Implement screen sharing

src/room/InCallView.tsx

@@ -116,8 +116,6 @@ import ringtoneOgg from "../sound/ringtone.ogg?url";
 import { ConnectionLostError } from "../utils/errors.ts";
 import { useTrackProcessorObservable$ } from "../livekit/TrackProcessorContext.tsx";
 
-const canScreenshare = "getDisplayMedia" in (navigator.mediaDevices ?? {});
-
 const maxTapDurationMs = 400;
 
 export interface ActiveCallProps
@@ -224,7 +222,7 @@ export const InCallView: FC<InCallViewProps> = ({
   // Merge the refs so they can attach to the same element
   const containerRef = useMergedRefs(containerRef1, containerRef2);
 
-  const { hideScreensharing, showControls } = useUrlParams();
+  const { showControls } = useUrlParams();
 
   const muteAllAudio = useBehavior(muteAllAudio$);
   // Call pickup state and display names are needed for waiting overlay/sounds
@@ -299,6 +297,7 @@ export const InCallView: FC<InCallViewProps> = ({
   const showFooter = useBehavior(vm.showFooter$);
   const earpieceMode = useBehavior(vm.earpieceMode$);
   const audioOutputSwitcher = useBehavior(vm.audioOutputSwitcher$);
+  const sharingScreen = useBehavior(vm.sharingScreen$);
 
   // We need to set the proper timings on the animation based upon the sound length.
   const ringDuration = pickupPhaseAudio?.soundDuration["waiting"] ?? 1;
@@ -742,18 +741,6 @@ export const InCallView: FC<InCallViewProps> = ({
 
   const allLivekitRooms = useBehavior(vm.allLivekitRooms$);
   const memberships = useBehavior(vm.memberships$);
-  const toggleScreensharing = useCallback(() => {
-    // TODO-MULTI-SFU implement screensharing
-    throw new Error("TODO-MULTI-SFU");
-    // localParticipant
-    //   .setScreenShareEnabled(!isScreenShareEnabled, {
-    //     audio: true,
-    //     selfBrowserSurface: "include",
-    //     surfaceSwitching: "include",
-    //     systemAudio: "include",
-    //   })
-    //   .catch(logger.error);
-  }, []);
 
   const buttons: JSX.Element[] = [];
 
@@ -775,13 +762,13 @@ export const InCallView: FC<InCallViewProps> = ({
       data-testid="incall_videomute"
     />,
   );
-  if (canScreenshare && !hideScreensharing) {
+  if (vm.toggleScreenSharing !== null) {
     buttons.push(
       <ShareScreenButton
         key="share_screen"
         className={styles.shareScreen}
-        enabled={false} // TODO-MULTI-SFU
-        onClick={toggleScreensharing}
+        enabled={sharingScreen}
+        onClick={vm.toggleScreenSharing}
         onTouchEnd={onControlsTouchEnd}
         data-testid="incall_screenshare"
       />,

src/state/CallViewModel.ts

@@ -15,6 +15,7 @@ import {
   type LocalParticipant,
   ParticipantEvent,
   type RemoteParticipant,
+  type Participant,
 } from "livekit-client";
 import E2EEWorker from "livekit-client/e2ee-worker?worker";
 import {
@@ -341,18 +342,7 @@ class UserMedia {
 
     this.presenter$ = this.scope.behavior(
       this.participant$.pipe(
-        switchMap(
-          (p) =>
-            (p &&
-              observeParticipantEvents(
-                p,
-                ParticipantEvent.TrackPublished,
-                ParticipantEvent.TrackUnpublished,
-                ParticipantEvent.LocalTrackPublished,
-                ParticipantEvent.LocalTrackUnpublished,
-              ).pipe(map((p) => p.isScreenShareEnabled))) ??
-            of(false),
-        ),
+        switchMap((p) => (p === undefined ? of(false) : sharingScreen$(p))),
       ),
     );
   }
@@ -433,7 +423,19 @@ function getRoomMemberFromRtcMember(
   return { id, member };
 }
 
+function sharingScreen$(p: Participant): Observable<boolean> {
+  return observeParticipantEvents(
+    p,
+    ParticipantEvent.TrackPublished,
+    ParticipantEvent.TrackUnpublished,
+    ParticipantEvent.LocalTrackPublished,
+    ParticipantEvent.LocalTrackUnpublished,
+  ).pipe(map((p) => p.isScreenShareEnabled));
+}
+
 export class CallViewModel extends ViewModel {
+  private readonly urlParams = getUrlParams();
+
   private readonly livekitAlias = getLivekitAlias(this.matrixRTCSession);
 
   private readonly livekitE2EEKeyProvider = getE2eeKeyProvider(
@@ -1850,6 +1852,37 @@ export class CallViewModel extends ViewModel {
     filter((v) => v.playSounds),
   );
 
+  /**
+   * Whether we are sharing our screen.
+   */
+  public readonly sharingScreen$ = this.scope.behavior(
+    from(this.localConnection).pipe(
+      switchMap((c) => sharingScreen$(c.livekitRoom.localParticipant)),
+      startWith(false),
+    ),
+  );
+
+  /**
+   * Callback for toggling screen sharing. If null, screen sharing is not
+   * available.
+   */
+  public readonly toggleScreenSharing =
+    "getDisplayMedia" in (navigator.mediaDevices ?? {}) &&
+    !this.urlParams.hideScreensharing
+      ? (): void =>
+          void this.localConnection.then(
+            (c) =>
+              void c.livekitRoom.localParticipant
+                .setScreenShareEnabled(!this.sharingScreen$.value, {
+                  audio: true,
+                  selfBrowserSurface: "include",
+                  surfaceSwitching: "include",
+                  systemAudio: "include",
+                })
+                .catch(logger.error),
+          )
+      : null;
+
   public constructor(
     // A call is permanently tied to a single Matrix room
     private readonly matrixRTCSession: MatrixRTCSession,
@@ -1913,7 +1946,7 @@ export class CallViewModel extends ViewModel {
     });
 
     this.leave$.pipe(this.scope.bind()).subscribe((reason) => {
-      const { confineToRoom } = getUrlParams();
+      const { confineToRoom } = this.urlParams;
       leaveRTCSession(this.matrixRTCSession, "user")
         // Only sends matrix leave event. The Livekit session will disconnect once the ActiveCall-view unmounts.
         .then(() => {