/*
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.*;

/**
 * A filter which allows levels adjustment on an image.
 */
public class LevelsFilter extends WholeImageFilter {

	private int[][] lut;
    private float lowLevel = 0;
    private float highLevel = 1;
    private float lowOutputLevel = 0;
    private float highOutputLevel = 1;

	public LevelsFilter() {
	}

    public void setLowLevel( float lowLevel ) {
        this.lowLevel = lowLevel;
    }
    
    public float getLowLevel() {
        return lowLevel;
    }
    
    public void setHighLevel( float highLevel ) {
        this.highLevel = highLevel;
    }
    
    public float getHighLevel() {
        return highLevel;
    }
    
    public void setLowOutputLevel( float lowOutputLevel ) {
        this.lowOutputLevel = lowOutputLevel;
    }
    
    public float getLowOutputLevel() {
        return lowOutputLevel;
    }
    
    public void setHighOutputLevel( float highOutputLevel ) {
        this.highOutputLevel = highOutputLevel;
    }
    
    public float getHighOutputLevel() {
        return highOutputLevel;
    }
    
	protected int[] filterPixels( int width, int height, int[] inPixels, Rectangle transformedSpace ) {
		Histogram histogram = new Histogram(inPixels, width, height, 0, width);

		int i, j;

		if (histogram.getNumSamples() > 0) {
			float scale = 255.0f / histogram.getNumSamples();
			lut = new int[3][256];

            float low = lowLevel * 255;
            float high = highLevel * 255;
            if ( low == high )
                high++;
			for (i = 0; i < 3; i++) {
				for (j = 0; j < 256; j++)
					lut[i][j] = PixelUtils.clamp( (int)(255 * (lowOutputLevel + (highOutputLevel-lowOutputLevel) * (j-low)/(high-low))) );
			}
		} else
			lut = null;

		i = 0;
		for (int y = 0; y < height; y++)
			for (int x = 0; x < width; x++) {
				inPixels[i] = filterRGB(x, y, inPixels[i]);
				i++;
			}
		lut = null;
		
		return inPixels;
	}

	public int filterRGB(int x, int y, int rgb) {
		if (lut != null) {
			int a = rgb & 0xff000000;
			int r = lut[Histogram.RED][(rgb >> 16) & 0xff];
			int g = lut[Histogram.GREEN][(rgb >> 8) & 0xff];
			int b = lut[Histogram.BLUE][rgb & 0xff];

			return a | (r << 16) | (g << 8) | b;
		}
		return rgb;
	}

	public String toString() {
		return "Colors/Levels...";
	}
}
