Stack.java

/*******************************************************************************
 * Copyright (c) 2011, Nathan Sweet <nathan.sweet@gmail.com>
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the <organization> nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 ******************************************************************************/

package com.badlogic.gdx.scenes.scene2d.ui;

import com.badlogic.gdx.scenes.scene2d.Actor;
import com.badlogic.gdx.scenes.scene2d.Touchable;
import com.badlogic.gdx.scenes.scene2d.utils.Layout;
import com.badlogic.gdx.utils.Array;
import com.badlogic.gdx.utils.SnapshotArray;

/** A stack is a container that sizes its children to its size and positions them at 0,0 on top of each other.
 * <p>
 * The preferred and min size of the stack is the largest preferred and min size of any children. The max size of the stack is the
 * smallest max size of any children.
 * @author Nathan Sweet */
public class Stack extends WidgetGroup {
	private float prefWidth, prefHeight, minWidth, minHeight, maxWidth, maxHeight;
	private boolean sizeInvalid = true;

	public Stack () {
		setTransform(false);
		setWidth(150);
		setHeight(150);
		setTouchable(Touchable.childrenOnly);
	}

	public Stack (Actor... actors) {
		this();
		for (Actor actor : actors)
			addActor(actor);
	}

	public void invalidate () {
		super.invalidate();
		sizeInvalid = true;
	}

	private void computeSize () {
		sizeInvalid = false;
		prefWidth = 0;
		prefHeight = 0;
		minWidth = 0;
		minHeight = 0;
		maxWidth = 0;
		maxHeight = 0;
		SnapshotArray<Actor> children = getChildren();
		for (int i = 0, n = children.size; i < n; i++) {
			Actor child = children.get(i);
			float childMaxWidth, childMaxHeight;
			if (child instanceof Layout) {
				Layout layout = (Layout)child;
				prefWidth = Math.max(prefWidth, layout.getPrefWidth());
				prefHeight = Math.max(prefHeight, layout.getPrefHeight());
				minWidth = Math.max(minWidth, layout.getMinWidth());
				minHeight = Math.max(minHeight, layout.getMinHeight());
				childMaxWidth = layout.getMaxWidth();
				childMaxHeight = layout.getMaxHeight();
			} else {
				prefWidth = Math.max(prefWidth, child.getWidth());
				prefHeight = Math.max(prefHeight, child.getHeight());
				minWidth = Math.max(minWidth, child.getWidth());
				minHeight = Math.max(minHeight, child.getHeight());
				childMaxWidth = 0;
				childMaxHeight = 0;
			}
			if (childMaxWidth > 0) maxWidth = maxWidth == 0 ? childMaxWidth : Math.min(maxWidth, childMaxWidth);
			if (childMaxHeight > 0) maxHeight = maxHeight == 0 ? childMaxHeight : Math.min(maxHeight, childMaxHeight);
		}
	}

	public void add (Actor actor) {
		addActor(actor);
	}

	public void layout () {
		if (sizeInvalid) computeSize();
		float width = getWidth(), height = getHeight();
		Array<Actor> children = getChildren();
		for (int i = 0, n = children.size; i < n; i++) {
			Actor child = children.get(i);
			child.setBounds(0, 0, width, height);
			if (child instanceof Layout) ((Layout)child).validate();
		}
	}

	public float getPrefWidth () {
		if (sizeInvalid) computeSize();
		return prefWidth;
	}

	public float getPrefHeight () {
		if (sizeInvalid) computeSize();
		return prefHeight;
	}

	public float getMinWidth () {
		if (sizeInvalid) computeSize();
		return minWidth;
	}

	public float getMinHeight () {
		if (sizeInvalid) computeSize();
		return minHeight;
	}

	public float getMaxWidth () {
		if (sizeInvalid) computeSize();
		return maxWidth;
	}

	public float getMaxHeight () {
		if (sizeInvalid) computeSize();
		return maxHeight;
	}
}