102 lines
3.2 KiB
TypeScript
102 lines
3.2 KiB
TypeScript
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/*
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Copyright 2026 Element Software Ltd.
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SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
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Please see LICENSE in the repository root for full details.
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*/
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import { combineLatest, map, merge, of, Subject, switchMap } from "rxjs";
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import { type Behavior } from "./Behavior";
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import { type ObservableScope } from "./ObservableScope";
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import { accumulate } from "../utils/observable";
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/**
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* Controls for audio playback volume.
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*/
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export interface VolumeControls {
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/**
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* The volume to which the audio is set, as a scalar multiplier.
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*/
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playbackVolume$: Behavior<number>;
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/**
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* Whether playback of this audio is disabled.
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*/
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playbackMuted$: Behavior<boolean>;
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togglePlaybackMuted: () => void;
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adjustPlaybackVolume: (value: number) => void;
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commitPlaybackVolume: () => void;
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}
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interface VolumeControlsInputs {
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pretendToBeDisconnected$: Behavior<boolean>;
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/**
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* The callback to run to notify the module performing audio playback of the
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* requested volume.
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*/
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sink$: Behavior<(volume: number) => void>;
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}
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/**
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* Creates a set of controls for audio playback volume and syncs this with the
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* audio playback module for the duration of the scope.
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*/
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export function createVolumeControls(
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scope: ObservableScope,
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{ pretendToBeDisconnected$, sink$ }: VolumeControlsInputs,
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): VolumeControls {
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const toggleMuted$ = new Subject<"toggle mute">();
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const adjustVolume$ = new Subject<number>();
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const commitVolume$ = new Subject<"commit">();
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const playbackVolume$ = scope.behavior<number>(
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merge(toggleMuted$, adjustVolume$, commitVolume$).pipe(
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accumulate({ volume: 1, committedVolume: 1 }, (state, event) => {
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switch (event) {
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case "toggle mute":
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return {
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...state,
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volume: state.volume === 0 ? state.committedVolume : 0,
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};
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case "commit":
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// Dragging the slider to zero should have the same effect as
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// muting: keep the original committed volume, as if it were never
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// dragged
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return {
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...state,
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committedVolume:
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state.volume === 0 ? state.committedVolume : state.volume,
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};
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default:
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// Volume adjustment
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return { ...state, volume: event };
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}
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}),
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map(({ volume }) => volume),
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),
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);
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// Sync the requested volume with the audio playback module
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combineLatest([
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sink$,
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// The playback volume, taking into account whether we're supposed to
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// pretend that the audio stream is disconnected (since we don't necessarily
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// want that to modify the UI state).
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pretendToBeDisconnected$.pipe(
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switchMap((disconnected) => (disconnected ? of(0) : playbackVolume$)),
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),
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])
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.pipe(scope.bind())
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.subscribe(([sink, volume]) => sink(volume));
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return {
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playbackVolume$,
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playbackMuted$: scope.behavior<boolean>(
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playbackVolume$.pipe(map((volume) => volume === 0)),
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),
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togglePlaybackMuted: () => toggleMuted$.next("toggle mute"),
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adjustPlaybackVolume: (value: number) => adjustVolume$.next(value),
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commitPlaybackVolume: () => commitVolume$.next("commit"),
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};
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}
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