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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<title>A Rectangle Draw "Benchmark"</title>
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<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>A Rectangle Draw "Benchmark"</h1>
<p>
This example continuously draws rectangles in a window and
has another widget that counts the number of rectangles that
are drawn per second.
<p> <hr>
<p> Header file:
<p> <pre>/****************************************************************************
** $Id: qt/forever.h 3.3.8 edited Jan 11 14:46 $
**
** Definition of something or other
**
** Created : 979899
**
** Copyright (C) 1997-2007 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.
**
*****************************************************************************/
#ifndef FOREVER_H
#define FOREVER_H
#include <<a href="qwidget-h.html">qwidget.h</a>>
const int numColors = 120;
class Forever : public <a href="qwidget.html">QWidget</a>
{
<a href="metaobjects.html#Q_OBJECT">Q_OBJECT</a>
public:
Forever( <a href="qwidget.html">QWidget</a> *parent=0, const char *name=0 );
protected:
void paintEvent( <a href="qpaintevent.html">QPaintEvent</a> * );
void timerEvent( <a href="qtimerevent.html">QTimerEvent</a> * );
private slots:
void updateCaption();
private:
int rectangles;
QColor colors[numColors];
};
#endif
</pre>
<p> <hr>
<p> Implementation:
<p> <pre>/****************************************************************************
** $Id: qt/forever.cpp 3.3.8 edited Jan 11 14:37 $
**
** Copyright (C) 1992-2007 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 <<a href="qtimer-h.html">qtimer.h</a>>
#include <<a href="qpainter-h.html">qpainter.h</a>>
#include <<a href="qapplication-h.html">qapplication.h</a>>
#include <stdlib.h> // defines rand() function
#include "forever.h"
//
// Forever - a widget that draws rectangles forever.
//
//
// Constructs a Forever widget.
//
<a name="f365"></a>Forever::Forever( <a href="qwidget.html">QWidget</a> *parent, const char *name )
: <a href="qwidget.html">QWidget</a>( parent, name )
{
for (int a=0; a<numColors; a++) {
colors[a] = QColor( rand()&255,
rand()&255,
rand()&255 );
}
rectangles = 0;
<a href="qobject.html#startTimer">startTimer</a>( 0 ); // run continuous timer
<a href="qtimer.html">QTimer</a> * counter = new <a href="qtimer.html">QTimer</a>( this );
<a name="x1054"></a> <a href="qobject.html#connect">connect</a>( counter, SIGNAL(<a href="qtimer.html#timeout">timeout</a>()),
this, SLOT(updateCaption()) );
<a name="x1053"></a> counter-><a href="qtimer.html#start">start</a>( 1000 );
}
void <a name="f366"></a>Forever::updateCaption()
{
<a href="qstring.html">QString</a> s;
<a name="x1052"></a> s.<a href="qstring.html#sprintf">sprintf</a>( "Qt Example - Forever - %d rectangles/second", rectangles );
rectangles = 0;
<a href="qwidget.html#setCaption">setCaption</a>( s );
}
//
// Handles paint events for the Forever widget.
//
<a name="x1055"></a>void Forever::<a href="qwidget.html#paintEvent">paintEvent</a>( <a href="qpaintevent.html">QPaintEvent</a> * )
{
<a href="qpainter.html">QPainter</a> paint( this ); // painter object
int w = <a href="qwidget.html#width">width</a>();
int h = <a href="qwidget.html#height">height</a>();
if(w <= 0 || h <= 0)
return;
paint.<a href="qpainter.html#setPen">setPen</a>( NoPen ); // do not draw outline
paint.<a href="qpainter.html#setBrush">setBrush</a>( colors[rand() % numColors]);// set random brush color
<a href="qpoint.html">QPoint</a> p1( rand()%w, rand()%h ); // p1 = top left
<a href="qpoint.html">QPoint</a> p2( rand()%w, rand()%h ); // p2 = bottom right
<a href="qrect.html">QRect</a> r( p1, p2 );
paint.<a href="qpainter.html#drawRect">drawRect</a>( r ); // draw filled rectangle
}
//
// Handles timer events for the Forever widget.
//
<a name="x1048"></a>void Forever::<a href="qobject.html#timerEvent">timerEvent</a>( <a href="qtimerevent.html">QTimerEvent</a> * )
{
for ( int i=0; i<100; i++ ) {
<a href="qwidget.html#repaint">repaint</a>( FALSE ); // repaint, don't erase
rectangles++;
}
}
//
// Create and display Forever widget.
//
int main( int argc, char **argv )
{
<a href="qapplication.html">QApplication</a> a( argc, argv ); // create application object
Forever always; // create widget
always.<a href="qwidget.html#resize">resize</a>( 400, 250 ); // start up with size 400x250
a.<a href="qapplication.html#setMainWidget">setMainWidget</a>( &always ); // set as main widget
always.<a href="qwidget.html#setCaption">setCaption</a>("Qt Example - Forever");
always.<a href="qwidget.html#show">show</a>(); // show widget
return a.<a href="qapplication.html#exec">exec</a>(); // run event loop
}
</pre>
<p>See also <a href="examples.html">Examples</a>.
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