<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>Qt 4.2: cannonfield.cpp Example File (tutorial/t12/cannonfield.cpp)</title>
<link href="classic.css" rel="stylesheet" type="text/css" />
</head>
<body>
<table border="0" cellpadding="0" cellspacing="0" width="100%">
<tr>
<td align="left" valign="top" width="32"><a href="http://www.trolltech.com/products/qt"><img src="images/qt-logo.png" align="left" width="32" height="32" border="0" /></a></td>
<td width="1"> </td><td class="postheader" 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="groups.html"><font color="#004faf">Grouped Classes</font></a> · <a href="modules.html"><font color="#004faf">Modules</font></a> · <a href="functions.html"><font color="#004faf">Functions</font></a></td>
<td align="right" valign="top" width="230"><a href="http://www.trolltech.com"><img src="images/trolltech-logo.png" align="right" width="203" height="32" border="0" /></a></td></tr></table><h1 align="center">cannonfield.cpp Example File<br /><sup><sup>tutorial/t12/cannonfield.cpp</sup></sup></h1>
<pre> /****************************************************************************
**
** Copyright (C) 2005-2006 Trolltech ASA. All rights reserved.
**
** This file is part of the example classes of the Qt Toolkit.
**
** This file may be used under the terms of the GNU General Public
** License version 2.0 as published by the Free Software Foundation
** and appearing in the file LICENSE.GPL included in the packaging of
** this file. Please review the following information to ensure GNU
** General Public Licensing requirements will be met:
** http:<span class="comment">//www.trolltech.com/products/qt/opensource.html</span>
**
** If you are unsure which license is appropriate for your use, please
** review the following information:
** http:<span class="comment">//www.trolltech.com/products/qt/licensing.html or contact the</span>
** sales department at sales@trolltech.com.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
****************************************************************************/
#include <QDateTime>
#include <QPaintEvent>
#include <QPainter>
#include <QTimer>
#include <math.h>
#include <stdlib.h>
#include "cannonfield.h"
CannonField::CannonField(QWidget *parent)
: QWidget(parent)
{
currentAngle = 45;
currentForce = 0;
timerCount = 0;
autoShootTimer = new QTimer(this);
connect(autoShootTimer, SIGNAL(timeout()), this, SLOT(moveShot()));
shootAngle = 0;
shootForce = 0;
target = QPoint(0, 0);
setPalette(QPalette(QColor(250, 250, 200)));
setAutoFillBackground(true);
newTarget();
}
void CannonField::setAngle(int angle)
{
if (angle < 5)
angle = 5;
if (angle > 70)
angle = 70;
if (currentAngle == angle)
return;
currentAngle = angle;
update(cannonRect());
emit angleChanged(currentAngle);
}
void CannonField::setForce(int force)
{
if (force < 0)
force = 0;
if (currentForce == force)
return;
currentForce = force;
emit forceChanged(currentForce);
}
void CannonField::shoot()
{
if (autoShootTimer->isActive())
return;
timerCount = 0;
shootAngle = currentAngle;
shootForce = currentForce;
autoShootTimer->start(5);
}
void CannonField::newTarget()
{
static bool firstTime = true;
if (firstTime) {
firstTime = false;
QTime midnight(0, 0, 0);
qsrand(midnight.secsTo(QTime::currentTime()));
}
target = QPoint(200 + qrand() % 190, 10 + qrand() % 255);
update();
}
void CannonField::moveShot()
{
QRegion region = shotRect();
++timerCount;
QRect shotR = shotRect();
if (shotR.intersects(targetRect())) {
autoShootTimer->stop();
emit hit();
} else if (shotR.x() > width() || shotR.y() > height()) {
autoShootTimer->stop();
emit missed();
} else {
region = region.unite(shotR);
}
update(region);
}
void CannonField::paintEvent(QPaintEvent * /* event */)
{
QPainter painter(this);
paintCannon(painter);
if (autoShootTimer->isActive())
paintShot(painter);
paintTarget(painter);
}
void CannonField::paintShot(QPainter &painter)
{
painter.setPen(Qt::NoPen);
painter.setBrush(Qt::black);
painter.drawRect(shotRect());
}
void CannonField::paintTarget(QPainter &painter)
{
painter.setPen(Qt::black);
painter.setBrush(Qt::red);
painter.drawRect(targetRect());
}
const QRect barrelRect(30, -5, 20, 10);
void CannonField::paintCannon(QPainter &painter)
{
painter.setPen(Qt::NoPen);
painter.setBrush(Qt::blue);
painter.save();
painter.translate(0, height());
painter.drawPie(QRect(-35, -35, 70, 70), 0, 90 * 16);
painter.rotate(-currentAngle);
painter.drawRect(barrelRect);
painter.restore();
}
QRect CannonField::cannonRect() const
{
QRect result(0, 0, 50, 50);
result.moveBottomLeft(rect().bottomLeft());
return result;
}
QRect CannonField::shotRect() const
{
const double gravity = 4;
double time = timerCount / 20.0;
double velocity = shootForce;
double radians = shootAngle * 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;
QRect result(0, 0, 6, 6);
result.moveCenter(QPoint(qRound(x), height() - 1 - qRound(y)));
return result;
}
QRect CannonField::targetRect() const
{
QRect result(0, 0, 20, 10);
result.moveCenter(QPoint(target.x(), height() - 1 - target.y()));
return result;
}</pre>
<p /><address><hr /><div align="center">
<table width="100%" cellspacing="0" border="0"><tr class="address">
<td width="30%">Copyright © 2006 <a href="trolltech.html">Trolltech</a></td>
<td width="40%" align="center"><a href="trademarks.html">Trademarks</a></td>
<td width="30%" align="right"><div align="right">Qt 4.2.1</div></td>
</tr></table></div></address></body>
</html>
