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32<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>t12/cannon.cpp Example File</h1>
33
34
35<pre>/****************************************************************
36**
37** Implementation CannonField class, Qt tutorial 12
38**
39****************************************************************/
40
41#include "cannon.h"
42#include &lt;<a href="qtimer-h.html">qtimer.h</a>&gt;
43#include &lt;<a href="qpainter-h.html">qpainter.h</a>&gt;
44#include &lt;<a href="qpixmap-h.html">qpixmap.h</a>&gt;
45#include &lt;<a href="qdatetime-h.html">qdatetime.h</a>&gt;
46
47#include &lt;math.h&gt;
48#include &lt;stdlib.h&gt;
49
50
51<a name="f74"></a>CannonField::CannonField( <a href="qwidget.html">QWidget</a> *parent, const char *name )
52 : <a href="qwidget.html">QWidget</a>( parent, name )
53{
54 ang = 45;
55 f = 0;
56 timerCount = 0;
57 autoShootTimer = new <a href="qtimer.html">QTimer</a>( this, "movement handler" );
58 <a href="qobject.html#connect">connect</a>( autoShootTimer, SIGNAL(<a href="qtimer.html#timeout">timeout</a>()),
59 this, SLOT(moveShot()) );
60 shoot_ang = 0;
61 shoot_f = 0;
62 target = QPoint( 0, 0 );
63 <a href="qwidget.html#setPalette">setPalette</a>( QPalette( QColor( 250, 250, 200) ) );
64 newTarget();
65}
66
67
68void <a name="f75"></a>CannonField::setAngle( int degrees )
69{
70 if ( degrees &lt; 5 )
71 degrees = 5;
72 if ( degrees &gt; 70 )
73 degrees = 70;
74 if ( ang == degrees )
75 return;
76 ang = degrees;
77 <a href="qwidget.html#repaint">repaint</a>( cannonRect(), FALSE );
78 emit angleChanged( ang );
79}
80
81
82void <a name="f76"></a>CannonField::setForce( int newton )
83{
84 if ( newton &lt; 0 )
85 newton = 0;
86 if ( f == newton )
87 return;
88 f = newton;
89 emit forceChanged( f );
90}
91
92
93void <a name="f77"></a>CannonField::shoot()
94{
95 if ( autoShootTimer-&gt;<a href="qtimer.html#isActive">isActive</a>() )
96 return;
97 timerCount = 0;
98 shoot_ang = ang;
99 shoot_f = f;
100 autoShootTimer-&gt;<a href="qtimer.html#start">start</a>( 50 );
101}
102
103
104void <a name="f78"></a>CannonField::newTarget()
105{
106 static bool first_time = TRUE;
107 if ( first_time ) {
108 first_time = FALSE;
109 <a href="qtime.html">QTime</a> midnight( 0, 0, 0 );
110 srand( midnight.<a href="qtime.html#secsTo">secsTo</a>(QTime::<a href="qtime.html#currentTime">currentTime</a>()) );
111 }
112 <a href="qregion.html">QRegion</a> r( targetRect() );
113 target = QPoint( 200 + rand() % 190,
114 10 + rand() % 255 );
115 <a href="qwidget.html#repaint">repaint</a>( r.<a href="qrect.html#unite">unite</a>( targetRect() ) );
116}
117
118
119void <a name="f79"></a>CannonField::moveShot()
120{
121 <a href="qregion.html">QRegion</a> r( shotRect() );
122 timerCount++;
123
124 <a href="qrect.html">QRect</a> shotR = shotRect();
125
126 if ( shotR.<a href="qrect.html#intersects">intersects</a>( targetRect() ) ) {
127 autoShootTimer-&gt;<a href="qtimer.html#stop">stop</a>();
128 emit hit();
129 } else if ( shotR.<a href="qrect.html#x">x</a>() &gt; width() || shotR.<a href="qrect.html#y">y</a>() &gt; height() ) {
130 autoShootTimer-&gt;<a href="qtimer.html#stop">stop</a>();
131 emit missed();
132 } else {
133 r = r.<a href="qrect.html#unite">unite</a>( QRegion( shotR ) );
134 }
135
136 <a href="qwidget.html#repaint">repaint</a>( r );
137}
138
139
140void CannonField::<a href="qwidget.html#paintEvent">paintEvent</a>( <a href="qpaintevent.html">QPaintEvent</a> *e )
141{
142 <a href="qrect.html">QRect</a> updateR = e-&gt;<a href="qpaintevent.html#rect">rect</a>();
143 <a href="qpainter.html">QPainter</a> p( this );
144
145 if ( updateR.<a href="qrect.html#intersects">intersects</a>( cannonRect() ) )
146 paintCannon( &amp;p );
147 if ( autoShootTimer-&gt;<a href="qtimer.html#isActive">isActive</a>() &amp;&amp;
148 updateR.<a href="qrect.html#intersects">intersects</a>( shotRect() ) )
149 paintShot( &amp;p );
150 if ( updateR.<a href="qrect.html#intersects">intersects</a>( targetRect() ) )
151 paintTarget( &amp;p );
152}
153
154
155void <a name="f80"></a>CannonField::paintShot( <a href="qpainter.html">QPainter</a> *p )
156{
157 p-&gt;<a href="qpainter.html#setBrush">setBrush</a>( black );
158 p-&gt;<a href="qpainter.html#setPen">setPen</a>( NoPen );
159 p-&gt;<a href="qpainter.html#drawRect">drawRect</a>( shotRect() );
160}
161
162
163void <a name="f81"></a>CannonField::paintTarget( <a href="qpainter.html">QPainter</a> *p )
164{
165 p-&gt;<a href="qpainter.html#setBrush">setBrush</a>( red );
166 p-&gt;<a href="qpainter.html#setPen">setPen</a>( black );
167 p-&gt;<a href="qpainter.html#drawRect">drawRect</a>( targetRect() );
168}
169
170
171const <a href="qrect.html">QRect</a> barrelRect(33, -4, 15, 8);
172
173void <a name="f82"></a>CannonField::paintCannon( <a href="qpainter.html">QPainter</a> *p )
174{
175 <a href="qrect.html">QRect</a> cr = cannonRect();
176 <a href="qpixmap.html">QPixmap</a> pix( cr.<a href="qrect.html#size">size</a>() );
177 pix.<a href="qpixmap.html#fill">fill</a>( this, cr.<a href="qrect.html#topLeft">topLeft</a>() );
178
179 <a href="qpainter.html">QPainter</a> tmp( &amp;pix );
180 tmp.<a href="qpainter.html#setBrush">setBrush</a>( blue );
181 tmp.<a href="qpainter.html#setPen">setPen</a>( NoPen );
182
183 tmp.<a href="qpainter.html#translate">translate</a>( 0, pix.<a href="qpixmap.html#height">height</a>() - 1 );
184 tmp.<a href="qpainter.html#drawPie">drawPie</a>( QRect( -35,-35, 70, 70 ), 0, 90*16 );
185 tmp.<a href="qpainter.html#rotate">rotate</a>( -ang );
186 tmp.<a href="qpainter.html#drawRect">drawRect</a>( barrelRect );
187 tmp.<a href="qpainter.html#end">end</a>();
188
189 p-&gt;<a href="qpainter.html#drawPixmap">drawPixmap</a>( cr.<a href="qrect.html#topLeft">topLeft</a>(), pix );
190}
191
192
193QRect <a name="f83"></a>CannonField::cannonRect() const
194{
195 <a href="qrect.html">QRect</a> r( 0, 0, 50, 50 );
196 r.<a href="qrect.html#moveBottomLeft">moveBottomLeft</a>( <a href="qwidget.html#rect">rect</a>().bottomLeft() );
197 return r;
198}
199
200
201QRect <a name="f84"></a>CannonField::shotRect() const
202{
203 const double gravity = 4;
204
205 double time = timerCount / 4.0;
206 double velocity = shoot_f;
207 double radians = shoot_ang*3.14159265/180;
208
209 double velx = velocity*cos( radians );
210 double vely = velocity*sin( radians );
211 double x0 = ( barrelRect.<a href="qrect.html#right">right</a>() + 5 )*cos(radians);
212 double y0 = ( barrelRect.<a href="qrect.html#right">right</a>() + 5 )*sin(radians);
213 double x = x0 + velx*time;
214 double y = y0 + vely*time - 0.5*gravity*time*time;
215
216 <a href="qrect.html">QRect</a> r = QRect( 0, 0, 6, 6 );
217 r.<a href="qrect.html#moveCenter">moveCenter</a>( QPoint( qRound(x), height() - 1 - qRound(y) ) );
218 return r;
219}
220
221
222QRect <a name="f85"></a>CannonField::targetRect() const
223{
224 <a href="qrect.html">QRect</a> r( 0, 0, 20, 10 );
225 r.<a href="qrect.html#moveCenter">moveCenter</a>( QPoint(target.x(),height() - 1 - target.y()) );
226 return r;
227}
228
229
230QSizePolicy CannonField::<a href="qwidget.html#sizePolicy">sizePolicy</a>() const
231{
232 return QSizePolicy( QSizePolicy::Expanding, QSizePolicy::Expanding );
233}
234</pre><!-- eof -->
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