Game.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;

/**
 * <p>
 * An {@link ApplicationListener} that delegates to a {@link Screen}. This allows an application to easily have multiple
 * screens.
 * </p>
 * <p>
 * Screens are not disposed automatically. You must handle whether you want to keep screens around or dispose of them
 * when another screen is set.
 * </p>
 */
public abstract class Game implements ApplicationListener {
	private Screen screen;

	@Override
	public void dispose() {
		if (screen != null)
			screen.hide();
	}

	@Override
	public void pause() {
		if (screen != null)
			screen.pause();
	}

	@Override
	public void resume() {
		if (screen != null)
			screen.resume();
	}

	@Override
	public void render() {
		if (screen != null)
			screen.render(Gdx.graphics.getDeltaTime());
	}

	@Override
	public void resize(int width, int height) {
		if (screen != null)
			screen.resize(width, height);
	}

	/**
	 * Sets the current screen. {@link Screen#hide()} is called on any old screen, and {@link Screen#show()} is called
	 * on the new screen, if any.
	 * 
	 * @param screen
	 *            may be {@code null}
	 */
	public void setScreen(Screen screen) {
		if (this.screen != null)
			this.screen.hide();
		this.screen = screen;
		if (this.screen != null) {
			this.screen.show();
			this.screen.resize(Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
		}
	}

	/** @return the currently active {@link Screen}. */
	public Screen getScreen() {
		return screen;
	}
}