/******************************************************************************
 * Copyright (c) 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    IBM Corporation - initial API and implementation 
 ****************************************************************************/

package org.eclipse.gmf.runtime.draw2d.ui.figures;

import org.eclipse.draw2d.ColorConstants;
import org.eclipse.draw2d.Graphics;
import org.eclipse.draw2d.IFigure;
import org.eclipse.draw2d.geometry.Dimension;
import org.eclipse.draw2d.geometry.Point;
import org.eclipse.draw2d.geometry.Rectangle;
import org.eclipse.gmf.runtime.draw2d.ui.internal.l10n.Draw2dUIPluginImages;
import org.eclipse.gmf.runtime.draw2d.ui.mapmode.MapModeUtil;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.ImageData;
import org.eclipse.swt.widgets.Display;

/**
 * @author choang
 *
 * Drop Shadow Helper Class to help draw shadow on borders
 */
public class RectangularDropShadow {

	/**
	 * 
	 */
	public RectangularDropShadow() {
		super();
		// TODO Auto-generated constructor stub
	}
	
	//	Images for the border of the shadow border
	private static ImageData alpha_ilb = 
		Draw2dUIPluginImages.DESC_LEFT_BOTTOM.getImageData();

	private static ImageData alpha_irb = 
		Draw2dUIPluginImages.DESC_RIGHT_BOTTOM.getImageData();

	private static ImageData alpha_ir = 
		Draw2dUIPluginImages.DESC_RIGHT.getImageData();

	private static ImageData alpha_itr = 
		Draw2dUIPluginImages.DESC_TOP_RIGHT.getImageData();

	private static ImageData alpha_ib = 
		Draw2dUIPluginImages.DESC_BOTTOM.getImageData();
		 
	/**
	 * Method for determining the width of the drop shadow border will take up on the shape.
	 * @return int the width of the drop shadow
	 */
	public int getShadowWidth() {
		return alpha_ir.width;
	}

	/**
	 * Method for determining the height of the drop shadow border will take up on the shape.
	 * @return int the height of the drop shadow
	 */
	public int getShadowHeight() {
		return alpha_ib.height;
	}
	
	/**
	 * draw a shadow around given rectangle @rect
	 * @param figure
	 * @param g
	 * @param rect the rectangle to draw the shadow around
	 */
	public void drawShadow(IFigure figure, Graphics g, Rectangle rect){
		
		drawBottomLeftShadow(figure, g, rect);

		// bottom
		drawBottomShadow(figure, g, rect);

		// bottom right
		drawBottomRightShadow(figure, g, rect);

		// right
		drawRightShadow(figure, g, rect);

		// top right
		drawTopRightShadow(figure, g, rect);

	}
	
	/**
	 * @param figure
	 * @param g
	 * @param rBox
	 */
	protected void drawTopRightShadow(IFigure figure, Graphics g, Rectangle rBox) {
		Dimension dim = new Dimension(alpha_itr.width, alpha_itr.height);
		Image itr = createImageFromAlpha(figure, alpha_itr, dim);
		Point pt = new Point(rBox.getRight().x - MapModeUtil.getMapMode(figure).DPtoLP(alpha_ir.width),
			rBox.getTop().y );
		g.drawImage(itr, pt);
		itr.dispose();
	}

	/**
	 * @param figure
	 * @param g
	 * @param rBox
	 */
	protected void drawRightShadow(IFigure figure, Graphics g, Rectangle rBox) {
		Dimension dim = getRightShadowDimension(figure, rBox);
		Image ir = createImageFromAlpha(figure, alpha_ir, dim);
		Point pt = 
			new Point(
				rBox.getRight().x - MapModeUtil.getMapMode(figure).DPtoLP(alpha_ir.width),
				rBox.getTop().y + MapModeUtil.getMapMode(figure).DPtoLP(alpha_itr.height)) ;
		g.drawImage(ir, pt);
		ir.dispose();
	}

	/**
	 * @param figure
	 * @param g
	 * @param rBox
	 */
	protected void drawBottomRightShadow(
		IFigure figure,
		Graphics g,
		Rectangle rBox) {
		Dimension dim;
		dim = getBottomRightShadowDimension();
		Image irb = createImageFromAlpha(figure, alpha_irb, dim);
		
		Point pt =
			new Point(
				rBox.getRight().x - MapModeUtil.getMapMode(figure).DPtoLP(alpha_ir.width),
				rBox.getBottom().y - MapModeUtil.getMapMode(figure).DPtoLP(alpha_ib.height) );
		g.drawImage(irb, pt);
		irb.dispose();
	}

	/**
	 * @param figure
	 * @param g
	 * @param rBox
	 */
	protected void drawBottomShadow(IFigure figure, Graphics g, Rectangle rBox) {
		
		Dimension dim = getBottomShadowDimension(figure, rBox);
		Image ib = createImageFromAlpha(figure, alpha_ib, dim);
		Point pt =
			new Point(
				rBox.getLeft().x + MapModeUtil.getMapMode(figure).DPtoLP(alpha_ilb.width),
				rBox.getBottom().y - MapModeUtil.getMapMode(figure).DPtoLP(alpha_ib.height) );
		g.drawImage(ib, pt);
		ib.dispose();
	}

	/**
	 * @param figure
	 * @param g
	 * @param rBox
	 */
	private void drawBottomLeftShadow(IFigure figure, Graphics g, Rectangle rBox) {
		Dimension dim = getLeftShadowDimension();
		Image ilb = createImageFromAlpha(figure, alpha_ilb, dim);
		Point pt =
			new Point(rBox.getLeft().x,
				rBox.getBottom().y - MapModeUtil.getMapMode(figure).DPtoLP(alpha_ib.height) );
		g.drawImage(ilb, pt);
		ilb.dispose();
	}

	/**
	 * @param figure
	 * @param rBox
	 * @return the <code>Dimension</code> representing the right shadow
	 */
	protected Dimension getRightShadowDimension(IFigure figure, Rectangle rBox) {

		int height = Math.max(MapModeUtil.getMapMode(figure).LPtoDP(rBox.height) - alpha_itr.height - alpha_irb.height,
			1);
		return new Dimension(alpha_ir.width, height);
	}

	/**
	 * @return the <code>Dimension</code> representing the bottom right shadow
	 */
	protected Dimension getBottomRightShadowDimension() {
		return new Dimension(alpha_irb.width, alpha_irb.height);
	}

	/**
	 * @param rBox
	 * @return the <code>Dimension</code> representing the bottom shadow
	 */
	protected Dimension getBottomShadowDimension(IFigure figure, Rectangle rBox) {

		int width = Math.max(MapModeUtil.getMapMode(figure).LPtoDP( rBox.width ) - alpha_ilb.width - alpha_irb.width,
			1);
		return new Dimension(width, alpha_ib.height);
	}

	/**
	 * @return the <code>Dimension</code> representing the left shadow
	 */
	protected Dimension getLeftShadowDimension() {
		return new Dimension(alpha_ilb.width, alpha_ilb.height);
	}
	
	/**
	 * Utility function for the paint routine to create the image that will be displayed
	 * based on a transparency image. 
	 */
	private Image createImageFromAlpha(
		IFigure figure,
		ImageData alphaData,
		Dimension dim) {
		Color foreColor = figure.getForegroundColor();

		ImageData newAlpha = alphaData;
		if (alphaData.width != dim.width || alphaData.height != dim.height) {
			ImageData newAlphaData =
				new ImageData(
					((dim.width + 3) / 4) * 4,
					dim.height,
					alphaData.depth,
					alphaData.palette);
			Image imgNewAlpha = new Image(null, newAlphaData);
			GC gc = new GC(imgNewAlpha);

			Image imgAlpha = new Image(null, alphaData);
			gc.drawImage(
				imgAlpha,
				0,
				0,
				alphaData.width,
				alphaData.height,
				0,
				0,
				newAlphaData.width,
				newAlphaData.height);

			int nDelta = newAlphaData.width - dim.width;
			if (nDelta > 0) {
				gc.setForeground(ColorConstants.black);
				gc.setBackground(ColorConstants.black);
				gc.fillRectangle(
					newAlphaData.width - nDelta,
					0,
					nDelta,
					newAlphaData.height);
			}

			newAlpha = imgNewAlpha.getImageData();

			imgNewAlpha.dispose();
			imgAlpha.dispose();
			gc.dispose();
		}

		Image img =
			new Image(Display.getDefault(), newAlpha.width, newAlpha.height);

		GC gc = new GC(img);
		gc.setForeground(foreColor);
		gc.setBackground(foreColor);
		gc.fillRectangle(0, 0, newAlpha.width, newAlpha.height);
		gc.dispose();

		ImageData filledData = img.getImageData();
		img.dispose();

		for (int i = 0; i < newAlpha.height; i++) {
			filledData.setAlphas(
				0,
				i,
				newAlpha.width,
				newAlpha.data,
				i * newAlpha.width);
		}

		return new Image(null, filledData);
	}

}