- Qt 5.5
- Qt WebEngine Widgets
- WebEngine Tab Browser Example
- chasewidget.cpp Example File
- Qt 5.5.1 Reference Documentation

# chasewidget.cpp Example File

browser/chasewidget.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the demonstration applications of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:LGPL$
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    ** GNU Lesser General Public License Usage
    ** Alternatively, this file may be used under the terms of the GNU Lesser
    ** General Public License version 2.1 as published by the Free Software
    ** Foundation and appearing in the file LICENSE.LGPL included in the
    ** packaging of this file. Please review the following information to
    ** ensure the GNU Lesser General Public License version 2.1 requirements
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    ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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    ** GNU General Public License Usage
    ** Alternatively, this file may be used under the terms of the GNU
    ** General Public License version 3.0 as published by the Free Software
    ** Foundation and appearing in the file LICENSE.GPL included in the
    ** packaging of this file. Please review the following information to
    ** ensure the GNU General Public License version 3.0 requirements will be
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    #include "chasewidget.h"

    #include <QtCore/QPoint>

    #include <QtWidgets/QApplication>
    #include <QtGui/QHideEvent>
    #include <QtGui/QPainter>
    #include <QtGui/QPaintEvent>
    #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)
    {
    }

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

    void ChaseWidget::paintEvent(QPaintEvent *event)
    {
        Q_UNUSED(event);
        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 *event)
    {
        if (event->timerId() == m_timerId) {
            ++m_segment;
            update();
        }
        QWidget::timerEvent(event);
    }

    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;
    }