ImageButton.java

/*******************************************************************************
 * Copyright 2011 See AUTHORS file.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations under the License.
 ******************************************************************************/

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

import com.badlogic.gdx.graphics.g2d.SpriteBatch;
import com.badlogic.gdx.scenes.scene2d.utils.Drawable;
import com.badlogic.gdx.utils.Scaling;
import com.esotericsoftware.tablelayout.Cell;

/**
 * A button with a child {@link Image} to display an image. This is useful when the button must be larger than the image
 * and the image centered on the button. If the image is the size of the button, a {@link Button} without any children
 * can be used, where the {@link Button.ButtonStyle#up}, {@link Button.ButtonStyle#down}, and
 * {@link Button.ButtonStyle#checked} nine patches define the image.
 * 
 * @author Nathan Sweet
 */
public class ImageButton extends Button {
	private final Image image;
	private ImageButtonStyle style;

	public ImageButton(Skin skin) {
		this(skin.get(ImageButtonStyle.class));
	}

	public ImageButton(Skin skin, String styleName) {
		this(skin.get(styleName, ImageButtonStyle.class));
	}

	public ImageButton(ImageButtonStyle style) {
		super(style);
		image = new Image();
		image.setScaling(Scaling.fit);
		add(image);
		setStyle(style);
		setWidth(getPrefWidth());
		setHeight(getPrefHeight());
	}

	public ImageButton(Drawable imageUp) {
		this(new ImageButtonStyle(null, null, null, imageUp, null, null));
	}

	public ImageButton(Drawable imageUp, Drawable imageDown) {
		this(new ImageButtonStyle(null, null, null, imageUp, imageDown, null));
	}

	public ImageButton(Drawable imageUp, Drawable imageDown, Drawable imageChecked) {
		this(new ImageButtonStyle(null, null, null, imageUp, imageDown, imageChecked));
	}

	public void setStyle(ButtonStyle style) {
		if (!(style instanceof ImageButtonStyle))
			throw new IllegalArgumentException("style must be an ImageButtonStyle.");
		super.setStyle(style);
		this.style = (ImageButtonStyle) style;
		if (image != null)
			updateImage();
	}

	public ImageButtonStyle getStyle() {
		return style;
	}

	private void updateImage() {
		boolean isPressed = isPressed();
		if (isDisabled && style.imageDisabled != null)
			image.setDrawable(style.imageDisabled);
		else if (isPressed && style.imageDown != null)
			image.setDrawable(style.imageDown);
		else if (isChecked && style.imageChecked != null)
			image.setDrawable((style.imageCheckedOver != null && isOver()) ? style.imageCheckedOver
					: style.imageChecked);
		else if (isOver() && style.imageOver != null)
			image.setDrawable(style.imageOver);
		else if (style.imageUp != null) //
			image.setDrawable(style.imageUp);
	}

	public void draw(SpriteBatch batch, float parentAlpha) {
		updateImage();
		super.draw(batch, parentAlpha);
	}

	public Image getImage() {
		return image;
	}

	public Cell getImageCell() {
		return getCell(image);
	}

	/**
	 * The style for an image button, see {@link ImageButton}.
	 * 
	 * @author Nathan Sweet
	 */
	static public class ImageButtonStyle extends ButtonStyle {
		/** Optional. */
		public Drawable imageUp, imageDown, imageOver, imageChecked, imageCheckedOver, imageDisabled;

		public ImageButtonStyle() {
		}

		public ImageButtonStyle(Drawable up, Drawable down, Drawable checked, Drawable imageUp, Drawable imageDown,
				Drawable imageChecked) {
			super(up, down, checked);
			this.imageUp = imageUp;
			this.imageDown = imageDown;
			this.imageChecked = imageChecked;
		}

		public ImageButtonStyle(ImageButtonStyle style) {
			super(style);
			this.imageUp = style.imageUp;
			this.imageDown = style.imageDown;
			this.imageOver = style.imageOver;
			this.imageChecked = style.imageChecked;
			this.imageCheckedOver = style.imageCheckedOver;
			this.imageDisabled = style.imageDisabled;
		}

		public ImageButtonStyle(ButtonStyle style) {
			super(style);
		}
	}
}