@qooxdoo/framework/source/class/qx/event/Idle.js

The JS Framework for Coders

/* ************************************************************************

   qooxdoo - the new era of web development

   http://qooxdoo.org

   Copyright:
     2004-2008 1&1 Internet AG, Germany, http://www.1und1.de

   License:
     MIT: https://opensource.org/licenses/MIT
     See the LICENSE file in the project's top-level directory for details.

   Authors:
     * Jonathan Weiß (jonathan_rass)

************************************************************************ */


/**
 * A generic singleton that fires an "interval" event all 100 milliseconds. It
 * can be used whenever one needs to run code periodically. The main purpose of
 * this class is reduce the number of timers.
 * 
 * NOTE: Instances of this class must be disposed of after use
 *
 */

qx.Class.define("qx.event.Idle",
{
  extend : qx.core.Object,
  implement : [ qx.core.IDisposable ],
  type : "singleton",

  construct : function()
  {
    this.base(arguments);
  },


  /*
  *****************************************************************************
     EVENTS
  *****************************************************************************
  */

  events :
  {
    /** This event if fired each time the interval time has elapsed */
    "interval" : "qx.event.type.Event"
  },


  /*
  *****************************************************************************
     PROPERTIES
  *****************************************************************************
  */

  properties :
  {
    /**
     * Interval for the timer, which periodically fires the "interval" event,
     * in milliseconds.
     */
    timeoutInterval :
    {
      check: "Number",
      init : 100,
      apply : "_applyTimeoutInterval"
    }
  },



  members :
  {

    __timer : null,

    // property apply
    _applyTimeoutInterval : function(value) {
      if (this.__timer) {
        this.__timer.setInterval(value);
      }
    },

    /**
     * Fires an "interval" event
     */
    _onInterval : function() {
      this.fireEvent("interval");
    },

    /**
     * Starts the timer but only if there are listeners for the "interval" event
     */
    __startTimer: function() {
      if (!this.__timer && this.hasListener("interval")) {
          var timer = new qx.event.Timer(this.getTimeoutInterval());
          timer.addListener("interval", this._onInterval, this);
          timer.start();

          this.__timer = timer;
      }
    },

    /**
     * Stops the timer but only if there are no listeners for the interval event
     */
    __stopTimer: function() {
      if (this.__timer && !this.hasListener("interval")) {
        this.__timer.stop();
        this.__timer.dispose();
        this.__timer = null;
      }
    },

    /*
     * @Override
     */
    addListener: function(type, listener, self, capture) {
      var result = this.base(arguments, type, listener, self, capture);
      this.__startTimer();
      return result;
    },

    /*
     * @Override
     */
    addListenerOnce: function(type, listener, self, capture) {
      var result = this.base(arguments, type, listener, self, capture);
      this.__startTimer();
      return result;
    },

    /*
     * @Override
     */
    removeListener: function(type, listener, self, capture) {
      var result = this.base(arguments, type, listener, self, capture);
      this.__stopTimer();
      return result;
    },

    /*
     * @Override
     */
    removeListenerById: function(id) {
      var result = this.base(arguments, id);
      this.__stopTimer();
      return result;
    }

  },

  /*
  *****************************************************************************
     DESTRUCTOR
  *****************************************************************************
  */

  destruct : function()
  {
    if (this.__timer) {
      this.__timer.stop();
    }

    this.__timer = null;
  }

});