123 lines
3.1 KiB
HTML
123 lines
3.1 KiB
HTML
<!--
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@license
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Copyright (c) 2015 The Polymer Project Authors. All rights reserved.
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This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
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The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
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The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
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Code distributed by Google as part of the polymer project is also
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subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
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-->
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<link rel="import" href="../polymer/polymer.html">
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<!--
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`iron-a11y-announcer` is a singleton element that is intended to add a11y
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to features that require on-demand announcement from screen readers. In
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order to make use of the announcer, it is best to request its availability
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in the announcing element.
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Example:
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Polymer({
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is: 'x-chatty',
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attached: function() {
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// This will create the singleton element if it has not
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// been created yet:
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Polymer.IronA11yAnnouncer.requestAvailability();
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}
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});
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After the `iron-a11y-announcer` has been made available, elements can
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make announces by firing bubbling `iron-announce` events.
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Example:
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this.fire('iron-announce', {
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text: 'This is an announcement!'
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}, { bubbles: true });
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Note: announcements are only audible if you have a screen reader enabled.
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@group Iron Elements
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@demo demo/index.html
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-->
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<dom-module id="iron-a11y-announcer">
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<template>
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<style>
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:host {
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display: inline-block;
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position: fixed;
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clip: rect(0px,0px,0px,0px);
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}
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</style>
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<div aria-live$="[[mode]]">[[_text]]</div>
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</template>
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</dom-module>
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<script>
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'use strict';
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(function() {
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'use strict';
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Polymer.IronA11yAnnouncer = Polymer({
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is: 'iron-a11y-announcer',
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properties: {
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/**
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* The value of mode is used to set the `aria-live` attribute
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* for the element that will be announced. Valid values are: `off`,
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* `polite` and `assertive`.
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*/
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mode: {
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type: String,
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value: 'polite'
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},
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_text: {
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type: String,
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value: ''
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}
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},
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created: function() {
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if (!Polymer.IronA11yAnnouncer.instance) {
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Polymer.IronA11yAnnouncer.instance = this;
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}
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document.body.addEventListener('iron-announce', this._onIronAnnounce.bind(this));
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},
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/**
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* Cause a text string to be announced by screen readers.
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*
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* @param {string} text The text that should be announced.
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*/
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announce: function(text) {
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this._text = '';
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this.async(function() {
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this._text = text;
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}, 100);
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},
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_onIronAnnounce: function(event) {
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if (event.detail && event.detail.text) {
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this.announce(event.detail.text);
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}
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}
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});
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Polymer.IronA11yAnnouncer.instance = null;
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Polymer.IronA11yAnnouncer.requestAvailability = function() {
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if (!Polymer.IronA11yAnnouncer.instance) {
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Polymer.IronA11yAnnouncer.instance = document.createElement('iron-a11y-announcer');
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}
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document.body.appendChild(Polymer.IronA11yAnnouncer.instance);
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};
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})();
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</script>
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