/*
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 org.meteoinfo.image.filter;

import java.awt.*;

/**
 * A filter which draws contours on an image at given brightness levels.
 */
public class ContourFilter extends WholeImageFilter {

    private float levels = 5;
    private float scale = 1;
    private float offset = 0;
    private int contourColor = 0xff000000;

    public ContourFilter() {
    }

    public void setLevels(float levels) {
        this.levels = levels;
    }

    public float getLevels() {
        return levels;
    }

    /**
     * Specifies the scale of the contours.
     *
     * @param scale the scale of the contours.
     * min-value 0
     * max-value 1
     * @see #getScale
     */
    public void setScale(float scale) {
        this.scale = scale;
    }

    /**
     * Returns the scale of the contours.
     *
     * @return the scale of the contours.
     * @see #setScale
     */
    public float getScale() {
        return scale;
    }

    public void setOffset(float offset) {
        this.offset = offset;
    }

    public float getOffset() {
        return offset;
    }

    public void setContourColor(int contourColor) {
        this.contourColor = contourColor;
    }

    public int getContourColor() {
        return contourColor;
    }

    protected int[] filterPixels(int width, int height, int[] inPixels, Rectangle transformedSpace) {
        int index = 0;
        short[][] r = new short[3][width];
        int[] outPixels = new int[width * height];

        short[] table = new short[256];
        int offsetl = (int) (offset * 256 / levels);
        for (int i = 0; i < 256; i++) {
            table[i] = (short) PixelUtils.clamp((int) (255 * Math.floor(levels * (i + offsetl) / 256) / (levels - 1) - offsetl));
        }

        for (int x = 0; x < width; x++) {
            int rgb = inPixels[x];
            r[1][x] = (short) PixelUtils.brightness(rgb);
        }
        for (int y = 0; y < height; y++) {
            boolean yIn = y > 0 && y < height - 1;
            int nextRowIndex = index + width;
            if (y < height - 1) {
                for (int x = 0; x < width; x++) {
                    int rgb = inPixels[nextRowIndex++];
                    r[2][x] = (short) PixelUtils.brightness(rgb);
                }
            }
            for (int x = 0; x < width; x++) {
                boolean xIn = x > 0 && x < width - 1;
                int w = x - 1;
                int e = x + 1;
                int v = 0;

                if (yIn && xIn) {
                    short nwb = r[0][w];
                    short neb = r[0][x];
                    short swb = r[1][w];
                    short seb = r[1][x];
                    short nw = table[nwb];
                    short ne = table[neb];
                    short sw = table[swb];
                    short se = table[seb];

                    if (nw != ne || nw != sw || ne != se || sw != se) {
                        v = (int) (scale * (Math.abs(nwb - neb) + Math.abs(nwb - swb) + Math.abs(neb - seb) + Math.abs(swb - seb)));
//						v /= 255;
                        if (v > 255) {
                            v = 255;
                        }
                    }
                }

                if (v != 0) {
                    outPixels[index] = PixelUtils.combinePixels(inPixels[index], contourColor, PixelUtils.NORMAL, v);
                } //					outPixels[index] = PixelUtils.combinePixels( (contourColor & 0xff)|(v << 24), inPixels[index], PixelUtils.NORMAL );
                else {
                    outPixels[index] = inPixels[index];
                }
                index++;
            }
            short[] t;
            t = r[0];
            r[0] = r[1];
            r[1] = r[2];
            r[2] = t;
        }

        return outPixels;
    }

    public String toString() {
        return "Stylize/Contour...";
    }

}
