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

        /****************************************************************************
        **
        ** Copyright (C) 2006-2006 Trolltech ASA. All rights reserved.
        **
        ** This file is part of the example classes of the Qt Toolkit.
        **
        ** Licensees holding valid Qt Preview licenses may use this file in
        ** accordance with the Qt Preview License Agreement provided with the
        ** Software.
        **
        ** See http://www.trolltech.com/pricing.html or email sales@trolltech.com for
        ** information about Qt Commercial License Agreements.
        **
        ** Contact info@trolltech.com if any conditions of this licensing are
        ** not clear to you.
        **
        ** 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 )
        {
            //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" );

        }