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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Qt Toolkit - forever/forever.cpp example file</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: white; color: black; }--></style></head><body bgcolor="#ffffff"><table width="100%"><tr><td><a href="index.html"><img width="100" height="100" src="qtlogo.png"alt="Home" border="0"><img width="100"height="100" src="face.png" alt="Home" border="0"></a><td valign="top"><div align="right"><img src="dochead.png" width="472" height="27"><br><a href="classes.html"><b>Classes</b></a>- <a href="annotated.html">Annotated</a>- <a href="hierarchy.html">Tree</a>- <a href="functions.html">Functions</a>- <a href="index.html">Home</a>- <a href="topicals.html"><b>Structure</b> <font face="Arial,Helvetica,Geneva,Swiss,SunSans-Regular" align="center" size=32>Qte</font></a></div></table><h1 align=center>A Rectangle Draw "Benchmark"</h1><br clear="all"> This example continuously draws rectangles in a window and has another widget that counts the number of rectangles that are drawn per second. <hr> Header file: <pre>/****************************************************************************** $Id: qt/examples/forever/forever.h 2.3.8 edited 2004-05-12 $**** 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 QWidget{ Q_OBJECTpublic: Forever( <a href="qwidget.html">QWidget</a> *parent=0, const char *name=0 );protected: void timerEvent( <a href="qtimerevent.html">QTimerEvent</a> * );private slots: void updateCaption();private: int rectangles; <a href="qcolor.html">QColor</a> colors[numColors];};#endif</pre> <hr> Implementation:<pre>/****************************************************************************** $Id: qt/examples/forever/forever.cpp 2.3.8 edited 2004-05-12 $**** 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 name="qtimer.h"></a><a href="qtimer-h.html">qtimer.h</a>>#include <<a name="qpainter.h"></a><a href="qpainter-h.html">qpainter.h</a>>#include <<a name="qapplication.h"></a><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.//Forever::Forever( <a name="QWidget"></a><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 name="startTimer"></a><a href="qobject.html#4c6b67">startTimer</a>( 0 ); // run continuous timer <a name="QTimer"></a><a href="qtimer.html">QTimer</a> * counter = new <a href="qtimer.html">QTimer</a>( this ); <a name="connect"></a><a href="qobject.html#fbde73">connect</a>( counter, SIGNAL(timeout()), this, SLOT(<a name="updateCaption"></a><a href="#231">updateCaption</a>()) ); counter-><a name="start"></a><a href="qtimer.html#ce33bc">start</a>( 1000 );}void <a name="231"></a>Forever::updateCaption(){ <a name="QString"></a><a href="qstring.html">QString</a> s; s.<a name="sprintf"></a><a href="qstring.html#926f67">sprintf</a>( "Qt Example - Forever - %d rectangles/second", rectangles ); rectangles = 0; <a name="setCaption"></a><a href="qwidget.html#d6a291">setCaption</a>( s );}//// Handles timer events for the Forever widget.//void <a name="232"></a>Forever::timerEvent( <a name="QTimerEvent"></a><a href="qtimerevent.html">QTimerEvent</a> * ){ <a name="QPainter"></a><a href="qpainter.html">QPainter</a> paint( this ); // painter object paint.<a name="setPen"></a><a href="qpainter.html#0183e4">setPen</a>( NoPen ); // do not draw outline int w = width(); int h = height(); if( w <= 0 || h <= 0 ) return; for ( int i=0; i<100; i++ ) { paint.<a name="setBrush"></a><a href="qpainter.html#3e0cc8">setBrush</a>( colors[i % numColors]); // set random brush color <a name="QPoint"></a><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 name="QRect"></a><a href="qrect.html">QRect</a> r( p1, p2 ); paint.<a name="drawRect"></a><a href="qpainter.html#4c0077">drawRect</a>( r ); // draw filled rectangle rectangles++; }}//// Create and display Forever widget.//int main( int argc, char **argv ){ <a name="QApplication"></a><a href="qapplication.html">QApplication</a> a( argc, argv ); // create application object Forever always; // create widget a.<a name="setMainWidget"></a><a href="qapplication.html#7ad759">setMainWidget</a>( &always ); // set as main widget always.<a href="qwidget.html#d6a291">setCaption</a>("Qt Example - Forever"); always.<a name="show"></a><a href="qwidget.html#200ee5">show</a>(); // show widget return a.<a name="exec"></a><a href="qapplication.html#84c7bf">exec</a>(); // run event loop}</pre><p><address><hr><div align="center"><table width="100%" cellspacing="0" border="0"><tr><td>Copyright ⌨️ 快捷键说明
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