/*******************************************************************************
 * Copyright (c) 2005, 2010 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.draw2d;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.eclipse.draw2d.geometry.Rectangle;

/**
 * Animates the layout of a figure's children. The animator will capture the
 * effects of a layout manager, and then play back the placement of children
 * using linear interpolation for each child's start and end locations.
 * <P>
 * To use an animator, hook it as a layout listener for the figure whose layout
 * is to be animated, by calling
 * {@link IFigure#addLayoutListener(LayoutListener)}. It is not necessary to
 * have an animator for every figure in a composition that is undergoing
 * animation. For example, if a figure without an animator moves during the
 * animation, it will continue to move and layout its children normally during
 * each step of the animation.
 * <P>
 * Animator must be used in conjunction with layouts. If figures are placed
 * manually using <code>setBounds()</code>, the animator may not be able to
 * track and playback the changes that occur.
 * 
 * @since 3.2
 */
public class LayoutAnimator extends Animator implements LayoutListener {

	static final LayoutAnimator INSTANCE = new LayoutAnimator();

	/**
	 * Constructs a new Animator. The default instance ({@link #getDefault()})
	 * can be used on all figures being animated.
	 * 
	 * @since 3.2
	 */
	protected LayoutAnimator() {
	}

	/**
	 * Returns an object encapsulating the placement of children in a container.
	 * This method is called to capture both the initial and final states.
	 * 
	 * @param container
	 *            the container figure
	 * @return the current state
	 * @since 3.2
	 */
	protected Object getCurrentState(IFigure container) {
		Map locations = new HashMap();
		List children = container.getChildren();
		IFigure child;
		for (int i = 0; i < children.size(); i++) {
			child = (IFigure) children.get(i);
			locations.put(child, child.getBounds().getCopy());
		}
		return locations;
	}

	/**
	 * Returns the default instance.
	 * 
	 * @return the default instance
	 * @since 3.2
	 */
	public static LayoutAnimator getDefault() {
		return INSTANCE;
	}

	/**
	 * Hooks invalidation in case animation is in progress.
	 * 
	 * @see LayoutListener#invalidate(IFigure)
	 */
	public final void invalidate(IFigure container) {
		if (Animation.isInitialRecording())
			Animation.hookAnimator(container, this);
	}

	/**
	 * Hooks layout in case animation is in progress.
	 * 
	 * @see org.eclipse.draw2d.LayoutListener#layout(org.eclipse.draw2d.IFigure)
	 */
	public final boolean layout(IFigure container) {
		if (Animation.isAnimating())
			return Animation.hookPlayback(container, this);
		return false;
	}

	/**
	 * Plays back the animated layout.
	 * 
	 * @see Animator#playback(IFigure)
	 */
	protected boolean playback(IFigure container) {
		Map initial = (Map) Animation.getInitialState(this, container);
		Map ending = (Map) Animation.getFinalState(this, container);
		if (initial == null)
			return false;
		List children = container.getChildren();

		float progress = Animation.getProgress();
		float ssergorp = 1 - progress;

		Rectangle rect1, rect2;

		for (int i = 0; i < children.size(); i++) {
			IFigure child = (IFigure) children.get(i);
			rect1 = (Rectangle) initial.get(child);
			rect2 = (Rectangle) ending.get(child);

			// TODO need to change this to hide the figure until the end.
			if (rect1 == null)
				continue;
			child.setBounds(new Rectangle(Math.round(progress * rect2.x
					+ ssergorp * rect1.x), Math.round(progress * rect2.y
					+ ssergorp * rect1.y), Math.round(progress * rect2.width
					+ ssergorp * rect1.width), Math.round(progress
					* rect2.height + ssergorp * rect1.height)));
		}
		return true;
	}

	/**
	 * Hooks post layout in case animation is in progress.
	 * 
	 * @see LayoutListener#postLayout(IFigure)
	 */
	public final void postLayout(IFigure container) {
		if (Animation.isFinalRecording())
			Animation.hookNeedsCapture(container, this);
	}

	/**
	 * This callback is unused. Reserved for possible future use.
	 * 
	 * @see LayoutListener#remove(IFigure)
	 */
	public final void remove(IFigure child) {
	}

	/**
	 * This callback is unused. Reserved for possible future use.
	 * 
	 * @see LayoutListener#setConstraint(IFigure, Object)
	 */
	public final void setConstraint(IFigure child, Object constraint) {
	}

}