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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 Tutorial - t12/cannon.cpp</title></head><body bgcolor="#ffffff"><p><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><p><h1 align=center>Source code for <a href="t12.html">tutorial 12</a>: cannon.cpp</h1><br clear="all"><hr> <pre>/******************************************************************** Implementation CannonField class, Qt tutorial 12******************************************************************/#include "cannon.h"#include <<a href="qtimer-h.html">qtimer.h</a>>#include <<a href="qpainter-h.html">qpainter.h</a>>#include <<a href="qpixmap-h.html">qpixmap.h</a>>#include <<a href="qdatetime-h.html">qdatetime.h</a>>#include <math.h>#include <stdlib.h>CannonField::CannonField( <a href="qwidget.html">QWidget</a> *parent, const char *name ) : <a href="qwidget.html">QWidget</a>( parent, name ){ ang = 45; f = 0; timerCount = 0; autoShootTimer = new <a href="qtimer.html">QTimer</a>( this, "movement handler" ); <a href="qobject.html#fbde73">connect</a>( autoShootTimer, SIGNAL(timeout()), this, SLOT(<a href=#523>moveShot</a>()) ); shoot_ang = 0; shoot_f = 0; target = QPoint( 0, 0 ); <a href="qwidget.html#d7e4b9">setPalette</a>( <a href="qpalette.html">QPalette</a>( <a href="qcolor.html">QColor</a>( 250, 250, 200) ) ); <a href=#522>newTarget</a>();}void <a name="519"></a>CannonField::setAngle( int degrees ){ if ( degrees < 5 ) degrees = 5; if ( degrees > 70 ) degrees = 70; if ( ang == degrees ) return; ang = degrees; <a href="qwidget.html#7569b1">repaint</a>( cannonRect(), FALSE ); emit angleChanged( ang );}void <a name="520"></a>CannonField::setForce( int newton ){ if ( newton < 0 ) newton = 0; if ( f == newton ) return; f = newton; emit forceChanged( f );}void <a name="521"></a>CannonField::shoot(){ if ( autoShootTimer->isActive() ) return; timerCount = 0; shoot_ang = ang; shoot_f = f; autoShootTimer->start( 50 );}void <a name="522"></a>CannonField::newTarget(){ static bool first_time = TRUE; if ( first_time ) { first_time = FALSE; <a href="qtime.html">QTime</a> midnight( 0, 0, 0 ); srand( midnight.<a href="qtime.html#0b9e38">secsTo</a>(<a href="qtime.html#6091a9">QTime::currentTime</a>()) ); } <a href="qregion.html">QRegion</a> r( <a href=#530>targetRect</a>() ); target = QPoint( 200 + rand() % 190, 10 + rand() % 255 ); <a href="qwidget.html#7569b1">repaint</a>( r.<a href="qrect.html#81e8a3">unite</a>( <a href=#530>targetRect</a>() ) );}void <a name="523"></a>CannonField::moveShot(){ <a href="qregion.html">QRegion</a> r( <a href=#529>shotRect</a>() ); timerCount++; <a href="qrect.html">QRect</a> shotR = shotRect(); if ( shotR.<a href="qrect.html#5b3d2b">intersects</a>( <a href=#530>targetRect</a>() ) ) { autoShootTimer->stop(); emit hit(); } else if ( shotR.<a href="qrect.html#fccae7">x</a>() > width() || shotR.<a href="qrect.html#f448f7">y</a>() > height() ) { autoShootTimer->stop(); emit missed(); } else { r = r.<a href="qrect.html#81e8a3">unite</a>( <a href="qregion.html">QRegion</a>( shotR ) ); } <a href="qwidget.html#7569b1">repaint</a>( r );}void <a name="524"></a>CannonField::paintEvent( <a href="qpaintevent.html">QPaintEvent</a> *e ){ <a href="qrect.html">QRect</a> updateR = e-><a href="qpaintevent.html#2d6e18">rect</a>(); <a href="qpainter.html">QPainter</a> p( this ); if ( updateR.<a href="qrect.html#5b3d2b">intersects</a>( <a href=#528>cannonRect</a>() ) ) <a href=#527>paintCannon</a>( &p ); if ( autoShootTimer->isActive() && updateR.<a href="qrect.html#5b3d2b">intersects</a>( <a href=#529>shotRect</a>() ) ) <a href=#525>paintShot</a>( &p ); if ( updateR.<a href="qrect.html#5b3d2b">intersects</a>( <a href=#530>targetRect</a>() ) ) <a href=#526>paintTarget</a>( &p );}void <a name="525"></a>CannonField::paintShot( <a href="qpainter.html">QPainter</a> *p ){ p-><a href="qpainter.html#3e0cc8">setBrush</a>( black ); p-><a href="qpainter.html#0183e4">setPen</a>( NoPen ); p-><a href="qpainter.html#4c0077">drawRect</a>( <a href=#529>shotRect</a>() );}void <a name="526"></a>CannonField::paintTarget( <a href="qpainter.html">QPainter</a> *p ){ p-><a href="qpainter.html#3e0cc8">setBrush</a>( red ); p-><a href="qpainter.html#0183e4">setPen</a>( black ); p-><a href="qpainter.html#4c0077">drawRect</a>( <a href=#530>targetRect</a>() );}const QRect barrelRect(33, -4, 15, 8);void <a name="527"></a>CannonField::paintCannon( <a href="qpainter.html">QPainter</a> *p ){ <a href="qrect.html">QRect</a> cr = cannonRect(); <a href="qpixmap.html">QPixmap</a> pix( cr.<a href="qrect.html#507cd9">size</a>() ); pix.<a href="qpixmap.html#6910a0">fill</a>( this, cr.<a href="qrect.html#349186">topLeft</a>() ); <a href="qpainter.html">QPainter</a> tmp( &pix ); tmp.<a href="qpainter.html#3e0cc8">setBrush</a>( blue ); tmp.<a href="qpainter.html#0183e4">setPen</a>( NoPen ); tmp.<a href="qpainter.html#eb778c">translate</a>( 0, pix.<a href="qpixmap.html#d5bb33">height</a>() - 1 ); tmp.<a href="qpainter.html#3ca7a2">drawPie</a>( <a href="qrect.html">QRect</a>( -35,-35, 70, 70 ), 0, 90*16 ); tmp.<a href="qpainter.html#b5205c">rotate</a>( -ang ); tmp.<a href="qpainter.html#4c0077">drawRect</a>( barrelRect ); tmp.<a href="qpainter.html#365784">end</a>(); p-><a href="qpainter.html#c64b89">drawPixmap</a>( cr.<a href="qrect.html#349186">topLeft</a>(), pix );}<a href="qrect.html">QRect</a> <a name="528"></a>CannonField::cannonRect() const{ <a href="qrect.html">QRect</a> r( 0, 0, 50, 50 ); r.<a href="qrect.html#8df149">moveBottomLeft</a>( <a href="qwidget.html#75ae71">rect</a>().bottomLeft() ); return r;}<a href="qrect.html">QRect</a> <a name="529"></a>CannonField::shotRect() const{ const double gravity = 4; double time = timerCount / 4.0; double velocity = shoot_f; double radians = shoot_ang*3.14159265/180; double velx = velocity*cos( radians ); double vely = velocity*sin( radians ); double x0 = ( barrelRect.right() + 5 )*cos(radians); double y0 = ( barrelRect.right() + 5 )*sin(radians); double x = x0 + velx*time; double y = y0 + vely*time - 0.5*gravity*time*time; <a href="qrect.html">QRect</a> r = QRect( 0, 0, 6, 6 ); r.<a href="qrect.html#03af30">moveCenter</a>( <a href="qpoint.html">QPoint</a>( qRound(x), <a href="qwidget.html#e3c588">height</a>() - 1 - qRound(y) ) ); return r;}<a href="qrect.html">QRect</a> <a name="530"></a>CannonField::targetRect() const{ <a href="qrect.html">QRect</a> r( 0, 0, 20, 10 ); r.<a href="qrect.html#03af30">moveCenter</a>( <a href="qpoint.html">QPoint</a>(target.x(),<a href="qwidget.html#e3c588">height</a>() - 1 - target.y()) ); return r;}<a href="qsizepolicy.html">QSizePolicy</a> <a name="531"></a>CannonField::sizePolicy() const{ return QSizePolicy( QSizePolicy::Expanding, QSizePolicy::Expanding );}</pre><p><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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