/*
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.image.BufferedImage;

/**
 * A filter which can be used to produce wipes by transferring the luma of a
 * mask image into the alpha channel of the source.
 */
public class GradientWipeFilter extends AbstractBufferedImageOp {

    private float density = 0;
    private float softness = 0;
    private boolean invert;
    private BufferedImage mask;

    public GradientWipeFilter() {
    }

    /**
     * Set the density of the image in the range 0..1.*arg density The density
     * @param density Density
     */
    public void setDensity(float density) {
        this.density = density;
    }

    public float getDensity() {
        return density;
    }

    /**
     * Set the softness of the dissolve in the range 0..1.
     *
     * @param softness the softness
     * min-value 0
     * max-value 1
     * @see #getSoftness
     */
    public void setSoftness(float softness) {
        this.softness = softness;
    }

    /**
     * Get the softness of the dissolve.
     *
     * @return the softness
     * @see #setSoftness
     */
    public float getSoftness() {
        return softness;
    }

    public void setMask(BufferedImage mask) {
        this.mask = mask;
    }

    public BufferedImage getMask() {
        return mask;
    }

    public void setInvert(boolean invert) {
        this.invert = invert;
    }

    public boolean getInvert() {
        return invert;
    }

    public BufferedImage filter(BufferedImage src, BufferedImage dst) {
        int width = src.getWidth();
        int height = src.getHeight();

        if (dst == null) {
            dst = createCompatibleDestImage(src, null);
        }
        if (mask == null) {
            return dst;
        }

        int maskWidth = mask.getWidth();
        int maskHeight = mask.getHeight();

        float d = density * (1 + softness);
        float lower = 255 * (d - softness);
        float upper = 255 * d;

        int[] inPixels = new int[width];
        int[] maskPixels = new int[maskWidth];

        for (int y = 0; y < height; y++) {
            getRGB(src, 0, y, width, 1, inPixels);
            getRGB(mask, 0, y % maskHeight, maskWidth, 1, maskPixels);

            for (int x = 0; x < width; x++) {
                int maskRGB = maskPixels[x % maskWidth];
                int inRGB = inPixels[x];
                int v = PixelUtils.brightness(maskRGB);
                float f = ImageMath.smoothStep(lower, upper, v);
                int a = (int) (255 * f);

                if (invert) {
                    a = 255 - a;
                }
                inPixels[x] = (a << 24) | (inRGB & 0x00ffffff);
            }

            setRGB(dst, 0, y, width, 1, inPixels);
        }

        return dst;
    }

    public String toString() {
        return "Transitions/Gradient Wipe...";
    }
}
