Split MediaViewModel into multiple files

src/state/media/LocalUserMediaViewModel.ts

@@ -0,0 +1,137 @@
+/*
+Copyright 2023, 2024 New Vector Ltd.
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import {
+  facingModeFromLocalTrack,
+  type LocalParticipant,
+  LocalVideoTrack,
+  TrackEvent,
+} from "livekit-client";
+import {
+  fromEvent,
+  map,
+  merge,
+  type Observable,
+  of,
+  startWith,
+  switchMap,
+} from "rxjs";
+import { logger } from "matrix-js-sdk/lib/logger";
+
+import { type Behavior } from "../Behavior";
+import {
+  type BaseUserMediaInputs,
+  type BaseUserMediaViewModel,
+  createBaseUserMedia,
+} from "./UserMediaViewModel";
+import { type ObservableScope } from "../ObservableScope";
+import { alwaysShowSelf } from "../../settings/settings";
+import { platform } from "../../Platform";
+import { type MediaDevices } from "../MediaDevices";
+
+export interface LocalUserMediaViewModel extends BaseUserMediaViewModel {
+  local: true;
+  /**
+   * Whether the video should be mirrored.
+   */
+  mirror$: Behavior<boolean>;
+  /**
+   * Whether to show this tile in a highly visible location near the start of
+   * the grid.
+   */
+  alwaysShow$: Behavior<boolean>;
+  setAlwaysShow: (value: boolean) => void;
+  switchCamera$: Behavior<(() => void) | null>;
+}
+
+export interface LocalUserMediaInputs extends Omit<
+  BaseUserMediaInputs,
+  "statsType"
+> {
+  participant$: Behavior<LocalParticipant | null>;
+  mediaDevices: MediaDevices;
+}
+
+export function createLocalUserMedia(
+  scope: ObservableScope,
+  { mediaDevices, ...inputs }: LocalUserMediaInputs,
+): LocalUserMediaViewModel {
+  const baseUserMedia = createBaseUserMedia(scope, {
+    ...inputs,
+    statsType: "outbound-rtp",
+  });
+
+  /**
+   * The local video track as an observable that emits whenever the track
+   * changes, the camera is switched, or the track is muted.
+   */
+  const videoTrack$: Observable<LocalVideoTrack | null> =
+    baseUserMedia.video$.pipe(
+      switchMap((v) => {
+        const track = v?.publication.track;
+        if (!(track instanceof LocalVideoTrack)) return of(null);
+        return merge(
+          // Watch for track restarts because they indicate a camera switch.
+          // This event is also emitted when unmuting the track object.
+          fromEvent(track, TrackEvent.Restarted).pipe(
+            startWith(null),
+            map(() => track),
+          ),
+          // When the track object is muted, reset it to null.
+          fromEvent(track, TrackEvent.Muted).pipe(map(() => null)),
+        );
+      }),
+    );
+
+  return {
+    ...baseUserMedia,
+    local: true,
+    mirror$: scope.behavior(
+      videoTrack$.pipe(
+        // Mirror only front-facing cameras (those that face the user)
+        map(
+          (track) =>
+            track !== null &&
+            facingModeFromLocalTrack(track).facingMode === "user",
+        ),
+      ),
+    ),
+    alwaysShow$: alwaysShowSelf.value$,
+    setAlwaysShow: alwaysShowSelf.setValue,
+    switchCamera$: scope.behavior(
+      platform === "desktop"
+        ? of(null)
+        : videoTrack$.pipe(
+            map((track) => {
+              if (track === null) return null;
+              const facingMode = facingModeFromLocalTrack(track).facingMode;
+              // If the camera isn't front or back-facing, don't provide a switch
+              // camera shortcut at all
+              if (facingMode !== "user" && facingMode !== "environment")
+                return null;
+              // Restart the track with a camera facing the opposite direction
+              return (): void =>
+                void track
+                  .restartTrack({
+                    facingMode: facingMode === "user" ? "environment" : "user",
+                  })
+                  .then(() => {
+                    // Inform the MediaDevices which camera was chosen
+                    const deviceId =
+                      track.mediaStreamTrack.getSettings().deviceId;
+                    if (deviceId !== undefined)
+                      mediaDevices.videoInput.select(deviceId);
+                  })
+                  .catch((e) =>
+                    logger.error("Failed to switch camera", facingMode, e),
+                  );
+            }),
+          ),
+    ),
+  };
+}