Qt 4.3: makeimg.cpp Example File (graphicsview/portedcanvas/makeimg.cpp)

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# makeimg.cpp Example File
graphicsview/portedcanvas/makeimg.cpp

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     #include <qimage.h>
     #include <qcolor.h>

     static inline int blendComponent( int v, int av, int s, int as )
     {
         //shadow gets a color inversely proportional to the
         //alpha value
         s = (s*(255-as))/255;
         //then do standard blending
         return as*s + av*v -(av*as*s)/255;
     }

     static inline QRgb blendShade( QRgb v, QRgb s )
     {
         //pick a number: shadow is 1/3 of object
         int as = qAlpha(s)/3;
         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 *img;

         img = new QImage( "in.png" );
         int w,h;
         int y;
         img->setAlphaBuffer( TRUE );
         *img = img->convertDepth( 32 );
         w = img->width();
         h = img->height();
     #if 0
         for ( y = 0; y < h; y ++ ) {
             uint *line = (uint*)img->scanLine( y );
             for ( int x = 0; x < w; x++ ) {
                 uint pixel = line[x];
                 int r = qRed(pixel);
                 int g = qGreen(pixel);
                 int b = qBlue(pixel);
                 int min = QMIN( r, QMIN( g, b ) );
                 int max = QMAX( r, QMAX( g, b ) );
                 r -= min;
                 g -= min;
                 b -= min;
                 if ( max !=min ) {
                     r = (r*255)/(max-min);
                     g = (g*255)/(max-min);
                     b = (b*255)/(max-min);
                 }
                 int a = 255-min;
                 a -=  (max-min)/3; //hack more transparency for colors.
                 line[x] = qRgba( r, g, b, a );
             }
         }
     #endif
         *img = img->smoothScale( w/2, h/2 );

         qDebug( "saving out.png");
         img->save( "out.png", "PNG" );

         w = img->width();
         h = img->height();

         QImage *img2 = new QImage( w, h, 32 );
         img2->setAlphaBuffer( TRUE );
         for ( y = 0; y < h; y++ ) {
             for ( int x = 0; x < w; x++ ) {
                 QRgb shader = img->pixel( x, y );

                 int as = qAlpha(shader)/3;

                 int r = (qRed(shader)*(255-as))/255;
                 int g = (qGreen(shader)*(255-as))/255;
                 int b = (qBlue(shader)*(255-as))/255;

                 img2->setPixel( x, y, qRgba(r,g,b,as) );
             }
         }

         img2->save( "outshade.png", "PNG" );

     }