TemporalAction.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.actions;

import com.badlogic.gdx.math.Interpolation;
import com.badlogic.gdx.scenes.scene2d.Action;

/**
 * Base class for actions that transition over time using the percent complete.
 * 
 * @author Nathan Sweet
 */
abstract public class TemporalAction extends Action {
	private float duration, time;
	private Interpolation interpolation;
	private boolean reverse, complete;

	public TemporalAction() {
	}

	public TemporalAction(float duration) {
		this.duration = duration;
	}

	public TemporalAction(float duration, Interpolation interpolation) {
		this.duration = duration;
		this.interpolation = interpolation;
	}

	public boolean act(float delta) {
		if (complete)
			return true;
		if (time == 0)
			begin();
		time += delta;
		complete = time >= duration;
		float percent;
		if (complete)
			percent = 1;
		else {
			percent = time / duration;
			if (interpolation != null)
				percent = interpolation.apply(percent);
		}
		update(reverse ? 1 - percent : percent);
		if (complete)
			end();
		return complete;
	}

	/**
	 * Called the first time {@link #act(float)} is called. This is a good place to query the {@link #actor actor's}
	 * starting state.
	 */
	protected void begin() {
	}

	/** Called the last time {@link #act(float)} is called. */
	protected void end() {
	}

	/**
	 * Called each frame.
	 * 
	 * @param percent
	 *            The percentage of completion for this action, growing from 0 to 1 over the duration. If
	 *            {@link #setReverse(boolean) reversed}, this will shrink from 1 to 0.
	 */
	abstract protected void update(float percent);

	/** Skips to the end of the transition. */
	public void finish() {
		time = duration;
	}

	public void restart() {
		time = 0;
		complete = false;
	}

	public void reset() {
		super.reset();
		reverse = false;
		interpolation = null;
	}

	/** Gets the transition time so far. */
	public float getTime() {
		return time;
	}

	/** Sets the transition time so far. */
	public void setTime(float time) {
		this.time = time;
	}

	public float getDuration() {
		return duration;
	}

	/** Sets the length of the transition in seconds. */
	public void setDuration(float duration) {
		this.duration = duration;
	}

	public Interpolation getInterpolation() {
		return interpolation;
	}

	public void setInterpolation(Interpolation interpolation) {
		this.interpolation = interpolation;
	}

	public boolean isReverse() {
		return reverse;
	}

	/** When true, the action's progress will go from 100% to 0%. */
	public void setReverse(boolean reverse) {
		this.reverse = reverse;
	}
}