/****************************************************************************
 **
 ** Copyright (C) 2006-2007 Trolltech ASA. All rights reserved.
 **
 ** This file is part of the example classes of the Qt Toolkit.
 **
 ** This file may be used under the terms of the GNU General Public
 ** License version 2.0 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 GNU
 ** General Public Licensing requirements will be met:
 ** http://trolltech.com/products/qt/licenses/licensing/opensource/
 **
 ** If you are unsure which license is appropriate for your use, please
 ** review the following information:
 ** http://trolltech.com/products/qt/licenses/licensing/licensingoverview
 ** or contact the sales department at sales@trolltech.com.
 **
 ** In addition, as a special exception, Trolltech gives you certain
 ** additional rights. These rights are described in the Trolltech GPL
 ** Exception version 1.0, which can be found at
 ** http://www.trolltech.com/products/qt/gplexception/ and in the file
 ** GPL_EXCEPTION.txt in this package.
 **
 ** In addition, as a special exception, Trolltech, as the sole copyright
 ** holder for Qt Designer, grants users of the Qt/Eclipse Integration
 ** plug-in the right for the Qt/Eclipse Integration to link to
 ** functionality provided by Qt Designer and its related libraries.
 **
 ** Trolltech reserves all rights not expressly granted herein.
 **
 ** Trolltech ASA (c) 2007
 **
 ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 **
 ****************************************************************************/
 
 #include <qimage.h>
 #include <qcolor.h>
 
 static inline int blendComponent( int v, int av, int s, int as )
 {
     return as*s + av*v -(av*as*s)/255;
 }
 
 static inline QRgb blendShade( QRgb v, QRgb s )
 {
     //shadow image is already reduced and blurred
     int as = qAlpha(s);
     int av = qAlpha(v);
     if ( as == 0 || av == 255 )
         return v;
 
     int a = as + av -(as*av)/255;
 
     int r = blendComponent( qRed(v),av, qRed(s), as)/a;
     int g = blendComponent( qGreen(v),av, qGreen(s), as)/a;
     int b = blendComponent( qBlue(v),av, qBlue(s), as)/a;
 
     return qRgba(r,g,b,a);
 }
 
 int main( int*, char**)
 {
     QImage image( "out.png" );
     image.convertDepth( 32 );
     QImage shade( "outshade.png" );
     shade.convertDepth( 32 );
     int dx = 10;
     int dy = 5;
 
     int w = image.width();
     int h = image.height();
 
     QImage img( w+dx, h+dy, 32 );
     img.setAlphaBuffer( TRUE );
 
     for ( int y = 0; y < h+dy; y++ ) {
         for ( int x = 0; x < w+dx; x++ ) {
             QRgb sh =  (x<dx||y<dy) ? 0 : shade.pixel( x-dx, y-dy );
             QRgb pixel = (x<w&y<h) ? image.pixel( x, y ) : 0;
             img.setPixel( x, y, blendShade( pixel, sh ) );
         }
     }
     img.save("blend.png", "PNG" );
 }