/*
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.
*/

package com.jhlabs.image;

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

/**
 * Given a binary image, this filter performs binary erosion, setting all removed pixels to the given 'new' color.
 */
public class ErodeFilter extends BinaryFilter {

	private int threshold = 2;

	public ErodeFilter() {
		newColor = 0xffffffff;
	}

	/**
	 * Set the threshold - the number of neighbouring pixels for dilation to occur.
	 * @param threshold the new threshold
     * @see #getThreshold
	 */
	public void setThreshold(int threshold) {
		this.threshold = threshold;
	}
	
	/**
	 * Return the threshold - the number of neighbouring pixels for dilation to occur.
	 * @return the current threshold
     * @see #setThreshold
	 */
	public int getThreshold() {
		return threshold;
	}
	
	protected int[] filterPixels( int width, int height, int[] inPixels, Rectangle transformedSpace ) {
		int[] outPixels = new int[width * height];

		for (int i = 0; i < iterations; i++) {
			int index = 0;

			if (i > 0) {
				int[] t = inPixels;
				inPixels = outPixels;
				outPixels = t;
			}
			for (int y = 0; y < height; y++) {
				for (int x = 0; x < width; x++) {
					int pixel = inPixels[y*width+x];
					if (blackFunction.isBlack(pixel)) {
						int neighbours = 0;

						for (int dy = -1; dy <= 1; dy++) {
							int iy = y+dy;
							int ioffset;
							if (0 <= iy && iy < height) {
								ioffset = iy*width;
								for (int dx = -1; dx <= 1; dx++) {
									int ix = x+dx;
									if (!(dy == 0 && dx == 0) && 0 <= ix && ix < width) {
										int rgb = inPixels[ioffset+ix];
										if (!blackFunction.isBlack(rgb))
											neighbours++;
									}
								}
							}
						}
						
						if (neighbours >= threshold) {
							if (colormap != null)
								pixel = colormap.getColor((float)i/iterations);
							else
								pixel = newColor;
						}
					}
					outPixels[index++] = pixel;
				}
			}
		}

		return outPixels;
	}

	public String toString() {
		return "Binary/Erode...";
	}

}

