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bower_components/iron-range-behavior/iron-range-behavior.html 2.52 KB
73bcce88   luigser   COMPONENTS
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  <!--
  @license
  Copyright (c) 2015 The Polymer Project Authors. All rights reserved.
  This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
  The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
  The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
  Code distributed by Google as part of the polymer project is also
  subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
  -->
  
  <link rel="import" href="../polymer/polymer.html">
  
  <script>
  
   /** 
   * `iron-range-behavior` provides the behavior for something with a minimum to maximum range.
   *
   * @demo demo/index.html
   * @polymerBehavior 
   */
   Polymer.IronRangeBehavior = {
  
    properties: {
  
      /**
       * The number that represents the current value.
       */
      value: {
        type: Number,
        value: 0,
        notify: true,
        reflectToAttribute: true
      },
  
      /**
       * The number that indicates the minimum value of the range.
       */
      min: {
        type: Number,
        value: 0,
        notify: true
      },
  
      /**
       * The number that indicates the maximum value of the range.
       */
      max: {
        type: Number,
        value: 100,
        notify: true
      },
  
      /**
       * Specifies the value granularity of the range's value.
       */
      step: {
        type: Number,
        value: 1,
        notify: true
      },
  
      /**
       * Returns the ratio of the value.
       */
      ratio: {
        type: Number,
        value: 0,
        readOnly: true,
        notify: true
      },
    },
  
    observers: [
      '_update(value, min, max, step)'
    ],
  
    _calcRatio: function(value) {
      return (this._clampValue(value) - this.min) / (this.max - this.min);
    },
  
    _clampValue: function(value) {
      return Math.min(this.max, Math.max(this.min, this._calcStep(value)));
    },
  
    _calcStep: function(value) {
     /**
      * if we calculate the step using
      * `Math.round(value / step) * step` we may hit a precision point issue 
      * eg. 0.1 * 0.2 =  0.020000000000000004
      * http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html
      *
      * as a work around we can divide by the reciprocal of `step`
      */
      return this.step ? (Math.round(value / this.step) / (1 / this.step)) : value;
    },
  
    _validateValue: function() {
      var v = this._clampValue(this.value);
      this.value = this.oldValue = isNaN(v) ? this.oldValue : v;
      return this.value !== v;
    },
  
    _update: function() {
      this._validateValue();
      this._setRatio(this._calcRatio(this.value) * 100);
    }
  
  };
  </script>