117 lines
3.2 KiB
JavaScript
117 lines
3.2 KiB
JavaScript
/**
|
|
* Copyright (c) Facebook, Inc. and its affiliates.
|
|
*
|
|
* This source code is licensed under the MIT license found in the
|
|
* LICENSE file in the root directory of this source tree.
|
|
*
|
|
* @flow
|
|
* @format
|
|
*/
|
|
|
|
'use strict';
|
|
|
|
import NativeDeviceEventManager from '../../Libraries/NativeModules/specs/NativeDeviceEventManager';
|
|
import RCTDeviceEventEmitter from '../EventEmitter/RCTDeviceEventEmitter';
|
|
|
|
const DEVICE_BACK_EVENT = 'hardwareBackPress';
|
|
|
|
type BackPressEventName = 'backPress' | 'hardwareBackPress';
|
|
|
|
const _backPressSubscriptions = [];
|
|
|
|
RCTDeviceEventEmitter.addListener(DEVICE_BACK_EVENT, function() {
|
|
for (let i = _backPressSubscriptions.length - 1; i >= 0; i--) {
|
|
if (_backPressSubscriptions[i]()) {
|
|
return;
|
|
}
|
|
}
|
|
|
|
BackHandler.exitApp();
|
|
});
|
|
|
|
/**
|
|
* Detect hardware button presses for back navigation.
|
|
*
|
|
* Android: Detect hardware back button presses, and programmatically invoke the default back button
|
|
* functionality to exit the app if there are no listeners or if none of the listeners return true.
|
|
*
|
|
* tvOS: Detect presses of the menu button on the TV remote. (Still to be implemented:
|
|
* programmatically disable menu button handling
|
|
* functionality to exit the app if there are no listeners or if none of the listeners return true.)
|
|
*
|
|
* iOS: Not applicable.
|
|
*
|
|
* The event subscriptions are called in reverse order (i.e. last registered subscription first),
|
|
* and if one subscription returns true then subscriptions registered earlier will not be called.
|
|
*
|
|
* Example:
|
|
*
|
|
* ```javascript
|
|
* BackHandler.addEventListener('hardwareBackPress', function() {
|
|
* // this.onMainScreen and this.goBack are just examples, you need to use your own implementation here
|
|
* // Typically you would use the navigator here to go to the last state.
|
|
*
|
|
* if (!this.onMainScreen()) {
|
|
* this.goBack();
|
|
* return true;
|
|
* }
|
|
* return false;
|
|
* });
|
|
* ```
|
|
*/
|
|
type TBackHandler = {|
|
|
+exitApp: () => void,
|
|
+addEventListener: (
|
|
eventName: BackPressEventName,
|
|
handler: Function,
|
|
) => {remove: () => void, ...},
|
|
+removeEventListener: (
|
|
eventName: BackPressEventName,
|
|
handler: Function,
|
|
) => void,
|
|
|};
|
|
const BackHandler: TBackHandler = {
|
|
exitApp: function(): void {
|
|
if (!NativeDeviceEventManager) {
|
|
return;
|
|
}
|
|
|
|
NativeDeviceEventManager.invokeDefaultBackPressHandler();
|
|
},
|
|
|
|
/**
|
|
* Adds an event handler. Supported events:
|
|
*
|
|
* - `hardwareBackPress`: Fires when the Android hardware back button is pressed or when the
|
|
* tvOS menu button is pressed.
|
|
*/
|
|
addEventListener: function(
|
|
eventName: BackPressEventName,
|
|
handler: Function,
|
|
): {remove: () => void, ...} {
|
|
if (_backPressSubscriptions.indexOf(handler) === -1) {
|
|
_backPressSubscriptions.push(handler);
|
|
}
|
|
return {
|
|
remove: (): void => BackHandler.removeEventListener(eventName, handler),
|
|
};
|
|
},
|
|
|
|
/**
|
|
* Removes the event handler.
|
|
*/
|
|
removeEventListener: function(
|
|
eventName: BackPressEventName,
|
|
handler: Function,
|
|
): void {
|
|
if (_backPressSubscriptions.indexOf(handler) !== -1) {
|
|
_backPressSubscriptions.splice(
|
|
_backPressSubscriptions.indexOf(handler),
|
|
1,
|
|
);
|
|
}
|
|
},
|
|
};
|
|
|
|
module.exports = BackHandler;
|