shapedclock.cpp Example File
widgets/shapedclock/shapedclock.cpp

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 #include <QtGui>

 #include "shapedclock.h"

 ShapedClock::ShapedClock(QWidget *parent)
     : QWidget(parent, Qt::FramelessWindowHint | Qt::WindowSystemMenuHint)
 {
     QTimer *timer = new QTimer(this);
     connect(timer, SIGNAL(timeout()), this, SLOT(update()));
     timer->start(1000);

     QAction *quitAction = new QAction(tr("E&xit"), this);
     quitAction->setShortcut(tr("Ctrl+Q"));
     connect(quitAction, SIGNAL(triggered()), qApp, SLOT(quit()));
     addAction(quitAction);

     setContextMenuPolicy(Qt::ActionsContextMenu);
     setToolTip(tr("Drag the clock with the left mouse button.\n"
                   "Use the right mouse button to open a context menu."));
     setWindowTitle(tr("Shaped Analog Clock"));
 }

 void ShapedClock::mousePressEvent(QMouseEvent *event)
 {
     if (event->button() == Qt::LeftButton) {
         dragPosition = event->globalPos() - frameGeometry().topLeft();
         event->accept();
     }
 }

 void ShapedClock::mouseMoveEvent(QMouseEvent *event)
 {
     if (event->buttons() & Qt::LeftButton) {
         move(event->globalPos() - dragPosition);
         event->accept();
     }
 }

 void ShapedClock::paintEvent(QPaintEvent *)
 {
     static const QPoint hourHand[3] = {
         QPoint(7, 8),
         QPoint(-7, 8),
         QPoint(0, -40)
     };
     static const QPoint minuteHand[3] = {
         QPoint(7, 8),
         QPoint(-7, 8),
         QPoint(0, -70)
     };

     QColor hourColor(127, 0, 127);
     QColor minuteColor(0, 127, 127, 191);

     int side = qMin(width(), height());
     QTime time = QTime::currentTime();

     QPainter painter(this);
     painter.setRenderHint(QPainter::Antialiasing);
     painter.translate(width() / 2, height() / 2);
     painter.scale(side / 200.0, side / 200.0);

     painter.setPen(Qt::NoPen);
     painter.setBrush(hourColor);

     painter.save();
     painter.rotate(30.0 * ((time.hour() + time.minute() / 60.0)));
     painter.drawConvexPolygon(hourHand, 3);
     painter.restore();

     painter.setPen(hourColor);

     for (int i = 0; i < 12; ++i) {
         painter.drawLine(88, 0, 96, 0);
         painter.rotate(30.0);
     }

     painter.setPen(Qt::NoPen);
     painter.setBrush(minuteColor);

     painter.save();
     painter.rotate(6.0 * (time.minute() + time.second() / 60.0));
     painter.drawConvexPolygon(minuteHand, 3);
     painter.restore();

     painter.setPen(minuteColor);

     for (int j = 0; j < 60; ++j) {
         if ((j % 5) != 0)
             painter.drawLine(92, 0, 96, 0);
         painter.rotate(6.0);
     }
 }

 void ShapedClock::resizeEvent(QResizeEvent * /* event */)
 {
     int side = qMin(width(), height());
     QRegion maskedRegion(width() / 2 - side / 2, height() / 2 - side / 2, side,
                          side, QRegion::Ellipse);
     setMask(maskedRegion);
 }

 QSize ShapedClock::sizeHint() const
 {
     return QSize(100, 100);
 }