- Qt 5.5
- Qt GUI
- Analog Clock Window Example
- main.cpp Example File
- Qt 5.5.1 Reference Documentation

# main.cpp Example File

analogclock/main.cpp

    /****************************************************************************
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    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
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    ** This file is part of the examples of the Qt Toolkit.
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    ** $QT_BEGIN_LICENSE:BSD$
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    #include <QtGui>

    #include "rasterwindow.h"

    class AnalogClockWindow : public RasterWindow
    {
    public:
        AnalogClockWindow();

    protected:
        void timerEvent(QTimerEvent *) Q_DECL_OVERRIDE;
        void render(QPainter *p) Q_DECL_OVERRIDE;

    private:
        int m_timerId;
    };

    AnalogClockWindow::AnalogClockWindow()
    {
        setTitle("Analog Clock");
        resize(200, 200);

        m_timerId = startTimer(1000);
    }

    void AnalogClockWindow::timerEvent(QTimerEvent *event)
    {
        if (event->timerId() == m_timerId)
            renderLater();
    }

    void AnalogClockWindow::render(QPainter *p)
    {
        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);

        p->setRenderHint(QPainter::Antialiasing);
        p->translate(width() / 2, height() / 2);

        int side = qMin(width(), height());
        p->scale(side / 200.0, side / 200.0);

        p->setPen(Qt::NoPen);
        p->setBrush(hourColor);

        QTime time = QTime::currentTime();

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

        p->setPen(hourColor);

        for (int i = 0; i < 12; ++i) {
            p->drawLine(88, 0, 96, 0);
            p->rotate(30.0);
        }
        p->setPen(Qt::NoPen);
        p->setBrush(minuteColor);

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

        p->setPen(minuteColor);

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

    int main(int argc, char **argv)
    {
        QGuiApplication app(argc, argv);

        AnalogClockWindow clock;
        clock.show();

        return app.exec();
    }