// from http://www.jhlabs.com/ip/blurring.html

/*
Copyright 2006 Jerry Huxtable

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

sclass BoxBlurFilter extends AbstractBufferedImageOp implements IF1<BufferedImage> {
  int hRadius;
  int vRadius;
  int iterations = 1;
  
  *() {}
  *(int radius) { hRadius = vRadius = radius; }
  *(int *hRadius, int *vRadius) {}
  
  public BufferedImage get(BufferedImage src) {
    ret filter(src, null);
  }
  
  public BufferedImage filter(BufferedImage src, BufferedImage dst) {
        int width = src.getWidth();
        int height = src.getHeight();

        if ( dst == null )
            dst = createCompatibleDestImage( src, null );

        int[] inPixels = new int[width*height];
        int[] outPixels = new int[width*height];
        getRGB( src, 0, 0, width, height, inPixels );

        for (int i = 0; i < iterations; i++ ) {
            blur( inPixels, outPixels, width, height, hRadius );
            blur( outPixels, inPixels, height, width, vRadius );
        }

        setRGB( dst, 0, 0, width, height, inPixels );
        return dst;
    }

    static void blur( int[] in, int[] out, int width, int height, int radius ) {
        int widthMinus1 = width-1;
        int tableSize = 2*radius+1;
        int divide[] = new int[256*tableSize];

        for ( int i = 0; i < 256*tableSize; i++ )
            divide[i] = i/tableSize;

        int inIndex = 0;
        
        for ( int y = 0; y < height; y++ ) {
            int outIndex = y;
            int ta = 0, tr = 0, tg = 0, tb = 0;

            for ( int i = -radius; i <= radius; i++ ) {
                int rgb = in[inIndex + clamp(i, 0, width-1)];
                ta += (rgb >> 24) & 0xff;
                tr += (rgb >> 16) & 0xff;
                tg += (rgb >> 8) & 0xff;
                tb += rgb & 0xff;
            }

            for ( int x = 0; x < width; x++ ) {
                out[ outIndex ] = (divide[ta] << 24) | (divide[tr] << 16) | (divide[tg] << 8) | divide[tb];

                int i1 = x+radius+1;
                if ( i1 > widthMinus1 )
                    i1 = widthMinus1;
                int i2 = x-radius;
                if ( i2 < 0 )
                    i2 = 0;
                int rgb1 = in[inIndex+i1];
                int rgb2 = in[inIndex+i2];
                
                ta += ((rgb1 >> 24) & 0xff)-((rgb2 >> 24) & 0xff);
                tr += ((rgb1 & 0xff0000)-(rgb2 & 0xff0000)) >> 16;
                tg += ((rgb1 & 0xff00)-(rgb2 & 0xff00)) >> 8;
                tb += (rgb1 & 0xff)-(rgb2 & 0xff);
                outIndex += height;
            }
            inIndex += width;
        }
    }
}