doc/src/snippets/alphachannel.cpp
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     1 /****************************************************************************
       
     2 **
       
     3 ** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
       
     4 ** All rights reserved.
       
     5 ** Contact: Nokia Corporation (qt-info@nokia.com)
       
     6 **
       
     7 ** This file is part of the documentation of the Qt Toolkit.
       
     8 **
       
     9 ** $QT_BEGIN_LICENSE:LGPL$
       
    10 ** No Commercial Usage
       
    11 ** This file contains pre-release code and may not be distributed.
       
    12 ** You may use this file in accordance with the terms and conditions
       
    13 ** contained in the Technology Preview License Agreement accompanying
       
    14 ** this package.
       
    15 **
       
    16 ** GNU Lesser General Public License Usage
       
    17 ** Alternatively, this file may be used under the terms of the GNU Lesser
       
    18 ** General Public License version 2.1 as published by the Free Software
       
    19 ** Foundation and appearing in the file LICENSE.LGPL included in the
       
    20 ** packaging of this file.  Please review the following information to
       
    21 ** ensure the GNU Lesser General Public License version 2.1 requirements
       
    22 ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
       
    23 **
       
    24 ** In addition, as a special exception, Nokia gives you certain additional
       
    25 ** rights.  These rights are described in the Nokia Qt LGPL Exception
       
    26 ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
       
    27 **
       
    28 ** If you have questions regarding the use of this file, please contact
       
    29 ** Nokia at qt-info@nokia.com.
       
    30 **
       
    31 **
       
    32 **
       
    33 **
       
    34 **
       
    35 **
       
    36 **
       
    37 **
       
    38 ** $QT_END_LICENSE$
       
    39 **
       
    40 ****************************************************************************/
       
    41 
       
    42 #include <qapplication.h>
       
    43 #include <qlabel.h>
       
    44 #include <qpixmap.h>
       
    45 #include <qprinter.h>
       
    46 #include <qpainter.h>
       
    47 #include <qfile.h>
       
    48 #include <qdir.h>
       
    49 #include <qfileinfo.h>
       
    50 #include <QtGui>
       
    51 #include <QtCore>
       
    52 
       
    53 class MyClass : public QWidget
       
    54 {
       
    55 public:
       
    56      MyClass(QWidget *parent = 0) : QWidget(parent) { }
       
    57 
       
    58 protected:
       
    59      void paintEvent(QPaintEvent *e)
       
    60      {
       
    61         /*QRadialGradient rg(50, 50, 50, 50, 50);
       
    62          rg.setColorAt(0, QColor::fromRgbF(1, 0, 0, 1));
       
    63          rg.setColorAt(1, QColor::fromRgbF(0, 0, 0, 0));
       
    64          QPainter pmp(&pm);
       
    65          pmp.fillRect(0, 0, 100, 100, rg);
       
    66          pmp.end();*/
       
    67 
       
    68 	createImage();
       
    69 
       
    70 	QPainter p(this);
       
    71 	p.fillRect(rect(), Qt::white);
       
    72 
       
    73 	p.drawPixmap(0, 0, pixmap);
       
    74 
       
    75 	p.drawPixmap(100, 0, channelImage);
       
    76      }
       
    77 
       
    78     void createImage()
       
    79     {
       
    80 //! [0]
       
    81 	pixmap = QPixmap(100, 100);
       
    82 	pixmap.fill(Qt::transparent);
       
    83 
       
    84 	QRadialGradient gradient(50, 50, 50, 50, 50);
       
    85 	gradient.setColorAt(0, QColor::fromRgbF(1, 0, 0, 1));
       
    86 	gradient.setColorAt(1, QColor::fromRgbF(0, 0, 0, 0));
       
    87 	QPainter painter(&pixmap);
       
    88 	painter.fillRect(0, 0, 100, 100, gradient);
       
    89 
       
    90 	channelImage = pixmap.alphaChannel();
       
    91 	update();
       
    92 //! [0]
       
    93     }
       
    94 
       
    95     QPixmap channelImage, pixmap;
       
    96     QSize sizeHint() const { return QSize(500, 500); }
       
    97 };
       
    98 
       
    99 int main(int argc, char **argv)
       
   100 {
       
   101      QApplication app(argc, argv);
       
   102 
       
   103      MyClass cl;
       
   104      cl.show();
       
   105      QObject::connect(&app, SIGNAL(lastWindowClosed()), &app, SLOT(quit()));
       
   106 
       
   107      int ret = app.exec();
       
   108      return ret;
       
   109 }