BoxBlurFilter.java

package com.jpii.navalbattle.pavo;

import java.awt.*;
import java.awt.image.*;
import java.awt.geom.*;

public class BoxBlurFilter extends AbstractBufferedImageOp {

	private int hRadius;
	private int vRadius;
	private int iterations = 1;
	
    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;
    }
    
    /**
	 * Clamp a value to an interval.
	 * @param a the lower clamp threshold
	 * @param b the upper clamp threshold
	 * @param x the input parameter
	 * @return the clamped value
	 */
	public static float clamp(float x, float a, float b) {
		return (x < a) ? a : (x > b) ? b : x;
	}

	/**
	 * Clamp a value to an interval.
	 * @param a the lower clamp threshold
	 * @param b the upper clamp threshold
	 * @param x the input parameter
	 * @return the clamped value
	 */
	public static int clamp(int x, int a, int b) {
		return (x < a) ? a : (x > b) ? b : x;
	}

    public 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)];
                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];
                
                tr += ((rgb1 & 0xff0000)-(rgb2 & 0xff0000)) >> 16;
                tg += ((rgb1 & 0xff00)-(rgb2 & 0xff00)) >> 8;
                tb += (rgb1 & 0xff)-(rgb2 & 0xff);
                outIndex += height;
            }
            inIndex += width;
        }
    }
        
	public void setHRadius(int hRadius) {
		this.hRadius = hRadius;
	}
	
	public int getHRadius() {
		return hRadius;
	}
	
	public void setVRadius(int vRadius) {
		this.vRadius = vRadius;
	}
	
	public int getVRadius() {
		return vRadius;
	}
	
	public void setRadius(int radius) {
		this.hRadius = this.vRadius = radius;
	}
	
	public int getRadius() {
		return hRadius;
	}
	
	public void setIterations(int iterations) {
		this.iterations = iterations;
	}
	
	public int getIterations() {
		return iterations;
	}
	
	public String toString() {
		return "Blur/Box Blur...";
	}
}

abstract class AbstractBufferedImageOp implements BufferedImageOp {

    public BufferedImage createCompatibleDestImage(BufferedImage src, ColorModel dstCM) {
        if ( dstCM == null )
            dstCM = src.getColorModel();
        return new BufferedImage(dstCM, dstCM.createCompatibleWritableRaster(src.getWidth(), src.getHeight()), dstCM.isAlphaPremultiplied(), null);
    }
    
    public Rectangle2D getBounds2D( BufferedImage src ) {
        return new Rectangle(0, 0, src.getWidth(), src.getHeight());
    }
    
    public Point2D getPoint2D( Point2D srcPt, Point2D dstPt ) {
        if ( dstPt == null )
            dstPt = new Point2D.Double();
        dstPt.setLocation( srcPt.getX(), srcPt.getY() );
        return dstPt;
    }

    public RenderingHints getRenderingHints() {
        return null;
    }

	/**
	 * A convenience method for getting ARGB pixels from an image. This tries to avoid the performance
	 * penalty of BufferedImage.getRGB not managing the image.
	 */
	public int[] getRGB( BufferedImage image, int x, int y, int width, int height, int[] pixels ) {
		int type = image.getType();
		if ( type == BufferedImage.TYPE_INT_ARGB || type == BufferedImage.TYPE_INT_RGB )
			return (int [])image.getRaster().getDataElements( x, y, width, height, pixels );
		else
			return image.getRGB( x, y, width, height, pixels, 0, width );
    }

	/**
	 * A convenience method for setting ARGB pixels in an image. This tries to avoid the performance
	 * penalty of BufferedImage.setRGB not managing the image.
	 */
	public void setRGB( BufferedImage image, int x, int y, int width, int height, int[] pixels ) {
		int type = image.getType();
		if ( type == BufferedImage.TYPE_INT_ARGB || type == BufferedImage.TYPE_INT_RGB )
			image.getRaster().setDataElements( x, y, width, height, pixels );
		else
			image.setRGB( x, y, width, height, pixels, 0, width );
    }
}