examples/graphicsview/portedcanvas/blendshadow.cpp
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     1 /****************************************************************************
       
     2 **
       
     3 ** Copyright (C) 2009 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 examples 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.
       
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    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
       
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    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 <qimage.h>
       
    43 #include <qcolor.h>
       
    44 
       
    45 static inline int blendComponent( int v, int av, int s, int as )
       
    46 {
       
    47     return as*s + av*v -(av*as*s)/255;  
       
    48 }
       
    49     
       
    50 static inline QRgb blendShade( QRgb v, QRgb s )
       
    51 {
       
    52     //shadow image is already reduced and blurred
       
    53     int as = qAlpha(s); 
       
    54     int av = qAlpha(v);
       
    55     if ( as == 0 || av == 255 )
       
    56 	return v;
       
    57 
       
    58     int a = as + av -(as*av)/255;
       
    59     
       
    60     int r = blendComponent( qRed(v),av, qRed(s), as)/a;
       
    61     int g = blendComponent( qGreen(v),av, qGreen(s), as)/a;
       
    62     int b = blendComponent( qBlue(v),av, qBlue(s), as)/a;
       
    63 
       
    64     return qRgba(r,g,b,a);
       
    65 }
       
    66 
       
    67  
       
    68 
       
    69 int main( int*, char**)
       
    70 {
       
    71     QImage image( "out.png" );
       
    72     image.convertDepth( 32 );
       
    73     QImage shade( "outshade.png" );
       
    74     shade.convertDepth( 32 );
       
    75     int dx = 10;
       
    76     int dy = 5;
       
    77 	
       
    78     int w = image.width();
       
    79     int h = image.height();
       
    80 	
       
    81     QImage img( w+dx, h+dy, 32 );
       
    82     img.setAlphaBuffer( TRUE );
       
    83 
       
    84     for ( int y = 0; y < h+dy; y++ ) {
       
    85 	for ( int x = 0; x < w+dx; x++ ) {
       
    86 	    QRgb sh =  (x<dx||y<dy) ? 0 : shade.pixel( x-dx, y-dy );
       
    87 	    QRgb pixel = (x<w&y<h) ? image.pixel( x, y ) : 0;
       
    88 	    img.setPixel( x, y, blendShade( pixel, sh ) ); 
       
    89 	}
       
    90     }
       
    91     img.save("blend.png", "PNG" );
       
    92 }
       
    93 
       
    94