/*
** Copyright 2005 Huxtable.com. All rights reserved.
*/

package com.jhlabs.image;

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

public class ShadowFilter extends AbstractBufferedImageOp {

	static final long serialVersionUID = 6310370419462785691L;
	
	private int radius = 5;
	private int xOffset = 5;
	private int yOffset = 5;
	private float opacity = 0.5f;
	private boolean addMargins = false;
	private boolean shadowOnly = false;
	private int shadowColor = 0xff000000;

	public ShadowFilter() {
	}

	public ShadowFilter(int radius, int xOffset, int yOffset, float opacity) {
		this.radius = radius;
		this.xOffset = xOffset;
		this.yOffset = yOffset;
		this.opacity = opacity;
	}

	public void setXOffset(int xOffset) {
		this.xOffset = xOffset;
	}

	public int getXOffset() {
		return xOffset;
	}

	public void setYOffset(int yOffset) {
		this.yOffset = yOffset;
	}

	public int getYOffset() {
		return yOffset;
	}

	/**
	 * Set the radius of the kernel, and hence the amount of blur. The bigger the radius, the longer this filter will take.
	 * @param radius the radius of the blur in pixels.
	 */
	public void setRadius(int radius) {
		this.radius = radius;
	}
	
	/**
	 * Get the radius of the kernel.
	 * @return the radius
	 */
	public int getRadius() {
		return radius;
	}

	public void setOpacity(float opacity) {
		this.opacity = opacity;
	}

	public float getOpacity() {
		return opacity;
	}

	public void setShadowColor(int shadowColor) {
		this.shadowColor = shadowColor;
	}

	public int getShadowColor() {
		return shadowColor;
	}

	public void setAddMargins(boolean addMargins) {
		this.addMargins = addMargins;
	}

	public boolean getAddMargins() {
		return addMargins;
	}

	public void setShadowOnly(boolean shadowOnly) {
		this.shadowOnly = shadowOnly;
	}

	public boolean getShadowOnly() {
		return shadowOnly;
	}

	protected void transformSpace(Rectangle r) {
		if ( addMargins ) {
			r.width += Math.abs(xOffset)+2*radius;
			r.height += Math.abs(yOffset)+2*radius;
		}
	}

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

        if ( dst == null ) {
            if ( addMargins ) {
				ColorModel cm = src.getColorModel();
				dst = new BufferedImage(cm, cm.createCompatibleWritableRaster(src.getWidth(), src.getHeight()), cm.isAlphaPremultiplied(), null);
			} else
				dst = createCompatibleDestImage( src, null );
		}

        // Make a black mask from the image's alpha channel 
        float[][] extractAlpha = {
            { 0, 0, 0, 0 },
            { 0, 0, 0, 0 },
            { 0, 0, 0, 0 },
            { 0, 0, 0, opacity }
        };
        BufferedImage shadow = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
        new BandCombineOp( extractAlpha, null ).filter( src.getRaster(), shadow.getRaster() );
        shadow = new GaussianFilter( radius ).filter( shadow, null );

		Graphics2D g = dst.createGraphics();
		g.setComposite( AlphaComposite.getInstance( AlphaComposite.SRC_OVER, opacity ) );
		if ( addMargins ) {
			int radius2 = radius/2;
			int topShadow = Math.max( 0, radius-yOffset );
			int leftShadow = Math.max( 0, radius-xOffset );
			g.translate( topShadow, leftShadow );
		}
		g.drawRenderedImage( shadow, AffineTransform.getTranslateInstance( xOffset, yOffset ) );
		if ( !shadowOnly ) {
			g.setComposite( AlphaComposite.SrcOver );
			g.drawRenderedImage( src, null );
		}
		g.dispose();

        return dst;
	}

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