Source code for tutorial 12: cannon.cpp
/****************************************************************
**
** Implementation CannonField class, Qt tutorial 12
**
****************************************************************/
#include "cannon.h"
#include <qpainter.h>
#include <qpixmap.h>
#include <qdatetm.h>
#include <math.h>
#include <stdlib.h>
CannonField::CannonField( QWidget *parent, const char *name )
: QWidget( parent, name )
{
ang = 45;
f = 0;
shooting = FALSE;
timerCount = 0;
shoot_ang = 0;
shoot_f = 0;
newTarget();
}
void CannonField::setAngle( int degrees )
{
if ( degrees < 5 )
degrees = 5;
if ( degrees > 70 )
degrees = 70;
if ( ang == degrees )
return;
ang = degrees;
repaint( cannonRect(), FALSE );
emit angleChanged( ang );
}
void CannonField::setForce( int newton )
{
if ( newton < 0 )
newton = 0;
if ( f == newton )
return;
f = newton;
emit forceChanged( f );
}
void CannonField::shoot()
{
if ( shooting )
return;
timerCount = 0;
shoot_ang = ang;
shoot_f = f;
shooting = TRUE;
startTimer( 50 );
}
void CannonField::newTarget()
{
static bool first_time = TRUE;
if ( first_time ) {
first_time = FALSE;
QTime midnight( 0, 0, 0 );
srand( midnight.secsTo(QTime::currentTime()) );
}
erase( targetRect() );
target = QPoint( 200 + rand() % 190,
10 + rand() % 255 );
repaint( targetRect() );
}
void CannonField::timerEvent( QTimerEvent * )
{
erase( shotRect() );
timerCount++;
QRect shotR = shotRect();
if ( shotR.intersects( targetRect() ) ) {
stopShooting();
emit hit();
return;
}
if ( shotR.x() > width() || shotR.y() > height() ) {
stopShooting();
emit missed();
return;
}
repaint( shotR, FALSE );
}
void CannonField::paintEvent( QPaintEvent *e )
{
QRect updateR = e->rect();
QPainter p;
p.begin( this );
if ( updateR.intersects( cannonRect() ) )
paintCannon( &p );
if ( shooting && updateR.intersects( shotRect() ) )
paintShot( &p );
if ( updateR.intersects( targetRect() ) )
paintTarget( &p );
p.end();
}
void CannonField::stopShooting()
{
shooting = FALSE;
killTimers();
}
void CannonField::paintShot( QPainter *p )
{
p->setBrush( black );
p->setPen( NoPen );
p->drawRect( shotRect() );
}
void CannonField::paintTarget( QPainter *p )
{
p->setBrush( red );
p->setPen( black );
p->drawRect( targetRect() );
}
const QRect barrel_rect(33, -4, 15, 8);
void CannonField::paintCannon( QPainter *p )
{
QRect cr = cannonRect();
QPixmap pix( cr.size() );
QPainter tmp;
pix.fill( this, cr.topLeft() );
tmp.begin( &pix );
tmp.setBrush( blue );
tmp.setPen( NoPen );
tmp.translate( 0, pix.height() - 1 );
tmp.drawPie( QRect( -35,-35, 70, 70 ), 0, 90*16 );
tmp.rotate( -ang );
tmp.drawRect( barrel_rect );
tmp.end();
p->drawPixmap( cr.topLeft(), pix );
}
QRect CannonField::cannonRect() const
{
QRect r( 0, 0, 50, 50 );
r.moveBottomLeft( rect().bottomLeft() );
return r;
}
QRect CannonField::shotRect() const
{
const double gravity = 4;
double time = timerCount / 4.0;
double velocity = shoot_f/0.7;
double radians = shoot_ang*3.14159265/180;
double velx = velocity*cos( radians );
double vely = velocity*sin( radians );
double x0 = ( barrel_rect.right() + 5 )*cos(radians);
double y0 = ( barrel_rect.right() + 5 )*sin(radians);
double x = x0 + velx*time;
double y = y0 + vely*time - gravity*time*time;
QRect r = QRect( 0, 0, 6, 6 );
r.moveCenter( QPoint( qRound(x), height() - 1 - qRound(y) ) );
return r;
}
QRect CannonField::targetRect() const
{
QRect r( 0, 0, 20, 10 );
r.moveCenter( QPoint(target.x(),height() - 1 - target.y()) );
return r;
}
Generated at 16:51, 1996/09/24 for Qt version 1.0 by the webmaster at Troll Tech