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chasewidget.cpp Example File
demos/browser/chasewidget.cpp

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 #include "chasewidget.h"

 #include <QtCore/QPoint>

 #include <QtGui/QApplication>
 #include <QtGui/QPainter>
 #include <QtGui/QPaintEvent>
 #include <QtGui/QHideEvent>
 #include <QtGui/QShowEvent>

 ChaseWidget::ChaseWidget(QWidget *parent, QPixmap pixmap, bool pixmapEnabled)
     : QWidget(parent)
     , m_segment(0)
     , m_delay(100)
     , m_step(40)
     , m_timerId(-1)
     , m_animated(false)
     , m_pixmap(pixmap)
     , m_pixmapEnabled(pixmapEnabled)
 {
 }

 ChaseWidget::~ChaseWidget()
 {
 }

 void ChaseWidget::setAnimated(bool val)
 {
     if (m_animated == val)
         return;
     m_animated = val;
     if (m_timerId != -1) {
         killTimer(m_timerId);
         m_timerId = -1;
     }
     if (m_animated) {
         m_segment = 0;
         m_timerId = startTimer(m_delay);
     }
     update();
 }

 void ChaseWidget::showEvent(QShowEvent *e)
 {
     Q_UNUSED(e);
 }

 void ChaseWidget::hideEvent(QHideEvent *e)
 {
     Q_UNUSED(e);
 }

 void ChaseWidget::paintEvent(QPaintEvent *)
 {
     QPainter p(this);

     if (m_pixmapEnabled && !m_pixmap.isNull()) {
         p.drawPixmap(0, 0, m_pixmap);
         return;
     }

     const int extent = qMin(width() - 8, height() - 8);
     const int displ = extent / 4;
     const int ext = extent / 4 - 1;

     p.setRenderHint(QPainter::Antialiasing, true);

     if(m_animated)
         p.setPen(Qt::gray);
     else
         p.setPen(QPen(palette().dark().color()));

     p.translate(width() / 2, height() / 2); // center

     for (int segment = 0; segment < segmentCount(); segment++) {
         p.rotate(QApplication::isRightToLeft() ? m_step : -m_step);
         if(m_animated)
             p.setBrush(colorForSegment(segment));
         else
             p.setBrush(palette().background());
         p.drawEllipse(QRect(displ, -ext / 2, ext, ext));
     }
 }

 QSize ChaseWidget::sizeHint() const
 {
     return QSize(32, 32);
 }

 void ChaseWidget::timerEvent(QTimerEvent *e)
 {
     if (e->timerId() == m_timerId) {
         m_segment++;
         update();
     }
 }

 QColor ChaseWidget::colorForSegment(int seg) const
 {
     int index = ((seg + m_segment) % segmentCount());
     int comp = qMax(0, 255 - (index * (255 / segmentCount())));
     return QColor(comp, comp, comp, 255);
 }

 int ChaseWidget::segmentCount() const
 {
     return 360 / m_step;
 }

 void ChaseWidget::setPixmapEnabled(bool enable)
 {
     m_pixmapEnabled = enable;
 }


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Qt 4.4.0-beta1