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    41 

    42 #include <QtGui>

    43 

    44 #include "bubble.h"

    45 

    46 Bubble::Bubble(const QPointF &position, qreal radius, const QPointF &velocity)

    47     : position(position), vel(velocity), radius(radius)

    48 {

    49     innerColor = randomColor();

    50     outerColor = randomColor();

    51     cache = 0;

    52     updateBrush();

    53 }

    54 

    55 //! [0]

    56 void Bubble::updateCache()

    57 {

    58     if (cache)

    59         delete cache;

    60     cache = new QImage(qRound(radius * 2 + 2), qRound(radius * 2 + 2), QImage::Format_ARGB32);

    61     cache->fill(0x00000000);

    62     QPainter p(cache);

    63     p.setRenderHint(QPainter::HighQualityAntialiasing);

    64     QPen pen(Qt::white);

    65     pen.setWidth(2);

    66     p.setPen(pen);

    67     p.setBrush(brush);

    68     p.drawEllipse(0, 0, int(2*radius), int(2*radius));

    69 }

    70 //! [0]

    71 

    72 Bubble::~Bubble()

    73 {

    74     if (cache)

    75         delete cache;

    76 }

    77 

    78 void Bubble::updateBrush()

    79 {

    80     QRadialGradient gradient(QPointF(radius, radius), radius,

    81                              QPointF(radius*0.5, radius*0.5));

    82 

    83     gradient.setColorAt(0, QColor(255, 255, 255, 255));

    84     gradient.setColorAt(0.25, innerColor);

    85     gradient.setColorAt(1, outerColor);

    86     brush = QBrush(gradient);

    87     updateCache();

    88 }

    89 

    90 //! [1]

    91 void Bubble::drawBubble(QPainter *painter)

    92 {

    93     painter->save();

    94     painter->translate(position.x() - radius, position.y() - radius);

    95     painter->setOpacity(0.8);

    96     painter->drawImage(0, 0, *cache);

    97     painter->restore();

    98 }

    99 //! [1]

   100 

   101 QColor Bubble::randomColor()

   102 {

   103     int red = int(185 + 70.0*qrand()/(RAND_MAX+1.0));

   104     int green = int(185 + 70.0*qrand()/(RAND_MAX+1.0));

   105     int blue = int(205 + 50.0*qrand()/(RAND_MAX+1.0));

   106     int alpha = int(91 + 100.0*qrand()/(RAND_MAX+1.0));

   107 

   108     return QColor(red, green, blue, alpha);

   109 }

   110 

   111 void Bubble::move(const QRect &bbox)

   112 {

   113     position += vel;

   114     qreal leftOverflow = position.x() - radius - bbox.left();

   115     qreal rightOverflow = position.x() + radius - bbox.right();

   116     qreal topOverflow = position.y() - radius - bbox.top();

   117     qreal bottomOverflow = position.y() + radius - bbox.bottom();

   118     

   119     if (leftOverflow < 0.0) {

   120         position.setX(position.x() - 2 * leftOverflow);

   121         vel.setX(-vel.x());

   122     } else if (rightOverflow > 0.0) {

   123         position.setX(position.x() - 2 * rightOverflow);

   124         vel.setX(-vel.x());

   125     }

   126 

   127     if (topOverflow < 0.0) {

   128         position.setY(position.y() - 2 * topOverflow);

   129         vel.setY(-vel.y());

   130     } else if (bottomOverflow > 0.0) {

   131         position.setY(position.y() - 2 * bottomOverflow);

   132         vel.setY(-vel.y());

   133     }

   134 }

   135 

   136 QRectF Bubble::rect()

   137 {

   138     return QRectF(position.x() - radius, position.y() - radius,

   139                   2 * radius, 2 * radius);

   140 }