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# t13/cannon.cpp Example File

    /****************************************************************
    **
    ** Implementation CannonField class, TQt tutorial 13
    **
    ****************************************************************/

    #include "cannon.h"
    #include <ntqtimer.h>
    #include <ntqpainter.h>
    #include <ntqpixmap.h>
    #include <ntqdatetime.h>

    #include <math.h>
    #include <stdlib.h>

    CannonField::CannonField( TQWidget *parent, const char *name )
            : TQWidget( parent, name )
    {
        ang = 45;
        f = 0;
        timerCount = 0;
        autoShootTimer = new TQTimer( this, "movement handler" );
        connect( autoShootTimer, TQ_SIGNAL(timeout()),
                 this, TQ_SLOT(moveShot()) );
        shoot_ang = 0;
        shoot_f = 0;
        target = TQPoint( 0, 0 );
        gameEnded = false;
        setPalette( TQPalette( TQColor( 250, 250, 200) ) );
        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 ( isShooting() )
            return;
        timerCount = 0;
        shoot_ang = ang;
        shoot_f = f;
        autoShootTimer->start( 50 );
        emit canShoot( false );
    }

    void  CannonField::newTarget()
    {
        static bool first_time = true;
        if ( first_time ) {
            first_time = false;
            TQTime midnight( 0, 0, 0 );
            srand( midnight.secsTo(TQTime::currentTime()) );
        }
        TQRegion r( targetRect() );
        target = TQPoint( 200 + rand() % 190,
                         10  + rand() % 255 );
        repaint( r.unite( targetRect() ) );
    }

    void CannonField::setGameOver()
    {
        if ( gameEnded )
            return;
        if ( isShooting() )
            autoShootTimer->stop();
        gameEnded = true;
        repaint();
    }

    void CannonField::restartGame()
    {
        if ( isShooting() )
            autoShootTimer->stop();
        gameEnded = false;
        repaint();
        emit canShoot( true );
    }

    void CannonField::moveShot()
    {
        TQRegion r( shotRect() );
        timerCount++;

        TQRect shotR = shotRect();

        if ( shotR.intersects( targetRect() ) ) {
            autoShootTimer->stop();
            emit hit();
            emit canShoot( true );
        } else if ( shotR.x() > width() || shotR.y() > height() ) {
            autoShootTimer->stop();
            emit missed();
            emit canShoot( true );
        } else {
            r = r.unite( TQRegion( shotR ) );
        }

        repaint( r );
    }

    void CannonField::paintEvent( TQPaintEvent *e )
    {
        TQRect updateR = e->rect();
        TQPainter p( this );

        if ( gameEnded ) {
            p.setPen( black );
            p.setFont( TQFont( "Courier", 48, TQFont::Bold ) );
            p.drawText( rect(), AlignCenter, "Game Over" );
        }
        if ( updateR.intersects( cannonRect() ) )
            paintCannon( &p );
        if ( isShooting() && updateR.intersects( shotRect() ) )
            paintShot( &p );
        if ( !gameEnded && updateR.intersects( targetRect() ) )
            paintTarget( &p );
    }

    void CannonField::paintShot( TQPainter *p )
    {
        p->setBrush( black );
        p->setPen( NoPen );
        p->drawRect( shotRect() );
    }

    void CannonField::paintTarget( TQPainter *p )
    {
        p->setBrush( red );
        p->setPen( black );
        p->drawRect( targetRect() );
    }

    const TQRect barrelRect(33, -4, 15, 8);

    void CannonField::paintCannon( TQPainter *p )
    {
        TQRect cr = cannonRect();
        TQPixmap pix( cr.size() );
        pix.fill( this, cr.topLeft() );

        TQPainter tmp( &pix );
        tmp.setBrush( blue );
        tmp.setPen( NoPen );

        tmp.translate( 0, pix.height() - 1 );
        tmp.drawPie( TQRect( -35,-35, 70, 70 ), 0, 90*16 );
        tmp.rotate( -ang );
        tmp.drawRect( barrelRect );
        tmp.end();

        p->drawPixmap( cr.topLeft(), pix );
    }

    TQRect CannonField::cannonRect() const
    {
        TQRect r( 0, 0, 50, 50 );
        r.moveBottomLeft( rect().bottomLeft() );
        return r;
    }

    TQRect 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;

        TQRect r = TQRect( 0, 0, 6, 6 );
        r.moveCenter( TQPoint( tqRound(x), height() - 1 - tqRound(y) ) );
        return r;
    }

    TQRect CannonField::targetRect() const
    {
        TQRect r( 0, 0, 20, 10 );
        r.moveCenter( TQPoint(target.x(),height() - 1 - target.y()) );
        return r;
    }

    bool CannonField::isShooting() const
    {
        return autoShootTimer->isActive();
    }

    TQSizePolicy CannonField::sizePolicy() const
    {
        return TQSizePolicy( TQSizePolicy::Expanding, TQSizePolicy::Expanding );
    }