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| author | Timothy Pearson <kb9vqf@pearsoncomputing.net> | 2011-07-10 15:24:15 -0500 |
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| committer | Timothy Pearson <kb9vqf@pearsoncomputing.net> | 2011-07-10 15:24:15 -0500 |
| commit | bd0f3345a938b35ce6a12f6150373b0955b8dd12 (patch) | |
| tree | 7a520322212d48ebcb9fbe1087e7fca28b76185c /doc/html/emb-accel.html | |
| download | qt3-bd0f3345a938b35ce6a12f6150373b0955b8dd12.tar.gz qt3-bd0f3345a938b35ce6a12f6150373b0955b8dd12.zip | |
Add Qt3 development HEAD version
Diffstat (limited to 'doc/html/emb-accel.html')
| -rw-r--r-- | doc/html/emb-accel.html | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/doc/html/emb-accel.html b/doc/html/emb-accel.html new file mode 100644 index 0000000..20f8509 --- /dev/null +++ b/doc/html/emb-accel.html @@ -0,0 +1,121 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> +<!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/doc/accel.doc:36 --> +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> +<title>Adding an accelerated graphics driver to Qt/Embedded</title> +<style type="text/css"><!-- +fn { margin-left: 1cm; text-indent: -1cm; } +a:link { color: #004faf; text-decoration: none } +a:visited { color: #672967; text-decoration: none } +body { background: #ffffff; color: black; } +--></style> +</head> +<body> + +<table border="0" cellpadding="0" cellspacing="0" width="100%"> +<tr bgcolor="#E5E5E5"> +<td valign=center> + <a href="index.html"> +<font color="#004faf">Home</font></a> + | <a href="classes.html"> +<font color="#004faf">All Classes</font></a> + | <a href="mainclasses.html"> +<font color="#004faf">Main Classes</font></a> + | <a href="annotated.html"> +<font color="#004faf">Annotated</font></a> + | <a href="groups.html"> +<font color="#004faf">Grouped Classes</font></a> + | <a href="functions.html"> +<font color="#004faf">Functions</font></a> +</td> +<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>Adding an accelerated graphics driver to Qt/Embedded</h1> + + + +<p> Qt/Embedded has the capacity to make use of hardware accelerators. +To use a hardware accelerator for a PCI or AGP driver, you must +perform the following steps: +<p> <ol type=1> +<li> +Define an accelerated descendant of QLinuxFbScreen. +<p> This should implement <tt>QVoodooScreen::connect()</tt> to map its +registers. Use <tt>qt_probe_bus</tt> to get a pointer to the PCI config +space. This is where you should check that you're being pointed to the +right device (using the PCI device/manufacturer ID information). Then +use PCI config space to locate your device's accelerator registers in +physical memory and mmap the appropriate region from <tt>/dev/mem</tt>. +There is no need to map the framebuffer, <tt>QLinuxFbScreen</tt> will do +this for you. Return <tt>FALSE</tt> if a problem occurs at any point. <tt>QVoodooScreen::initDevice()</tt> will be called only by the QWS server and +is guaranteed to be called before any drawing is done (and so is a +good place to set registers to known states). <tt>connect()</tt> will be called +by every connecting client. +<p> <li> +Define an accelerated descendant of QGfxRaster. +<p> This is where the actual drawing code goes. Anything not implemented +in hardware can be passed back to <tt>QGfxRaster</tt> to do in software. Use +the optype variable to make sure that accelerated and unaccelerated +operations are synchronised (if you start drawing via software into an +area where the hardware accelerator is still drawing then your drawing +operations will appear to be in the wrong order). optype is stored in +shared memory and is set to 0 by unaccelerated operations; accelerated +operations should set it to 1. When a software graphics operation is +requested and optype is 1, <tt>QGfxRaster::sync()</tt> is called; you should +provide your own implementation of this that waits for the graphics +engine to go idle. lastop is also available for optimisation and is +stored in the shared space: this will not be set by the software-only +<tt>QGfx</tt> and can be used to store the type of your last operation (e.g. +drawing a rectangle) so that part of the setup for the next operation +can be avoided when many of the same operations are performed in +sequence. +<p> All drawing operations should be protected via a <tt>QWSDisplay::grab()</tt> +before any registers, lastop or optype are accessed, and <tt>ungrabbed()</tt> at the end. This prevents two applications trying to +access the accelerator at once and possibly locking up the machine. +It's possible that your source data is not on the graphics card so you +should check in such cases and fall back to software if necessary. +Note that <tt>QGfxRaster</tt> supports some features not directly supported +by <a href="qpainter.html">QPainter</a> (for instance, alpha channels in 32-bit data and +stretchBlt's). These features are used by Qt; stretchBlt speeds up <a href="qpixmap.html#xForm">QPixmap::xForm</a>() and <tt>drawPixmap()</tt> into a transformed <a href="qpainter.html">QPainter</a>, +alpha channel acceleration is supported for 32-bit pixmaps. +<p> <li> +If you wish, define an accelerated descendant of <tt>QScreenCursor</tt>. <tt>restoreUnder()</tt>, <tt>saveUnder()</tt>, <tt>drawCursor()</tt> and <tt>draw()</tt> should +be defined as null operations. Implement <tt>set()</tt>, <tt>move()</tt>, <tt>show()</tt> and <tt>hide()</tt>. 4KB is left for your cursor at the end of the +visible part of the framebuffer (i.e. at (width*height*depth)/8 ) +<p> <li> +Implement <tt>initCursor()</tt> and <tt>createGfx()</tt> in your <a href="qscreen.html">QScreen</a> +descendant. Implement <tt>useOffscreen()</tt> and return <tt>TRUE</tt> if you can +make use of offscreen graphics memory. +<p> <li> +Implement a small function <tt>qt_get_screen_mychip()</tt>, which simply +returns a new <tt>QMychipScreen</tt> +<p> <li> +Add your driver to the DriverTable table in <tt>qgfxraster_qws.cpp</tt>, +e.g. +<pre> +{ "MyChip", qt_get_screen_mychip,1 }, +</pre> + +<p> The first parameter is the name used with QWS_DISPLAY to request your +accelerated driver. +<p> <li> +To run with your new driver, +<pre> +export QWS_DISPLAY=MyChip +</pre> + +(optionally MyChip:/dev/fb<n> to request a different Linux +framebuffer than <tt>/dev/fb0</tt>), then run the program +<p> </ol> +<p> If your driver is not PCI or AGP you'll need to inherit <a href="qscreen.html">QScreen</a> +instead of <tt>QLinuxFbScreen</tt> and implement similar functionality to <tt>QLinuxFbScreen</tt>, but otherwise the process should be similar. The most +complete example driver is <tt>qgfxmach64_qws.cpp</tt>; <tt>qgfxvoodoo_qws.cpp</tt> may provide a smaller and easier-to-understand +driver. +<p> +<!-- eof --> +<p><address><hr><div align=center> +<table width=100% cellspacing=0 border=0><tr> +<td>Copyright © 2007 +<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a> +<td align=right><div align=right>Qt 3.3.8</div> +</table></div></address></body> +</html> |