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/****************************************************************************
**
** Example application showing how to use Qt and Qt OpenGL Extension on an
** X11 overlay visual
**
** Copyright (C) 1999-2008 Trolltech ASA. All rights reserved.
**
** This file is part of an example program for Qt. This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/
#include <qapplication.h>
#include "gearwidget.h"
#include "rubberbandwidget.h"
#if defined(Q_WS_X11)
#include <X11/Xlib.h>
#endif
QColor findOverlayTransparentColor()
{
QColor invalidColor;
#if defined(Q_WS_X11)
Display* appDisplay;
Visual* appVisual;
// The static methods are called 'App' in Qt 2.x
#if QT_VERSION < 200
appDisplay = QPaintDevice::x__Display();
appVisual = (Visual*)QPaintDevice::x11Visual();
#else
appDisplay = QPaintDevice::x11AppDisplay();
appVisual = (Visual*)QPaintDevice::x11AppVisual();
#endif
qDebug( "Default Visual ID: 0x%x", (int)XVisualIDFromVisual(appVisual) );
typedef struct OverlayProp {
long visual;
long type;
long value;
long layer;
} OverlayProp;
QWidget* rootWin = QApplication::desktop();
if ( !rootWin )
return invalidColor; // Should not happen
Atom overlayVisualsAtom = XInternAtom( appDisplay,
"SERVER_OVERLAY_VISUALS", True );
if ( overlayVisualsAtom == None ) {
warning( "Server has no overlay visuals" );
return invalidColor;
}
Atom actualType;
int actualFormat;
ulong nItems;
ulong bytesAfter;
OverlayProp* overlayProp;
int res = XGetWindowProperty( appDisplay, QApplication::desktop()->winId(),
overlayVisualsAtom, 0, 10000, False,
overlayVisualsAtom, &actualType,
&actualFormat, &nItems, &bytesAfter,
(uchar**)&overlayProp );
if ( res != Success || actualType != overlayVisualsAtom
|| actualFormat != 32 || nItems < 4 ) {
warning( "Failed to get overlay visual property from server" );
return invalidColor;
}
for ( uint i = 0; i < nItems/4; i++ ) {
if ( (VisualID)overlayProp[i].visual == XVisualIDFromVisual(appVisual)
&& overlayProp[i].type == 1 )
return QColor( qRgb( 1, 2, 3 ), overlayProp[i].value );
}
qWarning( "Default visual is not in overlay plane" );
return invalidColor;
#else // defined(Q_WS_X11)
qWarning( "Wrong window system - Only X11 has overlay support." );
return invalidColor;
#endif
}
int main( int argc, char **argv )
{
QApplication::setColorSpec( QApplication::CustomColor );
QApplication a( argc, argv );
if ( !QGLFormat::hasOpenGL() ) {
qWarning( "This system has no OpenGL support. Exiting." );
return -1;
}
QColor transparentColor = findOverlayTransparentColor();
if ( !transparentColor.isValid() ) {
qWarning( "Failed to get transparent color for overlay. Exiting." );
return -1;
}
QWidget top;
a.setMainWidget( &top );
top.setGeometry( 50, 50, 600, 400 );
// Make an OpenGL widget. It will use the deepest visual available
// (typically a TrueColor visual), which typically is in the normal layer.
GearWidget g( &top );
g.setGeometry( 20, 20, 560, 360 );
// Put the rubberband widget (which uses the default, i.e. overlay visual)
// on top of the OpenGL widget:
RubberbandWidget r( transparentColor, &top );
r.setGeometry( 20, 20, 560, 360 );
top.show();
return a.exec();
}
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