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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 - t11/cannon.cpp</title>
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<h1 align=center>Source code for <a href="t11.html">tutorial 11</a>: cannon.cpp</h1><br clear="all">
<hr> <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;

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#7f8e37">connect</a>( autoShootTimer, SIGNAL(timeout()),
             this, SLOT(<a href=#499>moveShot</a>()) );
    shoot_ang = 0;
    shoot_f = 0;
    <a href="qwidget.html#d7e4b9">setPalette</a>( <a href="qpalette.html">QPalette</a>( <a href="qcolor.html">QColor</a>( 250, 250, 200) ) );
}

void <a name="496"></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#7569b1">repaint</a>( cannonRect(), FALSE );
    emit angleChanged( ang );
}

void <a name="497"></a>CannonField::setForce( int newton )
{
    if ( newton &lt; 0 )
        newton = 0;
    if ( f == newton )
        return;
    f = newton;
    emit forceChanged( f );
}

void <a name="498"></a>CannonField::shoot()
{
    if ( autoShootTimer-&gt;isActive() )
        return;
    timerCount = 0;
    shoot_ang = ang;
    shoot_f = f;
    autoShootTimer-&gt;start( 50 );
}

void <a name="499"></a>CannonField::moveShot()
{
    <a href="qregion.html">QRegion</a> r( <a href=#504>shotRect</a>() );
    timerCount++;

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

    if ( shotR.<a href="qrect.html#fccae7">x</a>() &gt; width() || shotR.<a href="qrect.html#f448f7">y</a>() &gt; height() )
        autoShootTimer-&gt;stop();
    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="500"></a>CannonField::paintEvent( <a href="qpaintevent.html">QPaintEvent</a> *e )
{
    <a href="qrect.html">QRect</a> updateR = e-&gt;<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=#503>cannonRect</a>() ) )
        <a href=#502>paintCannon</a>( &amp;p );
    if ( autoShootTimer-&gt;isActive() &amp;&amp;
         updateR.<a href="qrect.html#5b3d2b">intersects</a>( <a href=#504>shotRect</a>() ) )
        <a href=#501>paintShot</a>( &amp;p );
}

void <a name="501"></a>CannonField::paintShot( <a href="qpainter.html">QPainter</a> *p )
{
    p-&gt;<a href="qpainter.html#3e0cc8">setBrush</a>( black );
    p-&gt;<a href="qpainter.html#0183e4">setPen</a>( NoPen );
    p-&gt;<a href="qpainter.html#4c0077">drawRect</a>( <a href=#504>shotRect</a>() );
}

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

void <a name="502"></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( &amp;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-&gt;<a href="qpainter.html#c64b89">drawPixmap</a>( cr.<a href="qrect.html#349186">topLeft</a>(), pix );
}

<a href="qrect.html">QRect</a> <a name="503"></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="504"></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="qsizepolicy.html">QSizePolicy</a> <a name="505"></a>CannonField::sizePolicy() const
{
    return QSizePolicy( QSizePolicy::Expanding, QSizePolicy::Expanding );
}
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