basic-timer-selection/basic-timer-selection.html at master · basic-web-components/basic-timer-selection · GitHub

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<!--
An aspect which provides for automatic timed changes in selection, as in a
automated slideshow.

@element basic-timer-selection
-->

<link rel="import" href="../basic-aspect/basic-aspect.html">

<script>
window.Basic = window.Basic || {};

window.Basic.TimerSelection = {

  contribute: {

    contentChanged: function() {
      this.collective.play();
    },

    /**
     * Begin automatic progression of the selection.
     *
     * @method play
     */
    play: function() {
      this._playing = true;
      this._setTimeout();
    },

    /**
     * Pause automatic progression of the selection.
     *
     * @method pause
     */
    pause: function() {
      this._clearTimeout();
      this._playing = false;
    },

    /**
     * True if the selection is being automatically advanced.
     *
     * @property playing
     * @type Boolean
     */
    get playing() {
      return this._playing;
    },
    set playing(playing) {
      if (playing) {
        if (!this._playing) {
          this.collective.play();
        }
      } else {
        if (this._playing) {
          this.collective.pause();
        }
      }
    },

    // Default implementations. These will be typically be handled by other
    // aspects in the collective.
    selectFirst: Basic.Collective.defaultMethod,
    selectNext: Basic.Collective.defaultMethod,

    // Whether the user has selected an item manually, or we've automatically
    // advanced the selection, we wait for a bit before advancing again.
    set selectedItem(item) {
      this._clearTimeout();
      if (this.collective.playing) {
        this._setTimeout();
      }
    }

  },

  name: 'TimerSelection',

  _clearTimeout: function() {
    if (this._timeout) {
      clearTimeout(this._timeout);
      this._timeout = null;
    }
  },

  _playing: false,

  _setTimeout: function() {
    this._timeout = setTimeout(this._selectNextWithWrap.bind(this), 2000);
  },

  // Select the next item, wrapping to first item if necessary.
  _selectNextWithWrap: function() {
    var items = this.collective.items;
    if (items) {
      if (this.collective.selectedIndex == null || this.collective.selectedIndex === items.length - 1) {
        this.collective.selectFirst();
      } else {
        this.collective.selectNext();
      }
    }
  },

  _timeout: null

};


Polymer({

  aspects: [Basic.TimerSelection],

  behaviors: [Basic.Aspect],

  is: 'basic-timer-selection',

  play: function() {
    this.collective.play();
  },

  get playing() {
    return this.collective.playing;
  },
  set playing(playing) {
    this.collective.playing = playing;
  },

  pause: function() {
    this.collective.pause();
  }

});
</script>