|
|
|
|
<!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/examples/opengl/overlay_x11/overlay_x11.doc:1 -->
|
|
|
|
|
<html>
|
|
|
|
|
<head>
|
|
|
|
|
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
|
|
|
|
<title>OpenGL Overlay X11 Example</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>OpenGL Overlay X11 Example</h1>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<p>
|
|
|
|
|
<b>Warning:</b> From version 5.0 onwards, the TQt OpenGL Extension includes
|
|
|
|
|
direct support for use of OpenGL overlays. For many uses of overlays,
|
|
|
|
|
this makes the technique described below redundant. See the <a href="opengl-overlay-example.html">overlay</a> example program. The
|
|
|
|
|
following is a discussion on how to use non-TQGL widgets in overlay
|
|
|
|
|
planes.
|
|
|
|
|
<p> Overlayrubber: An example program showing how to use TQt and TQt OpenGL
|
|
|
|
|
Extension with X11 overlay visuals.
|
|
|
|
|
<p> See <tt>$TQTDIR/examples/opengl/overlay_x11</tt> for the source code.
|
|
|
|
|
<p> Background information for this example can be found in the
|
|
|
|
|
information on <a href="opengl-x11-overlays.html">overlays</a>.
|
|
|
|
|
<p> The example program has three main parts:
|
|
|
|
|
<p> <ol type=1>
|
|
|
|
|
<li> <em>GearWidget</em> - a normal, simple <a href="tqglwidget.html">TQGLWidget</a>. This renders the usual
|
|
|
|
|
gears. It has been modified to print a debug message every time it
|
|
|
|
|
redraws (renders) itself. Thus, you can easily confirm that drawing in
|
|
|
|
|
the overlay plane does not cause redrawings in the main plane where
|
|
|
|
|
the TQGLWidget resides.
|
|
|
|
|
<p> <li> <em>RubberbandWidget</em> - Very simple standard (non-GL) TQt widget that
|
|
|
|
|
implements rubberband drawing. Designed for use in an overlay plane.
|
|
|
|
|
It takes the plane's transparent color as a constructor argument and
|
|
|
|
|
uses that for its background color. Thus, the widget itself will be
|
|
|
|
|
invisible, only the rubberbands it draws will be visible.
|
|
|
|
|
<p> <li> <em>main.cpp</em> Creates a GearWidget and a Rubberbandwidget and puts the
|
|
|
|
|
latter on top of the former. Contains a routine that checks that the
|
|
|
|
|
default visual is in an overlay plane, and returns the transparent
|
|
|
|
|
color of that plane.
|
|
|
|
|
</ol>
|
|
|
|
|
<p> <h2> Running the Example
|
|
|
|
|
</h2>
|
|
|
|
|
<a name="1"></a><p> Start the <tt>overlayrubber</tt> executable. Click and drag with the left
|
|
|
|
|
mouse button to see rubberband drawing. Observe that the <a href="tqglwidget.html">TQGLWidget</a>
|
|
|
|
|
does not redraw itself (no redraw debug messages are output), and yet
|
|
|
|
|
the image is not destroyed. Marvel at the coolness of X11 overlays!
|
|
|
|
|
<p> <h2> Using this technique in a real application
|
|
|
|
|
</h2>
|
|
|
|
|
<a name="2"></a><p> For clarity, this example program has been kept very simple. Here are
|
|
|
|
|
some hints for real application usage:
|
|
|
|
|
<p> <ul>
|
|
|
|
|
<p> <li> <em>All normal widgets are in the overlay plane.</em> This means that you
|
|
|
|
|
can put all kinds of TQt widgets (your own or standard TQt widgets) on
|
|
|
|
|
top of the OpenGL image (widget), e.g. pushbuttons etc., and they can
|
|
|
|
|
be moved, resized, or removed without destroying the OpenGL image.
|
|
|
|
|
<p> <li> <em>Using with geometry management.</em> The <a href="ntqlayout.html">TQLayout</a> classes don't permit
|
|
|
|
|
putting one widget (the overlay) on top of another (the OpenGL
|
|
|
|
|
widget); that would defy the whole purpose of the automatic layout.
|
|
|
|
|
The solution is to add just one of them to the TQLayout object. Have it
|
|
|
|
|
keep a pointer to the other (i.e. the <a href="tqglwidget.html">TQGLWidget</a> knows about its
|
|
|
|
|
overlay widget or vice versa). Implement the resizeEvent() method of
|
|
|
|
|
the widget you put in the layout, and make it call setGeometry() on
|
|
|
|
|
the other widget with its own geometry as parameters, thus keeping the
|
|
|
|
|
two widgets' geometries synchronized.
|
|
|
|
|
<p> <li> <em>Using together with <a href="tqpalette.html">TQPalette</a> and <a href="tqcolorgroup.html">TQColorGroup</a>.</em> Instead of the
|
|
|
|
|
simplistic setBackgroundColor( transparentColor ), you can
|
|
|
|
|
use TQt's TQPalette system to make your overlay widgets use
|
|
|
|
|
transparent color for what you want. This way, the normal TQt widgets
|
|
|
|
|
can be used as overlays for fancy effects. Just create a palette for
|
|
|
|
|
them with the transparent color for the relevant color roles, e.g.
|
|
|
|
|
Background and Base, in the Normal and/or Active modes. This way, you
|
|
|
|
|
can create see-through TQPushButtons etc.
|
|
|
|
|
</ul>
|
|
|
|
|
<p> <p>See also <a href="opengl-examples.html">OpenGL Examples</a>.
|
|
|
|
|
|
|
|
|
|
<!-- 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>TQt 3.3.8</div>
|
|
|
|
|
</table></div></address></body>
|
|
|
|
|
</html>
|
