67 lines
1.8 KiB
JavaScript
67 lines
1.8 KiB
JavaScript
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// @flow
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/**
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* An registry that dispatches hardware back button events for subscribers with a custom logic.
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*/
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class BackButtonRegistry {
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_listeners: Array<Function>;
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/**
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* Instantiates a new instance of the registry.
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*/
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constructor() {
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this._listeners = [];
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}
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/**
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* Adds a listener to the registry.
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*
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* NOTE: Due to the different order of component mounts, we allow a component to register
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* its listener to the top of the list, so then that will be invoked before other, 'non-top'
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* listeners. For example a 'non-top' listener can be the one that puts the app into PiP mode,
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* while a 'top' listener is the one that closes a modal in a conference.
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*
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* @param {Function} listener - The listener function.
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* @param {boolean?} top - If true, the listener will be put on the top (eg for modal-like components).
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* @returns {void}
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*/
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addListener(listener: Function, top: boolean = false) {
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if (top) {
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this._listeners.splice(0, 0, listener);
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} else {
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this._listeners.push(listener);
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}
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}
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/**
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* Removes a listener from the registry.
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*
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* @param {Function} listener - The listener to remove.
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* @returns {void}
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*/
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removeListener(listener: Function) {
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this._listeners = this._listeners.filter(f => f !== listener);
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}
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onHardwareBackPress: () => boolean
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/**
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* Callback for the back button press event.
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*
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* @returns {boolean}
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*/
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onHardwareBackPress() {
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for (const listener of this._listeners) {
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const result = listener();
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if (result === true) {
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return true;
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}
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}
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return false;
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}
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}
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export default new BackButtonRegistry();
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