JavaScript实现的图像模糊算法代码分享(2)

    for ( x = 0; x < width; x++ )
    {
        g_in_sum = b_in_sum = a_in_sum = r_in_sum = g_sum = b_sum = a_sum = r_sum = 0;

        yi = x << 2;
        r_out_sum = radiusPlus1 * ( pr = pixels[yi]);
        g_out_sum = radiusPlus1 * ( pg = pixels[yi+1]);
        b_out_sum = radiusPlus1 * ( pb = pixels[yi+2]);
        a_out_sum = radiusPlus1 * ( pa = pixels[yi+3]);

        r_sum += sumFactor * pr;
        g_sum += sumFactor * pg;
        b_sum += sumFactor * pb;
        a_sum += sumFactor * pa;

        stack = stackStart;

        for( i = 0; i < radiusPlus1; i++ )
        {
            stack.r = pr;
            stack.g = pg;
            stack.b = pb;
            stack.a = pa;
            stack = stack.next;
        }

        yp = width;

        for( i = 1; i <= radius; i++ )
        {
            yi = ( yp + x ) << 2;

            r_sum += ( stack.r = ( pr = pixels[yi])) * ( rbs = radiusPlus1 - i );
            g_sum += ( stack.g = ( pg = pixels[yi+1])) * rbs;
            b_sum += ( stack.b = ( pb = pixels[yi+2])) * rbs;
            a_sum += ( stack.a = ( pa = pixels[yi+3])) * rbs;

            r_in_sum += pr;
            g_in_sum += pg;
            b_in_sum += pb;
            a_in_sum += pa;

            stack = stack.next;

            if( i < heightMinus1 )
            {
                yp += width;
            }
        }

        yi = x;
        stackIn = stackStart;
        stackOut = stackEnd;
        for ( y = 0; y < height; y++ )
        {
            p = yi << 2;
            pixels[p+3] = pa = (a_sum * mul_sum) >> shg_sum;
            if ( pa > 0 )
            {
                pa = 255 / pa;
                pixels[p]   = ((r_sum * mul_sum) >> shg_sum ) * pa;
                pixels[p+1] = ((g_sum * mul_sum) >> shg_sum ) * pa;
                pixels[p+2] = ((b_sum * mul_sum) >> shg_sum ) * pa;
            } else {
                pixels[p] = pixels[p+1] = pixels[p+2] = 0;
            }

            r_sum -= r_out_sum;
            g_sum -= g_out_sum;
            b_sum -= b_out_sum;
            a_sum -= a_out_sum;

            r_out_sum -= stackIn.r;
            g_out_sum -= stackIn.g;
            b_out_sum -= stackIn.b;
            a_out_sum -= stackIn.a;

            p = ( x + (( ( p = y + radiusPlus1) < heightMinus1 ? p : heightMinus1 ) * width )) << 2;

            r_sum += ( r_in_sum += ( stackIn.r = pixels[p]));
            g_sum += ( g_in_sum += ( stackIn.g = pixels[p+1]));
            b_sum += ( b_in_sum += ( stackIn.b = pixels[p+2]));
            a_sum += ( a_in_sum += ( stackIn.a = pixels[p+3]));

            stackIn = stackIn.next;

            r_out_sum += ( pr = stackOut.r );
            g_out_sum += ( pg = stackOut.g );
            b_out_sum += ( pb = stackOut.b );
            a_out_sum += ( pa = stackOut.a );

            r_in_sum -= pr;
            g_in_sum -= pg;
            b_in_sum -= pb;
            a_in_sum -= pa;

            stackOut = stackOut.next;

            yi += width;
        }
    }

    context.putImageData( imageData, top_x, top_y );

}