openreplay/frontend/app/player/web/assist/LocalStream.ts

declare global {
  interface HTMLCanvasElement {
    captureStream(frameRate?: number): MediaStream;
  }
}

function dummyTrack(): MediaStreamTrack {
  const canvas = document.createElement('canvas'); // , { width: 0, height: 0})
  canvas.width = canvas.height = 2; // Doesn't work when 1 (?!)
  const ctx = canvas.getContext('2d');
  ctx?.fillRect(0, 0, canvas.width, canvas.height);
  requestAnimationFrame(function draw() {
    ctx?.fillRect(0, 0, canvas.width, canvas.height);
    requestAnimationFrame(draw);
  });
  // Also works. Probably it should be done once connected.
  // setTimeout(() => { ctx?.fillRect(0,0, canvas.width, canvas.height) }, 4000)
  return canvas.captureStream(60).getTracks()[0];
}

export function RequestLocalStream(): Promise<LocalStream> {
  return navigator.mediaDevices
    .getUserMedia({ audio: true })
    .then((aStream) => {
      const aTrack = aStream.getAudioTracks()[0];
      if (!aTrack) {
        throw new Error('No audio tracks provided');
      }
      return new _LocalStream(aTrack);
    });
}

class _LocalStream {
  private mediaRequested: boolean = false;

  readonly stream: MediaStream;

  private readonly vdTrack: MediaStreamTrack;

  constructor(aTrack: MediaStreamTrack) {
    this.vdTrack = dummyTrack();
    this.stream = new MediaStream([aTrack, this.vdTrack]);
  }

  toggleVideo(): Promise<boolean> {
    if (!this.mediaRequested) {
      return navigator.mediaDevices
        .getUserMedia({ video: true })
        .then((vStream) => {
          const vTrack = vStream.getVideoTracks()[0];
          if (!vTrack) {
            throw new Error('No video track provided');
          }
          this.stream.addTrack(vTrack);
          this.stream.removeTrack(this.vdTrack);
          this.mediaRequested = true;
          if (this.onVideoTrackCb) {
            this.onVideoTrackCb(vTrack);
          }
          return true;
        })
        .catch((e) => {
          // TODO: log
          console.error(e);
          return false;
        });
    }
    let enabled = true;
    this.stream.getVideoTracks().forEach((track) => {
      track.enabled = enabled = enabled && !track.enabled;
    });
    return Promise.resolve(enabled);
  }

  toggleAudio(): boolean {
    let enabled = true;
    this.stream.getAudioTracks().forEach((track) => {
      track.enabled = enabled = enabled && !track.enabled;
    });
    return enabled;
  }

  private onVideoTrackCb: ((t: MediaStreamTrack) => void) | null = null;

  onVideoTrack(cb: (t: MediaStreamTrack) => void) {
    this.onVideoTrackCb = cb;
  }

  stop() {
    this.stream.getTracks().forEach((t) => t.stop());
  }
}

export type LocalStream = InstanceType<typeof _LocalStream>;