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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) {
// polymer/issues/2493
value = parseFloat(value);
if (!this.step) {
return value;
}
var numSteps = Math.round((value - this.min) / this.step);
if (this.step < 1) {
/**
* For small values of this.step, 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 numSteps / (1 / this.step) + this.min;
} else {
return numSteps * this.step + this.min;
}
},
_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>
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