Qt 4.8: main.cpp Example File (demos/embedded/flickable/main.cpp)

Qt Reference Documentation

- Qt 4.8
- ALL VERSIONS

- A
- A
- A
- Print

# main.cpp Example File

demos/embedded/flickable/main.cpp

     /****************************************************************************
     **
     ** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
     ** Contact: http://www.qt-project.org/legal
     **
     ** This file is part of the demonstration applications of the Qt Toolkit.
     **
     ** $QT_BEGIN_LICENSE:LGPL$
     ** Commercial License Usage
     ** Licensees holding valid commercial Qt licenses may use this file in
     ** accordance with the commercial license agreement provided with the
     ** Software or, alternatively, in accordance with the terms contained in
     ** a written agreement between you and Digia.  For licensing terms and
     ** conditions see http://qt.digia.com/licensing.  For further information
     ** use the contact form at http://qt.digia.com/contact-us.
     **
     ** 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
     ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
     **
     ** In addition, as a special exception, Digia gives you certain additional
     ** rights.  These rights are described in the Digia Qt LGPL Exception
     ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
     **
     ** 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
     ** met: http://www.gnu.org/copyleft/gpl.html.
     **
     **
     ** $QT_END_LICENSE$
     **
     ****************************************************************************/

     #include <QtCore>
     #include <QtGui>

     #include "flickable.h"

     // Returns a list of two-word color names
     static QStringList colorPairs(int max)
     {
         // capitalize the first letter
         QStringList colors = QColor::colorNames();
         colors.removeAll("transparent");
         int num = colors.count();
         for (int c = 0; c < num; ++c)
             colors[c] = colors[c][0].toUpper() + colors[c].mid(1);

         // combine two colors, e.g. "lime skyblue"
         QStringList combinedColors;
         for (int i = 0; i < num; ++i)
             for (int j = 0; j < num; ++j)
                 combinedColors << QString("%1 %2").arg(colors[i]).arg(colors[j]);

         // randomize it
         colors.clear();
         while (combinedColors.count()) {
             int i = qrand() % combinedColors.count();
             colors << combinedColors[i];
             combinedColors.removeAt(i);
             if (colors.count() == max)
                 break;
         }

         return colors;
     }

     class ColorList : public QWidget, public Flickable
     {
         Q_OBJECT

     public:
         ColorList(QWidget *parent = 0)
                 : QWidget(parent) {
             m_offset = 0;
             m_height = QFontMetrics(font()).height() + 5;
             m_highlight = -1;
             m_selected = -1;

             QStringList colors = colorPairs(999);
             for (int i = 0; i < colors.count(); ++i) {
                 QString c = colors[i];
                 QString str;
                 str.sprintf("%4d", i + 1);
                 m_colorNames << (str + "   " + c);

                 QStringList duet = c.split(' ');
                 m_firstColor << duet[0];
                 m_secondColor << duet[1];
             }

             setAttribute(Qt::WA_OpaquePaintEvent, true);
             setAttribute(Qt::WA_NoSystemBackground, true);

             setMouseTracking(true);
             Flickable::setAcceptMouseClick(this);
         }

     protected:
         // reimplement from Flickable
         virtual QPoint scrollOffset() const {
             return QPoint(0, m_offset);
         }

         // reimplement from Flickable
         virtual void setScrollOffset(const QPoint &offset) {
             int yy = offset.y();
             if (yy != m_offset) {
                 m_offset = qBound(0, yy, m_height * m_colorNames.count() - height());
                 update();
             }
         }

     protected:
         void paintEvent(QPaintEvent *event) {
             QPainter p(this);
             p.fillRect(event->rect(), Qt::white);
             int start = m_offset / m_height;
             int y = start * m_height - m_offset;
             if (m_offset <= 0) {
                 start = 0;
                 y = -m_offset;
             }
             int end = start + height() / m_height + 1;
             if (end > m_colorNames.count() - 1)
                 end = m_colorNames.count() - 1;
             for (int i = start; i <= end; ++i, y += m_height) {

                 p.setBrush(Qt::NoBrush);
                 p.setPen(Qt::black);
                 if (i == m_highlight) {
                     p.fillRect(0, y, width(), m_height, QColor(0, 64, 128));
                     p.setPen(Qt::white);
                 }
                 if (i == m_selected) {
                     p.fillRect(0, y, width(), m_height, QColor(0, 128, 240));
                     p.setPen(Qt::white);
                 }

                 p.drawText(m_height + 2, y, width(), m_height, Qt::AlignVCenter, m_colorNames[i]);

                 p.setPen(Qt::NoPen);
                 p.setBrush(m_firstColor[i]);
                 p.drawRect(1, y + 1, m_height - 2, m_height - 2);
                 p.setBrush(m_secondColor[i]);
                 p.drawRect(5, y + 5, m_height - 11, m_height - 11);
             }
             p.end();
         }

         void keyReleaseEvent(QKeyEvent *event) {
             if (event->key() == Qt::Key_Down) {
                 m_offset += 20;
                 event->accept();
                 update();
                 return;
             }
             if (event->key() == Qt::Key_Up) {
                 m_offset -= 20;
                 event->accept();
                 update();
                 return;
             }
         }

         void mousePressEvent(QMouseEvent *event) {
             Flickable::handleMousePress(event);
             if (event->isAccepted())
                 return;

             if (event->button() == Qt::LeftButton) {
                 int y = event->pos().y() + m_offset;
                 int i = y / m_height;
                 if (i != m_highlight) {
                     m_highlight = i;
                     m_selected = -1;
                     update();
                 }
                 event->accept();
             }
         }

         void mouseMoveEvent(QMouseEvent *event) {
             Flickable::handleMouseMove(event);
         }

         void mouseReleaseEvent(QMouseEvent *event) {
             Flickable::handleMouseRelease(event);
             if (event->isAccepted())
                 return;

             if (event->button() == Qt::LeftButton) {
                 m_selected = m_highlight;
                 event->accept();
                 update();
             }
         }

     private:
         int m_offset;
         int m_height;
         int m_highlight;
         int m_selected;
         QStringList m_colorNames;
         QList<QColor> m_firstColor;
         QList<QColor> m_secondColor;
     };

     #include "main.moc"

     int main(int argc, char *argv[])
     {
         QApplication app(argc, argv);

         ColorList list;
         list.setWindowTitle("Kinetic Scrolling");
     #if defined(Q_OS_SYMBIAN) || defined(Q_OS_WINCE_WM)
         list.showMaximized();
     #else
         list.resize(320, 320);
         list.show();
     #endif

         return app.exec();
     }