button.cpp Example File

 /****************************************************************************
 **
 ** 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;
     }

 }