text: // Copyright 2011 The Closure Library Authors. All Rights Reserved.
  //
  // 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.
  
  /**
   * @fileoverview An abstract base class for transitions. This is a simple
   * interface that allows for playing, pausing and stopping an animation. It adds
   * a simple event model, and animation status.
   */
  goog.provide('goog.fx.TransitionBase');
  goog.provide('goog.fx.TransitionBase.State');
  
  goog.require('goog.events.EventTarget');
  goog.require('goog.fx.Transition');  // Unreferenced: interface
  goog.require('goog.fx.Transition.EventType');
  
  
  
  /**
   * Constructor for a transition object.
   *
   * @constructor
   * @implements {goog.fx.Transition}
   * @extends {goog.events.EventTarget}
   */
  goog.fx.TransitionBase = function() {
    goog.base(this);
  
    /**
     * The internal state of the animation.
     * @type {goog.fx.TransitionBase.State}
     * @private
     */
    this.state_ = goog.fx.TransitionBase.State.STOPPED;
  
    /**
     * Timestamp for when the animation was started.
     * @type {?number}
     * @protected
     */
    this.startTime = null;
  
    /**
     * Timestamp for when the animation finished or was stopped.
     * @type {?number}
     * @protected
     */
    this.endTime = null;
  };
  goog.inherits(goog.fx.TransitionBase, goog.events.EventTarget);
  
  
  /**
   * Enum for the possible states of an animation.
   * @enum {number}
   */
  goog.fx.TransitionBase.State = {
    STOPPED: 0,
    PAUSED: -1,
    PLAYING: 1
  };
  
  
  /**
   * Plays the animation.
   *
   * @param {boolean=} opt_restart Optional parameter to restart the animation.
   * @return {boolean} True iff the animation was started.
   * @override
   */
  goog.fx.TransitionBase.prototype.play = goog.abstractMethod;
  
  
  /**
   * Stops the animation.
   *
   * @param {boolean=} opt_gotoEnd Optional boolean parameter to go the the end of
   *     the animation.
   * @override
   */
  goog.fx.TransitionBase.prototype.stop = goog.abstractMethod;
  
  
  /**
   * Pauses the animation.
   */
  goog.fx.TransitionBase.prototype.pause = goog.abstractMethod;
  
  
  /**
   * Returns the current state of the animation.
   * @return {goog.fx.TransitionBase.State} State of the animation.
   */
  goog.fx.TransitionBase.prototype.getStateInternal = function() {
    return this.state_;
  };
  
  
  /**
   * Sets the current state of the animation to playing.
   * @protected
   */
  goog.fx.TransitionBase.prototype.setStatePlaying = function() {
    this.state_ = goog.fx.TransitionBase.State.PLAYING;
  };
  
  
  /**
   * Sets the current state of the animation to paused.
   * @protected
   */
  goog.fx.TransitionBase.prototype.setStatePaused = function() {
    this.state_ = goog.fx.TransitionBase.State.PAUSED;
  };
  
  
  /**
   * Sets the current state of the animation to stopped.
   * @protected
   */
  goog.fx.TransitionBase.prototype.setStateStopped = function() {
    this.state_ = goog.fx.TransitionBase.State.STOPPED;
  };
  
  
  /**
   * @return {boolean} True iff the current state of the animation is playing.
   */
  goog.fx.TransitionBase.prototype.isPlaying = function() {
    return this.state_ == goog.fx.TransitionBase.State.PLAYING;
  };
  
  
  /**
   * @return {boolean} True iff the current state of the animation is paused.
   */
  goog.fx.TransitionBase.prototype.isPaused = function() {
    return this.state_ == goog.fx.TransitionBase.State.PAUSED;
  };
  
  
  /**
   * @return {boolean} True iff the current state of the animation is stopped.
   */
  goog.fx.TransitionBase.prototype.isStopped = function() {
    return this.state_ == goog.fx.TransitionBase.State.STOPPED;
  };
  
  
  /**
   * Dispatches the BEGIN event. Sub classes should override this instead
   * of listening to the event, and call this instead of dispatching the event.
   * @protected
   */
  goog.fx.TransitionBase.prototype.onBegin = function() {
    this.dispatchAnimationEvent(goog.fx.Transition.EventType.BEGIN);
  };
  
  
  /**
   * Dispatches the END event. Sub classes should override this instead
   * of listening to the event, and call this instead of dispatching the event.
   * @protected
   */
  goog.fx.TransitionBase.prototype.onEnd = function() {
    this.dispatchAnimationEvent(goog.fx.Transition.EventType.END);
  };
  
  
  /**
   * Dispatches the FINISH event. Sub classes should override this instead
   * of listening to the event, and call this instead of dispatching the event.
   * @protected
   */
  goog.fx.TransitionBase.prototype.onFinish = function() {
    this.dispatchAnimationEvent(goog.fx.Transition.EventType.FINISH);
  };
  
  
  /**
   * Dispatches the PAUSE event. Sub classes should override this instead
   * of listening to the event, and call this instead of dispatching the event.
   * @protected
   */
  goog.fx.TransitionBase.prototype.onPause = function() {
    this.dispatchAnimationEvent(goog.fx.Transition.EventType.PAUSE);
  };
  
  
  /**
   * Dispatches the PLAY event. Sub classes should override this instead
   * of listening to the event, and call this instead of dispatching the event.
   * @protected
   */
  goog.fx.TransitionBase.prototype.onPlay = function() {
    this.dispatchAnimationEvent(goog.fx.Transition.EventType.PLAY);
  };
  
  
  /**
   * Dispatches the RESUME event. Sub classes should override this instead
   * of listening to the event, and call this instead of dispatching the event.
   * @protected
   */
  goog.fx.TransitionBase.prototype.onResume = function() {
    this.dispatchAnimationEvent(goog.fx.Transition.EventType.RESUME);
  };
  
  
  /**
   * Dispatches the STOP event. Sub classes should override this instead
   * of listening to the event, and call this instead of dispatching the event.
   * @protected
   */
  goog.fx.TransitionBase.prototype.onStop = function() {
    this.dispatchAnimationEvent(goog.fx.Transition.EventType.STOP);
  };
  
  
  /**
   * Dispatches an event object for the current animation.
   * @param {string} type Event type that will be dispatched.
   * @protected
   */
  goog.fx.TransitionBase.prototype.dispatchAnimationEvent = function(type) {
    this.dispatchEvent(type);
  };
  