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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" );

    }