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 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.setX(0);
			child.setY(0);
			if (child.getWidth() != width || child.getHeight() != height) {
				child.setWidth(width);
				child.setHeight(height);
				if (child instanceof Layout) {
					Layout layout = (Layout) child;
					layout.invalidate();
					layout.validate();
				}
			} else {
				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;
	}
}