143 lines
4.1 KiB
JavaScript
143 lines
4.1 KiB
JavaScript
/**
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* Copyright (c) 2015-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*
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* @providesModule AccessibilityInfo
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* @flow
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*/
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'use strict';
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var NativeModules = require('NativeModules');
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var Promise = require('Promise');
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var RCTDeviceEventEmitter = require('RCTDeviceEventEmitter');
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var AccessibilityManager = NativeModules.AccessibilityManager;
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var VOICE_OVER_EVENT = 'voiceOverDidChange';
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var ANNOUNCEMENT_DID_FINISH_EVENT = 'announcementDidFinish';
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type ChangeEventName = $Enum<{
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change: string,
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announcementFinished: string
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}>;
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var _subscriptions = new Map();
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/**
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* Sometimes it's useful to know whether or not the device has a screen reader
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* that is currently active. The `AccessibilityInfo` API is designed for this
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* purpose. You can use it to query the current state of the screen reader as
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* well as to register to be notified when the state of the screen reader
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* changes.
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*
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* See http://facebook.github.io/react-native/docs/accessibilityinfo.html
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*/
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var AccessibilityInfo = {
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/**
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* Query whether a screen reader is currently enabled.
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*
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* Returns a promise which resolves to a boolean.
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* The result is `true` when a screen reader is enabledand `false` otherwise.
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*
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* See http://facebook.github.io/react-native/docs/accessibilityinfo.html#fetch
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*/
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fetch: function(): Promise {
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return new Promise((resolve, reject) => {
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AccessibilityManager.getCurrentVoiceOverState(
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resolve,
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reject
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);
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});
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},
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/**
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* Add an event handler. Supported events:
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*
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* - `change`: Fires when the state of the screen reader changes. The argument
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* to the event handler is a boolean. The boolean is `true` when a screen
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* reader is enabled and `false` otherwise.
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* - `announcementFinished`: iOS-only event. Fires when the screen reader has
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* finished making an announcement. The argument to the event handler is a
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* dictionary with these keys:
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* - `announcement`: The string announced by the screen reader.
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* - `success`: A boolean indicating whether the announcement was
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* successfully made.
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*
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* See http://facebook.github.io/react-native/docs/accessibilityinfo.html#addeventlistener
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*/
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addEventListener: function (
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eventName: ChangeEventName,
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handler: Function
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): Object {
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var listener;
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if (eventName === 'change') {
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listener = RCTDeviceEventEmitter.addListener(
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VOICE_OVER_EVENT,
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handler
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);
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} else if (eventName === 'announcementFinished') {
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listener = RCTDeviceEventEmitter.addListener(
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ANNOUNCEMENT_DID_FINISH_EVENT,
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handler
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);
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}
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_subscriptions.set(handler, listener);
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return {
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remove: AccessibilityInfo.removeEventListener.bind(null, eventName, handler),
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};
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},
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/**
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* Set accessibility focus to a react component.
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*
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* @platform ios
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*
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* See http://facebook.github.io/react-native/docs/accessibilityinfo.html#setaccessibilityfocus
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*/
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setAccessibilityFocus: function(
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reactTag: number
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): void {
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AccessibilityManager.setAccessibilityFocus(reactTag);
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},
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/**
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* Post a string to be announced by the screen reader.
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*
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* @platform ios
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*
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* See http://facebook.github.io/react-native/docs/accessibilityinfo.html#announceforaccessibility
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*/
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announceForAccessibility: function(
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announcement: string
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): void {
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AccessibilityManager.announceForAccessibility(announcement);
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},
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/**
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* Remove an event handler.
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*
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* See http://facebook.github.io/react-native/docs/accessibilityinfo.html#removeeventlistener
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*/
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removeEventListener: function(
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eventName: ChangeEventName,
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handler: Function
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): void {
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var listener = _subscriptions.get(handler);
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if (!listener) {
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return;
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}
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listener.remove();
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_subscriptions.delete(handler);
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},
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};
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module.exports = AccessibilityInfo;
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