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#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" );

}