feat: Method named getNumActiveSimulcastLayers & event to LocalTrack …

…for constraints changed (#35)

* fix: add a method named getNumActiveSimulcastLayers & event to LocalTrack for constraints changed

* fix: add related ut cases

* fix: minor errors in unit test

---------

Co-authored-by: Brown Zhang <[email protected]>

src/media/local-track.spec.ts

@@ -62,3 +62,24 @@ describe('LocalTrack', () => {
     expect(constraints).toStrictEqual({ autoGainControl: true });
   });
 });
+
+describe('LocalTrack getNumActiveSimulcastLayers', () => {
+  it('activeSimulcastLayers returns 3 if video height greater than 360', () => {
+    expect.hasAssertions();
+    const mockStream = createMockedStream(720);
+    const localTrack = new TestLocalTrack(mockStream);
+    expect(localTrack.getNumActiveSimulcastLayers()).toBe(3);
+  });
+  it('activeSimulcastLayers returns 2 if video height greater than 180 but less(equals) than 360', () => {
+    expect.hasAssertions();
+    const mockStream = createMockedStream(360);
+    const localTrack = new TestLocalTrack(mockStream);
+    expect(localTrack.getNumActiveSimulcastLayers()).toBe(2);
+  });
+  it('activeSimulcastLayers returns 1 if video height less(equals) than 180', () => {
+    expect.hasAssertions();
+    const mockStream = createMockedStream(180);
+    const localTrack = new TestLocalTrack(mockStream);
+    expect(localTrack.getNumActiveSimulcastLayers()).toBe(1);
+  });
+});

src/media/local-track.ts

@@ -17,6 +17,10 @@ export enum LocalTrackEvents {
    * Fires when there has been a change in the underlying track.
    */
   UnderlyingTrackChange = 'underlying-track-change',
+  /**
+   * Fires when the applyConstraints() has been called for the track.
+   */
+  TrackConstraintsChange = 'track-constraints-change',
 }
 
 export interface TrackState {
@@ -44,6 +48,7 @@ export interface TrackEvents extends EventMap {
   [LocalTrackEvents.Muted]: (event: TrackMuteEvent) => void;
   [LocalTrackEvents.PublishedStateUpdate]: (event: TrackPublishEvent) => void;
   [LocalTrackEvents.UnderlyingTrackChange]: () => void;
+  [LocalTrackEvents.TrackConstraintsChange]: () => void;
 }
 
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
@@ -276,7 +281,10 @@ export abstract class LocalTrack extends EventEmitter<TrackEvents> {
    */
   async applyConstraints(constraints?: MediaTrackConstraints): Promise<void> {
     logger.log(`Applying constraints to local track:`, constraints);
-    return this.underlyingTrack.applyConstraints(constraints);
+    const ret = this.underlyingTrack.applyConstraints(constraints).then(() => {
+      this.emit(LocalTrackEvents.TrackConstraintsChange);
+    });
+    return ret;
   }
 
   /**
@@ -296,4 +304,25 @@ export abstract class LocalTrack extends EventEmitter<TrackEvents> {
   getSettings(): MediaTrackSettings {
     return this.underlyingTrack.getSettings();
   }
+
+  /**
+   * Check the resolution and then return how many layers will be active.
+   *
+   * @returns The active layers count.
+   */
+  getNumActiveSimulcastLayers(): number {
+    let activeSimulcastLayersNumber = 0;
+    if (this.trackState.type === 'audio') {
+      return activeSimulcastLayersNumber;
+    }
+    const videoHeight = this.underlyingTrack.getSettings().height;
+    if ((videoHeight as number) <= 180) {
+      activeSimulcastLayersNumber = 1;
+    } else if ((videoHeight as number) <= 360) {
+      activeSimulcastLayersNumber = 2;
+    } else {
+      activeSimulcastLayersNumber = 3;
+    }
+    return activeSimulcastLayersNumber;
+  }
 }

src/mocks/media-stream-track-stub.ts

@@ -26,7 +26,9 @@ class MediaStreamTrackStub {
    */
   stop(): void {}
 
-  applyConstraints(constraints?: MediaTrackConstraints): void {}
+  applyConstraints(constraints?: MediaTrackConstraints): Promise<void> {
+    return Promise.resolve();
+  }
 
   getConstraints(): MediaTrackConstraints {
     return {} as MediaTrackConstraints;

src/util/test-utils.ts

@@ -8,11 +8,12 @@ jest.mock('../mocks/media-stream-track-stub');
 /**
  * Create a mocked stream with a mocked MediaStreamTrack.
  *
+ * @param videoHeight - Video height.
  * @returns A Mocked MediaStreamStub type coerced to a MediaStream.
  */
-export const createMockedStream = (): MediaStream => {
+export const createMockedStream = (videoHeight = 360): MediaStream => {
   // eslint-disable-next-line no-use-before-define
-  return createMockedStreamWithSize(640, 480);
+  return createMockedStreamWithSize((videoHeight * 16) / 9, videoHeight);
 };
 
 /**
@@ -32,6 +33,7 @@ export const createMockedStreamWithSize = (width: number, height: number): Media
   });
   track.applyConstraints.mockImplementation((constraints?: MediaTrackConstraints) => {
     track.constraints = constraints || {};
+    return Promise.resolve();
   });
   track.getConstraints.mockImplementation(() => {
     return track.constraints;