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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><!-- /home/reggie/tmp/qt-3.0-reggie-5401/qt-x11-commercial-3.0.5/examples/forever/forever.doc:5 --><html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>A Rectangle Draw "Benchmark"</title><style type="text/css"><!--h3.fn,span.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>A Rectangle Draw "Benchmark"</h1> <p> This example continuously draws rectangles in a window andhas another widget that counts the number of rectangles thatare drawn per second.<p> <hr><p> Header file:<p> <pre>/****************************************************************************** $Id: qt/forever.h 3.0.5 edited Oct 12 2001 $**** Definition of something or other**** Created : 979899**** Copyright (C) 1997 by Trolltech AS. 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 3.0.5 edited Oct 12 2001 $**** Copyright (C) 1992-2000 Trolltech AS. 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="f292"></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="x800"></a> <a href="qobject.html#connect">connect</a>( counter, SIGNAL(<a href="qtimer.html#timeout">timeout</a>()), this, SLOT(updateCaption()) );<a name="x799"></a> counter-><a href="qtimer.html#start">start</a>( 1000 );}void <a name="f293"></a>Forever::updateCaption(){ <a href="qstring.html">QString</a> s;<a name="x798"></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.//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="x794"></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 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>.<!-- eof --><p><address><hr><div align=center><table width=100% cellspacing=0 border=0><tr><td>Copyright © 2002 <a href="http://www.trolltech.com">Trolltech</a><td><a href="http://www.trolltech.com/trademarks.html">Trademarks</a><td align=right><div align=right>Qt version 3.0.5</div></table></div></address></body></html>⌨️ 快捷键说明
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