Qt Reference Documentation

# button.cpp Example File

demos/mobile/qcamera/button.cpp

     /****************************************************************************
     **
     ** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
     ** All rights reserved.
     ** Contact: Nokia Corporation (qt-info@nokia.com)
     **
     ** This file is part of the demonstration applications 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 Nokia Corporation and its Subsidiary(-ies) 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 "button.h"
     #include <QMouseEvent>
     #include <QPainter>
     #include <QTimer>

     Button::Button(QWidget *parent, Qt::WindowFlags f) :
         QLabel(parent, f)
     {
         m_downPixmap = 0;
         m_disabled = false;
     }

     Button::~Button()
     {
     }

     void Button::disableBtn(bool b)
     {
         m_disabled = b;
         if (m_disabled) {
             setPixmap(m_downPixmap);
         } else {
             setPixmap(m_upPixmap);
         }
     }

     void Button::mousePressEvent(QMouseEvent *event)
     {
         if (!m_disabled) {
             event->accept();
             setPixmap(m_downPixmap);
             repaint();
             // Lift button back to up after 300ms
             QTimer::singleShot(300, this, SLOT(backToUp()));
         }
     }

     void Button::backToUp()
     {
         setPixmap(m_upPixmap);
         repaint();
         emit pressed();
     }

     void Button::setPixmap(const QPixmap& p)
     {
         // Set up and down picture for the button
         // Set pixmap
         if (!p.isNull())
             QLabel::setPixmap(p);

         // Make down pixmap if it does not exists
         if (m_downPixmap.isNull()) {
             // Store up pixmap
             m_upPixmap = *pixmap();

             // Create down pixmap
             // Make m_downPixmap as a transparent m_upPixmap
             QPixmap transparent(m_upPixmap.size());
             transparent.fill(Qt::transparent);
             QPainter painter(&transparent);
             painter.setCompositionMode(QPainter::CompositionMode_Source);
             painter.drawPixmap(0, 0, m_upPixmap);
             painter.setCompositionMode(QPainter::CompositionMode_DestinationIn);
             painter.fillRect(transparent.rect(), QColor(0, 0, 0, 150));
             painter.end();
             m_downPixmap = transparent;
         }

     }