doc/src/snippets/alphachannel.cpp
author eckhart.koppen@nokia.com
Wed, 31 Mar 2010 11:06:36 +0300
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/****************************************************************************
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**
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** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
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** All rights reserved.
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** Contact: Nokia Corporation (qt-info@nokia.com)
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**
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** This file is part of the documentation of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:LGPL$
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** No Commercial Usage
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** This file contains pre-release code and may not be distributed.
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** You may use this file in accordance with the terms and conditions
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** contained in the Technology Preview License Agreement accompanying
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** this package.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 2.1 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL included in the
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** packaging of this file.  Please review the following information to
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** ensure the GNU Lesser General Public License version 2.1 requirements
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** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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**
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** In addition, as a special exception, Nokia gives you certain additional
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** rights.  These rights are described in the Nokia Qt LGPL Exception
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** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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**
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** If you have questions regarding the use of this file, please contact
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** Nokia at qt-info@nokia.com.
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**
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**
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**
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**
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**
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**
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**
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#include <qapplication.h>
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#include <qlabel.h>
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#include <qpixmap.h>
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#include <qprinter.h>
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#include <qpainter.h>
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#include <qfile.h>
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#include <qdir.h>
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#include <qfileinfo.h>
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#include <QtGui>
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#include <QtCore>
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class MyClass : public QWidget
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{
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public:
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     MyClass(QWidget *parent = 0) : QWidget(parent) { }
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protected:
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     void paintEvent(QPaintEvent *e)
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     {
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        /*QRadialGradient rg(50, 50, 50, 50, 50);
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         rg.setColorAt(0, QColor::fromRgbF(1, 0, 0, 1));
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         rg.setColorAt(1, QColor::fromRgbF(0, 0, 0, 0));
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         QPainter pmp(&pm);
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         pmp.fillRect(0, 0, 100, 100, rg);
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         pmp.end();*/
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	createImage();
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	QPainter p(this);
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	p.fillRect(rect(), Qt::white);
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	p.drawPixmap(0, 0, pixmap);
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	p.drawPixmap(100, 0, channelImage);
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     }
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    void createImage()
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    {
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//! [0]
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	pixmap = QPixmap(100, 100);
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	pixmap.fill(Qt::transparent);
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	QRadialGradient gradient(50, 50, 50, 50, 50);
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	gradient.setColorAt(0, QColor::fromRgbF(1, 0, 0, 1));
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	gradient.setColorAt(1, QColor::fromRgbF(0, 0, 0, 0));
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	QPainter painter(&pixmap);
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	painter.fillRect(0, 0, 100, 100, gradient);
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	channelImage = pixmap.alphaChannel();
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	update();
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//! [0]
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    }
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    QPixmap channelImage, pixmap;
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    QSize sizeHint() const { return QSize(500, 500); }
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};
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int main(int argc, char **argv)
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{
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     QApplication app(argc, argv);
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     MyClass cl;
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     cl.show();
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     QObject::connect(&app, SIGNAL(lastWindowClosed()), &app, SLOT(quit()));
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     int ret = app.exec();
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     return ret;
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}