 | <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
|---|
| 6 | <title>Qt/Embedded Virtual Framebuffer</title>
|
|---|
| 7 | <style type="text/css"><!--
|
|---|
| 8 | fn { margin-left: 1cm; text-indent: -1cm; }
|
|---|
| 9 | a:link { color: #004faf; text-decoration: none }
|
|---|
| 10 | a:visited { color: #672967; text-decoration: none }
|
|---|
| 11 | body { background: #ffffff; color: black; }
|
|---|
| 12 | --></style>
|
|---|
| 13 | </head>
|
|---|
| 14 | <body>
|
|---|
| 15 |
|
|---|
| 16 | <table border="0" cellpadding="0" cellspacing="0" width="100%">
|
|---|
| 17 | <tr bgcolor="#E5E5E5">
|
|---|
| 18 | <td valign=center>
|
|---|
| 19 | <a href="index.html">
|
|---|
| 20 | <font color="#004faf">Home</font></a>
|
|---|
| 21 | | <a href="classes.html">
|
|---|
| 22 | <font color="#004faf">All Classes</font></a>
|
|---|
| 23 | | <a href="mainclasses.html">
|
|---|
| 24 | <font color="#004faf">Main Classes</font></a>
|
|---|
| 25 | | <a href="annotated.html">
|
|---|
| 26 | <font color="#004faf">Annotated</font></a>
|
|---|
| 27 | | <a href="groups.html">
|
|---|
| 28 | <font color="#004faf">Grouped Classes</font></a>
|
|---|
| 29 | | <a href="functions.html">
|
|---|
| 30 | <font color="#004faf">Functions</font></a>
|
|---|
| 31 | </td>
|
|---|
| 32 | <td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>Qt/Embedded Virtual Framebuffer</h1>
|
|---|
| 33 |
|
|---|
| 34 |
|
|---|
| 35 | <p> The virtual framebuffer allows Qt/Embedded programs to be developed on
|
|---|
| 36 | a desktop machine, without switching between consoles and X11.
|
|---|
| 37 | <p> The virtual framebuffer is located in <tt>$QTDIR/tools/qvfb</tt>.
|
|---|
| 38 | <p> <h2> Using the Virtual Framebuffer
|
|---|
| 39 | </h2>
|
|---|
| 40 | <a name="1"></a><p> <ol type=1>
|
|---|
| 41 | <li> Configure Qt/Embedded with the <tt>-qvfb</tt> argument and compile the library:
|
|---|
| 42 | <pre>
|
|---|
| 43 | ./configure -qvfb
|
|---|
| 44 | make
|
|---|
| 45 | </pre>
|
|---|
| 46 |
|
|---|
| 47 | <li> Compile <tt>qvfb</tt> as a normal Qt/X11 application and run it. Do <em>not</em>
|
|---|
| 48 | compile it as a Qt/Embedded application.
|
|---|
| 49 | <li> Start a Qt/Embedded master application (i.e., construct
|
|---|
| 50 | <a href="qapplication.html">QApplication</a> with the QApplication::GuiServer flag or use the <tt>-qws</tt> command line parameter). You can specify to the server that
|
|---|
| 51 | you wish to use the virtual framebuffer driver, e.g.:
|
|---|
| 52 | <pre>
|
|---|
| 53 | masterapp -qws -display QVFb:0
|
|---|
| 54 | </pre>
|
|---|
| 55 |
|
|---|
| 56 | <li> Qt/Embedded will autodetect qvfb, so you can omit the <tt>-display</tt>
|
|---|
| 57 | command line parameter if you know that qvfb is running, and that
|
|---|
| 58 | the Qt/Embedded library supports qvfb. (If this is not the case,
|
|---|
| 59 | Qt/Embedded will write to the real framebuffer, and your X11
|
|---|
| 60 | display will be corrupted.)
|
|---|
| 61 | <p> </ol>
|
|---|
| 62 | <p> <tt>qvfb</tt> supports the following command line options:
|
|---|
| 63 | <p> <center><table cellpadding="4" cellspacing="2" border="0">
|
|---|
| 64 | <tr bgcolor="#a2c511"> <th valign="top">Option <th valign="top">Meaning
|
|---|
| 65 | <tr bgcolor="#f0f0f0">
|
|---|
| 66 | <td valign="top"><tt>-width</tt> <em>width</em>
|
|---|
| 67 | <td valign="top">the width of the virtual framebuffer (default: 240).
|
|---|
| 68 | <tr bgcolor="#d0d0d0">
|
|---|
| 69 | <td valign="top"><tt>-height</tt> <em>height</em>
|
|---|
| 70 | <td valign="top">the height of the virtual framebuffer (default: 320).
|
|---|
| 71 | <tr bgcolor="#f0f0f0">
|
|---|
| 72 | <td valign="top"><tt>-depth</tt> <em>depth</em>
|
|---|
| 73 | <td valign="top">the depth of the virtual framebuffer (1, 8 or 32; default: 8).
|
|---|
| 74 | <tr bgcolor="#d0d0d0">
|
|---|
| 75 | <td valign="top"><tt>-nocursor</tt>
|
|---|
| 76 | <td valign="top">do not display the X11 cursor in the framebuffer window.
|
|---|
| 77 | <tr bgcolor="#f0f0f0">
|
|---|
| 78 | <td valign="top"><tt>-qwsdisplay</tt> <em>:id</em>
|
|---|
| 79 | <td valign="top">the Qt/Embedded display id to provide (default: :0).
|
|---|
| 80 | </table></center>
|
|---|
| 81 | <p> <h2> Virtual Framebuffer Design
|
|---|
| 82 | </h2>
|
|---|
| 83 | <a name="2"></a><p> The virtual framebuffer emulates a framebuffer using a shared memory region
|
|---|
| 84 | (the virtual frame buffer) and a utility to display the framebuffer in a
|
|---|
| 85 | window (<tt>qvfb</tt>). The regions of the display that have changed are updated
|
|---|
| 86 | periodically, so you will see discrete snapshots of the framebuffer rather
|
|---|
| 87 | than each individual drawing operation. For this reason drawing problems
|
|---|
| 88 | such as flickering may not be apparent until the program is run using a real
|
|---|
| 89 | framebuffer.
|
|---|
| 90 | <p> The target refresh rate can be set via the <b>View|Refresh Rate</b>
|
|---|
| 91 | menu item. This will cause <tt>qvfb</tt> to check for updated regions more
|
|---|
| 92 | frequently. The rate is a target only. If little drawing is being
|
|---|
| 93 | done, the framebuffer will not show any updates between drawing
|
|---|
| 94 | events. If an application is displaying an animation the updates will
|
|---|
| 95 | be frequent, then the application and <tt>qvfb</tt> will compete for
|
|---|
| 96 | processor time.
|
|---|
| 97 | <p> Mouse and keyboard events are passed to the Qt/Embedded master process via
|
|---|
| 98 | named pipes.
|
|---|
| 99 | <p> The virtual framebuffer is a development tool only. No security issues have
|
|---|
| 100 | been considered in the virtual framebuffer design. It should be avoided
|
|---|
| 101 | in a production environment; do not configure production libraries with <tt>-qvfb</tt>.
|
|---|
| 102 | <p>
|
|---|
| 103 | <!-- eof -->
|
|---|
| 104 | <p><address><hr><div align=center>
|
|---|
| 105 | <table width=100% cellspacing=0 border=0><tr>
|
|---|
| 106 | <td>Copyright © 2007
|
|---|
| 107 | <a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
|
|---|
| 108 | <td align=right><div align=right>Qt 3.3.8</div>
|
|---|
| 109 | </table></div></address></body>
|
|---|
| 110 | </html>
|
|---|
