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<pre>/****************************************************************
**
** Implementation CannonField class, Qt tutorial 11
**
****************************************************************/

#include "cannon.h"
#include &lt;<a href="qtimer-h.html">qtimer.h</a>&gt;
#include &lt;<a href="qpainter-h.html">qpainter.h</a>&gt;
#include &lt;<a href="qpixmap-h.html">qpixmap.h</a>&gt;

#include &lt;math.h&gt;


<a name="f57"></a>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#connect">connect</a>( autoShootTimer, SIGNAL(<a href="qtimer.html#timeout">timeout</a>()),
             this, SLOT(moveShot()) );
    shoot_ang = 0;
    shoot_f = 0;
    <a href="qwidget.html#setPalette">setPalette</a>( QPalette( QColor( 250, 250, 200) ) );
}


void <a name="f58"></a>CannonField::setAngle( int degrees )
{
    if ( degrees &lt; 5 )
        degrees = 5;
    if ( degrees &gt; 70 )
        degrees = 70;
    if ( ang == degrees )
        return;
    ang = degrees;
    <a href="qwidget.html#repaint">repaint</a>( cannonRect(), FALSE );
    emit angleChanged( ang );
}


void <a name="f59"></a>CannonField::setForce( int newton )
{
    if ( newton &lt; 0 )
        newton = 0;
    if ( f == newton )
        return;
    f = newton;
    emit forceChanged( f );
}


void <a name="f60"></a>CannonField::shoot()
{
    if ( autoShootTimer-&gt;<a href="qtimer.html#isActive">isActive</a>() )
        return;
    timerCount = 0;
    shoot_ang = ang;
    shoot_f = f;
    autoShootTimer-&gt;<a href="qtimer.html#start">start</a>( 50 );
}


void <a name="f61"></a>CannonField::moveShot()
{
    <a href="qregion.html">QRegion</a> r( shotRect() );
    timerCount++;

    <a href="qrect.html">QRect</a> shotR = shotRect();

    if ( shotR.<a href="qrect.html#x">x</a>() &gt; width() || shotR.<a href="qrect.html#y">y</a>() &gt; height() )
        autoShootTimer-&gt;<a href="qtimer.html#stop">stop</a>();
    else
        r = r.<a href="qrect.html#unite">unite</a>( QRegion( shotR ) );
    <a href="qwidget.html#repaint">repaint</a>( r );
}


void CannonField::<a href="qwidget.html#paintEvent">paintEvent</a>( <a href="qpaintevent.html">QPaintEvent</a> *e )
{
    <a href="qrect.html">QRect</a> updateR = e-&gt;<a href="qpaintevent.html#rect">rect</a>();
    <a href="qpainter.html">QPainter</a> p( this );

    if ( updateR.<a href="qrect.html#intersects">intersects</a>( cannonRect() ) )
        paintCannon( &amp;p );
    if ( autoShootTimer-&gt;<a href="qtimer.html#isActive">isActive</a>() &amp;&amp;
         updateR.<a href="qrect.html#intersects">intersects</a>( shotRect() ) )
        paintShot( &amp;p );
}


void <a name="f62"></a>CannonField::paintShot( <a href="qpainter.html">QPainter</a> *p )
{
    p-&gt;<a href="qpainter.html#setBrush">setBrush</a>( black );
    p-&gt;<a href="qpainter.html#setPen">setPen</a>( NoPen );
    p-&gt;<a href="qpainter.html#drawRect">drawRect</a>( shotRect() );
}


const <a href="qrect.html">QRect</a> barrelRect(33, -4, 15, 8);

void <a name="f63"></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#size">size</a>() );
    pix.<a href="qpixmap.html#fill">fill</a>( this, cr.<a href="qrect.html#topLeft">topLeft</a>() );

    <a href="qpainter.html">QPainter</a> tmp( &amp;pix );
    tmp.<a href="qpainter.html#setBrush">setBrush</a>( blue );
    tmp.<a href="qpainter.html#setPen">setPen</a>( NoPen );

    tmp.<a href="qpainter.html#translate">translate</a>( 0, pix.<a href="qpixmap.html#height">height</a>() - 1 );
    tmp.<a href="qpainter.html#drawPie">drawPie</a>( QRect( -35,-35, 70, 70 ), 0, 90*16 );
    tmp.<a href="qpainter.html#rotate">rotate</a>( -ang );
    tmp.<a href="qpainter.html#drawRect">drawRect</a>( barrelRect );
    tmp.<a href="qpainter.html#end">end</a>();

    p-&gt;<a href="qpainter.html#drawPixmap">drawPixmap</a>( cr.<a href="qrect.html#topLeft">topLeft</a>(), pix );
}


QRect <a name="f64"></a>CannonField::cannonRect() const
{
    <a href="qrect.html">QRect</a> r( 0, 0, 50, 50 );
    r.<a href="qrect.html#moveBottomLeft">moveBottomLeft</a>( <a href="qwidget.html#rect">rect</a>().bottomLeft() );
    return r;
}


QRect <a name="f65"></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.<a href="qrect.html#right">right</a>()  + 5 )*cos(radians);
    double y0        = ( barrelRect.<a href="qrect.html#right">right</a>()  + 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#moveCenter">moveCenter</a>( QPoint( qRound(x), height() - 1 - qRound(y) ) );
    return r;
}


QSizePolicy CannonField::<a href="qwidget.html#sizePolicy">sizePolicy</a>() const
{
    return QSizePolicy( QSizePolicy::Expanding, QSizePolicy::Expanding );
}
</pre><!-- eof -->
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