- Qt 5.5
- Qt Designer Manual
- World Time Clock Plugin Example
- worldtimeclock.cpp Example File
- Qt 5.5.1 Reference Documentation

# worldtimeclock.cpp Example File

worldtimeclockplugin/worldtimeclock.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the examples of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
    ** You may use this file under the terms of the BSD license as follows:
    **
    ** "Redistribution and use in source and binary forms, with or without
    ** modification, are permitted provided that the following conditions are
    ** met:
    **   * Redistributions of source code must retain the above copyright
    **     notice, this list of conditions and the following disclaimer.
    **   * Redistributions in binary form must reproduce the above copyright
    **     notice, this list of conditions and the following disclaimer in
    **     the documentation and/or other materials provided with the
    **     distribution.
    **   * Neither the name of The Qt Company Ltd nor the names of its
    **     contributors may be used to endorse or promote products derived
    **     from this software without specific prior written permission.
    **
    **
    ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
    **
    ** $QT_END_LICENSE$
    **
    ****************************************************************************/

    #include "worldtimeclock.h"

    #include <QMouseEvent>
    #include <QPainter>
    #include <QTimer>

    WorldTimeClock::WorldTimeClock(QWidget *parent)
        : QWidget(parent)
        , timeZoneOffset(0)

    {
        typedef void (QWidget::*WidgetUpdateSlot)();

        QTimer *timer = new QTimer(this);
        connect(timer, &QTimer::timeout, this, static_cast<WidgetUpdateSlot>(&QWidget::update));
        timer->start(1000);

        setWindowTitle(tr("World Time Clock"));
        resize(200, 200);
    }

    void WorldTimeClock::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();
        time = time.addSecs(timeZoneOffset);

        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);
        }

        emit updated(time);
    }

    void WorldTimeClock::setTimeZone(int hourOffset)
    {
        timeZoneOffset = qMin(qMax(-12, hourOffset), 12) * 3600;
        update();
    }