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| 1 <!-- |
| 2 @license |
| 3 Copyright (c) 2015 The Polymer Project Authors. All rights reserved. |
| 4 This code may only be used under the BSD style license found at http://polymer.g
ithub.io/LICENSE.txt |
| 5 The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt |
| 6 The complete set of contributors may be found at http://polymer.github.io/CONTRI
BUTORS.txt |
| 7 Code distributed by Google as part of the polymer project is also |
| 8 subject to an additional IP rights grant found at http://polymer.github.io/PATEN
TS.txt |
| 9 --> |
| 10 |
| 11 <link rel="import" href="../polymer/polymer.html"> |
| 12 |
| 13 <!-- |
| 14 `iron-a11y-announcer` is a singleton element that is intended to add a11y |
| 15 to features that require on-demand announcement from screen readers. In |
| 16 order to make use of the announcer, it is best to request its availability |
| 17 in the announcing element. |
| 18 |
| 19 Example: |
| 20 |
| 21 Polymer({ |
| 22 |
| 23 is: 'x-chatty', |
| 24 |
| 25 attached: function() { |
| 26 // This will create the singlton element if it has not |
| 27 // been created yet: |
| 28 Polymer.IronA11yAnnouncer.requestAvailability(); |
| 29 } |
| 30 }); |
| 31 |
| 32 After the `iron-a11y-announcer` has been made available, elements can |
| 33 make announces by firing bubbling `iron-announce` events. |
| 34 |
| 35 Example: |
| 36 |
| 37 this.fire('iron-announce', { |
| 38 text: 'This is an announcement!' |
| 39 }, { bubbles: true }); |
| 40 |
| 41 Note: announcements are only audible if you have a screen reader enabled. |
| 42 |
| 43 @group Iron Elements |
| 44 @demo demo/index.html |
| 45 --> |
| 46 |
| 47 <dom-module id="iron-a11y-announcer"> |
| 48 <style> |
| 49 :host { |
| 50 display: inline-block; |
| 51 position: fixed; |
| 52 clip: rect(0px,0px,0px,0px); |
| 53 } |
| 54 </style> |
| 55 |
| 56 <template> |
| 57 <span aria-live$="[[mode]]">[[_text]]</span> |
| 58 </template> |
| 59 |
| 60 <script> |
| 61 |
| 62 (function() { |
| 63 'use strict'; |
| 64 |
| 65 Polymer.IronA11yAnnouncer = Polymer({ |
| 66 is: 'iron-a11y-announcer', |
| 67 |
| 68 properties: { |
| 69 |
| 70 /** |
| 71 * The value of mode is used to set the `aria-live` attribute |
| 72 * for the element that will be announced. Valid values are: `off`, |
| 73 * `polite` and `assertive`. |
| 74 */ |
| 75 mode: { |
| 76 type: String, |
| 77 value: 'polite' |
| 78 }, |
| 79 |
| 80 _text: { |
| 81 type: String, |
| 82 value: '' |
| 83 } |
| 84 }, |
| 85 |
| 86 created: function() { |
| 87 if (!Polymer.IronA11yAnnouncer.instance) { |
| 88 Polymer.IronA11yAnnouncer.instance = this; |
| 89 } |
| 90 |
| 91 document.body.addEventListener('iron-announce', this._onIronAnnounce.b
ind(this)); |
| 92 }, |
| 93 |
| 94 /** |
| 95 * Cause a text string to be announced by screen readers. |
| 96 * |
| 97 * @param {string} text The text that should be announced. |
| 98 */ |
| 99 announce: function(text) { |
| 100 this._text = ''; |
| 101 this.async(function() { |
| 102 this._text = text; |
| 103 }, 100); |
| 104 }, |
| 105 |
| 106 _onIronAnnounce: function(event) { |
| 107 if (event.detail && event.detail.text) { |
| 108 this.announce(event.detail.text); |
| 109 } |
| 110 } |
| 111 }); |
| 112 |
| 113 Polymer.IronA11yAnnouncer.instance = null; |
| 114 |
| 115 Polymer.IronA11yAnnouncer.requestAvailability = function() { |
| 116 if (!Polymer.IronA11yAnnouncer.instance) { |
| 117 document.createElement('iron-a11y-announcer'); |
| 118 } |
| 119 |
| 120 document.body.appendChild(Polymer.IronA11yAnnouncer.instance); |
| 121 }; |
| 122 })(); |
| 123 |
| 124 </script> |
| 125 </dom-module> |
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