peer-stream.js

"5.0.2";

// Must be kept in sync with JavaScriptKeyCodeToFKey C++ array.
// special keycodes different from KeyboardEvent.keyCode
const SpecialKeyCodes = {
  Backspace: 8,
  ShiftLeft: 16,
  ControlLeft: 17,
  AltLeft: 18,
  ShiftRight: 253,
  ControlRight: 254,
  AltRight: 255,
};

// https://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/button
const MouseButton = {
  MainButton: 0, // Left button.
  AuxiliaryButton: 1, // Wheel button.
  SecondaryButton: 2, // Right button.
  FourthButton: 3, // Browser Back button.
  FifthButton: 4, // Browser Forward button.
};

// Must be kept in sync with PixelStreamingProtocol::EToClientMsg C++ enum.
const RECEIVE = {
  QualityControlOwnership: 0,
  Response: 1,
  Command: 2,
  FreezeFrame: 3,
  UnfreezeFrame: 4,
  VideoEncoderAvgQP: 5,
  LatencyTest: 6,
  InitialSettings: 7,
  FileExtension: 8,
  FileMimeType: 9,
  FileContents: 10,
};

// Must be kept in sync with PixelStreamingProtocol::EToUE4Msg C++ enum.
const SEND = {
  /*
   * Control Messages. Range = 0..49.
   */
  IFrameRequest: 0,
  RequestQualityControl: 1,
  FpsRequest: 2,
  AverageBitrateRequest: 3,
  StartStreaming: 4,
  StopStreaming: 5,
  LatencyTest: 6,
  RequestInitialSettings: 7,
  /*
   * Input Messages. Range = 50..89.
   */

  // Generic Input Messages. Range = 50..59.
  UIInteraction: 50,
  Command: 51,

  // Keyboard Input Message. Range = 60..69.
  KeyDown: 60,
  KeyUp: 61,
  KeyPress: 62,

  // Mouse Input Messages. Range = 70..79.
  MouseEnter: 70,
  MouseLeave: 71,
  MouseDown: 72,
  MouseUp: 73,
  MouseMove: 74,
  MouseWheel: 75,

  // Touch Input Messages. Range = 80..89.
  TouchStart: 80,
  TouchEnd: 81,
  TouchMove: 82,

  // Gamepad Input Messages. Range = 90..99
  GamepadButtonPressed: 90,
  GamepadButtonReleased: 91,
  GamepadAnalog: 92,
};

class PeerStream extends HTMLVideoElement {
  constructor(...params) {
    super(...params);

    window.ps = this;

    this.ws = { send() {}, close() {} }; // WebSocket
    this.pc = { close() {} }; // RTCPeerConnection

    this.setupVideo();
    this.registerKeyboardEvents();
    this.registerMouseHoverEvents();
    this.registerFakeMouseEvents();

    document.addEventListener(
      "pointerlockchange",
      () => {
        if (document.pointerLockElement === this) {
          this.registerPointerlockEvents();
        } else {
          this.registerMouseHoverEvents();
        }
      },
      false
    );

    this.addEventListener("loadeddata", (e) => {
      this.style["aspect-ratio"] = this.videoWidth / this.videoHeight;
    });

    // this.setupPeerConnection();
  }

  // setupWebsocket
  async connectedCallback() {
    // This will happen each time the node is moved, and may happen before the element"s contents have been fully parsed. may be called once your element is no longer connected
    if (!this.isConnected) return;
    if (this.pc.connectionState === "connected" && this.dc.readyState === "open") {
      clearTimeout(this.disconnectTimer);
      // this.pc.restartIce();
      this.play();
      return;
    }

    this.setupPeerConnection();

    let signal = this.getAttribute("signal") || `ws://${location.hostname || "localhost"}:88/hello`;

    // await new Promise((res) => setTimeout(res, 1000));
    this.ws.close(1000);
    this.ws = new WebSocket(signal);

    this.ws.onerror = (e) => {
      console.log(e);
    };

    this.ws.onopen = async (e) => {
      console.info("✅ connected to", this.ws.url);

      clearInterval(this.ping);
      this.ping = setInterval(() => {
        this.ws.send("ping");
      }, 1000 * 50);
    };

    this.ws.onmessage = (e) => {
      this.onWebSocketMessage(e.data);
    };

    this.ws.onclose = (e) => {
      console.info("❌ WebSocket closed:", e.reason || e.code);
      clearInterval(this.ping);

      clearTimeout(this.reconnect);
      this.reconnect = setTimeout(() => this.connectedCallback(), 3000);
    };
  }

  disconnectedCallback() {
    // lifecycle binding
    this.disconnectTimer = setTimeout(() => {
      this.ws.close(1000);
      this.pc.close();
      console.log("❌ peer connection closing");
      // this.dc.close();
    }, 1000);
  }

  adoptedCallback() {}

  static observedAttributes = ["signal"];
  attributeChangedCallback(name, oldValue, newValue) {
    if (!this.isConnected) return;
    // fired before connectedCallback when startup
    this.ws.close(1000);
  }

  async onWebSocketMessage(msg) {
    try {
      msg = JSON.parse(msg);
    } catch {
      console.debug("↓↓", msg);
      return;
    }
    if (msg.type === "offer") {
      const offer = new RTCSessionDescription(msg);
      console.log("↓↓ offer", offer);

      await this.pc.setRemoteDescription(offer);

      // Setup a transceiver for getting UE video
      this.pc.addTransceiver("video", { direction: "recvonly" });

      const answer = await this.pc.createAnswer();
      await this.pc.setLocalDescription(answer);

      console.log("↑↑ answer", answer);
      this.ws.send(JSON.stringify(answer));

      for (let receiver of this.pc.getReceivers()) {
        receiver.playoutDelayHint = 0;
      }
    } else if (msg.type === "iceCandidate") {
      const candidate = new RTCIceCandidate(msg.candidate);
      console.log("↓↓ candidate:", candidate);
      await this.pc.addIceCandidate(candidate);
    } else if (msg.type === "answer") {
      // deprecated
    } else {
      console.warn("↓↓", msg);
    }
  }

  onDataChannelMessage(data) {
    data = new Uint8Array(data);
    const utf16 = new TextDecoder("utf-16");
    switch (data[0]) {
      case RECEIVE.VideoEncoderAvgQP: {
        this.VideoEncoderQP = +utf16.decode(data.slice(1));
        console.debug("↓↓ QP:", this.VideoEncoderQP);
        break;
      }
      case RECEIVE.Response: {
        // user custom message
        const detail = utf16.decode(data.slice(1));
        this.dispatchEvent(new CustomEvent("message", { detail }));
        console.info("↓↓", detail);
        break;
      }
      case RECEIVE.Command: {
        const command = JSON.parse(utf16.decode(data.slice(1)));
        console.info("↓↓ command:", command);
        if (command.command === "onScreenKeyboard") {
          console.info("You should setup a on-screen keyboard");
        }
        break;
      }
      case RECEIVE.FreezeFrame: {
        const size = new DataView(data.slice(1, 5).buffer).getInt32(0, true);
        const jpeg = data.slice(1 + 4);
        console.info("↓↓ freezed frame:", jpeg);
        break;
      }
      case RECEIVE.UnfreezeFrame: {
        console.info("↓↓ 【unfreeze frame】");
        break;
      }
      case RECEIVE.LatencyTest: {
        const latencyTimings = JSON.parse(utf16.decode(data.slice(1)));
        console.info("↓↓ latency timings:", latencyTimings);
        break;
      }
      case RECEIVE.QualityControlOwnership: {
        this.QualityControlOwnership = data[1] !== 0;
        console.info("↓↓ Quality Control Ownership:", this.QualityControlOwnership);
        break;
      }
      case RECEIVE.InitialSettings: {
        this.InitialSettings = JSON.parse(utf16.decode(data.slice(1)));
        console.log("↓↓ initial setting:", this.InitialSettings);
        break;
      }
      default: {
        console.error("↓↓ invalid data:", data);
      }
    }
  }

  setupVideo() {
    this.tabIndex = 0; // easy to focus..
    this.autofocus = true;
    this.playsInline = true;
    this.disablepictureinpicture = true;

    // Recently many browsers can only autoplay the videos with sound off
    this.muted = true;
    this.autoplay = true;

    // this.onsuspend
    // this.onresize
    // this.requestPointerLock();

    this.style["pointer-events"] = "none";
    this.style["object-fit"] = "fill";
  }

  setupDataChannel(e) {
    // See https://www.w3.org/TR/webrtc/#dom-rtcdatachannelinit for values (this is needed for Firefox to be consistent with Chrome.)
    // this.dc = this.pc.createDataChannel(label, { ordered: true });

    this.dc = e.channel;

    // Inform browser we would like binary data as an ArrayBuffer (FF chooses Blob by default!)
    this.dc.binaryType = "arraybuffer";

    this.dc.onopen = (e) => {
      console.log("✅ data channel connected");
      this.style.pointerEvents = "auto";

      setTimeout(() => {
        this.dc.send(new Uint8Array([SEND.RequestInitialSettings]));
        if (!this.QualityControlOwnership) {
          this.dc.send(new Uint8Array([SEND.RequestQualityControl]));
        }
      }, 500);
    };

    this.dc.onclose = (e) => {
      console.info("❌ data channel closed");
      this.style.pointerEvents = "none";
    };

    this.dc.onerror = (e) => {};

    this.dc.onmessage = (e) => {
      this.onDataChannelMessage(e.data);
    };
  }

  setupPeerConnection() {
    this.pc.close();
    this.pc = new RTCPeerConnection({
      sdpSemantics: "unified-plan",
      bundlePolicy: "balanced",
      // iceServers: [
      //   {
      //     urls: [
      //       "stun:stun.l.google.com:19302",
      //       "stun:stun1.l.google.com:19302",
      //       "stun:stun2.l.google.com:19302",
      //       "stun:stun3.l.google.com:19302",
      //       "stun:stun4.l.google.com:19302",
      //     ],
      //   },
      // ],
    });

    this.pc.ontrack = (e) => {
      console.log(`↓↓ ${e.track.kind} track:`, e);
      if (e.track.kind === "video") {
        this.srcObject = e.streams[0];
      } else if (e.track.kind === "audio") {
        this.audio = document.createElement("audio");
        this.audio.autoplay = true;
        this.audio.srcObject = e.streams[0];
      }
    };
    this.pc.onicecandidate = (e) => {
      // firefox
      if (e.candidate?.candidate) {
        console.log("↑↑ candidate:", e.candidate);
        this.ws.send(JSON.stringify({ type: "iceCandidate", candidate: e.candidate }));
      } else {
        // Notice that the end of negotiation is detected here when the event"s candidate property is null.
      }
    };

    // const setPoster = () =>
    //   (this.poster = `data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg"><style>text{font-size:7mm;fill:red;}</style>
    //     <text x="10" y="030"> Signal:      ${this.pc.signalingState}     </text>
    //     <text x="10" y="065"> Connect:     ${this.pc.connectionState}    </text>
    //     <text x="10" y="100"> ICE Gather:  ${this.pc.iceGatheringState}  </text>
    //     <text x="10" y="135"> ICE Connect: ${this.pc.iceConnectionState} </text>
    //   </svg>`);
    // this.pc.onsignalingstatechange =
    //   this.pc.onconnectionstatechange =
    //   this.pc.oniceconnectionstatechange =
    //   this.pc.onicegatheringstatechange =
    //     setPoster;

    this.pc.ondatachannel = (e) => {
      this.setupDataChannel(e);
    };
  }

  registerKeyboardEvents() {
    this.onkeydown = (e) => {
      this.dc.send(new Uint8Array([SEND.KeyDown, SpecialKeyCodes[e.code] || e.keyCode, e.repeat]));
      // whether to prevent browser"s default behavior when keyboard/mouse have inputs, like F1~F12 and Tab
      // e.preventDefault();
    };

    this.onkeyup = (e) => {
      this.dc.send(new Uint8Array([SEND.KeyUp, SpecialKeyCodes[e.code] || e.keyCode]));
      // e.preventDefault();
    };

    this.onkeypress = (e) => {
      const data = new DataView(new ArrayBuffer(3));
      data.setUint8(0, SEND.KeyPress);
      data.setUint16(1, SpecialKeyCodes[e.code] || e.keyCode, true);
      this.dc.send(data);
      // e.preventDefault();
    };
  }

  registerTouchEvents() {
    // We need to assign a unique identifier to each finger.
    // We do this by mapping each Touch object to the identifier.
    const fingers = [9, 8, 7, 6, 5, 4, 3, 2, 1, 0];
    const fingerIds = {};

    this.ontouchstart = (e) => {
      // Assign a unique identifier to each touch.
      for (const touch of e.changedTouches) {
        // remember touch
        const finger = fingers.pop();
        if (finger === undefined) {
          console.info("exhausted touch indentifiers");
        }
        fingerIds[touch.identifier] = finger;
      }
      this.emitTouchData(SEND.TouchStart, e.changedTouches, fingerIds);
      e.preventDefault();
    };

    this.ontouchend = (e) => {
      this.emitTouchData(SEND.TouchEnd, e.changedTouches, fingerIds);
      // Re-cycle unique identifiers previously assigned to each touch.
      for (const touch of e.changedTouches) {
        // forget touch
        fingers.push(fingerIds[touch.identifier]);
        delete fingerIds[touch.identifier];
      }
      e.preventDefault();
    };

    this.ontouchmove = (e) => {
      this.emitTouchData(SEND.TouchMove, e.touches, fingerIds);
      e.preventDefault();
    };
  }

  // touch as mouse
  registerFakeMouseEvents() {
    let finger = undefined;

    const { left, top } = this.getBoundingClientRect();

    this.ontouchstart = (e) => {
      if (finger === undefined) {
        const firstTouch = e.changedTouches[0];
        finger = {
          id: firstTouch.identifier,
          x: firstTouch.clientX - left,
          y: firstTouch.clientY - top,
        };
        // Hack: Mouse events require an enter and leave so we just enter and leave manually with each touch as this event is not fired with a touch device.
        this.onmouseenter(e);
        this.emitMouseDown(MouseButton.MainButton, finger.x, finger.y);
      }
      e.preventDefault();
    };

    this.ontouchend = (e) => {
      for (const touch of e.changedTouches) {
        if (touch.identifier === finger.id) {
          const x = touch.clientX - left;
          const y = touch.clientY - top;
          this.emitMouseUp(MouseButton.MainButton, x, y);
          // Hack: Manual mouse leave event.
          this.onmouseleave(e);
          finger = undefined;
          break;
        }
      }
      e.preventDefault();
    };

    this.ontouchmove = (e) => {
      for (const touch of e.touches) {
        if (touch.identifier === finger.id) {
          const x = touch.clientX - left;
          const y = touch.clientY - top;
          this.emitMouseMove(x, y, x - finger.x, y - finger.y);
          finger.x = x;
          finger.y = y;
          break;
        }
      }
      e.preventDefault();
    };
  }

  registerMouseHoverEvents() {
    this.registerMouseEnterAndLeaveEvents();

    this.onmousemove = (e) => {
      this.emitMouseMove(e.offsetX, e.offsetY, e.movementX, e.movementY);
      e.preventDefault();
    };

    this.onmousedown = (e) => {
      this.emitMouseDown(e.button, e.offsetX, e.offsetY);
      // e.preventDefault();
    };

    this.onmouseup = (e) => {
      this.emitMouseUp(e.button, e.offsetX, e.offsetY);
      // e.preventDefault();
    };

    // When the context menu is shown then it is safest to release the button which was pressed when the event happened. This will guarantee we will get at least one mouse up corresponding to a mouse down event. Otherwise the mouse can get stuck.
    // https://github.com/facebook/react/issues/5531
    this.oncontextmenu = (e) => {
      this.emitMouseUp(e.button, e.offsetX, e.offsetY);
      e.preventDefault();
    };

    this.onwheel = (e) => {
      this.emitMouseWheel(e.wheelDelta, e.offsetX, e.offsetY);
      e.preventDefault();
    };
  }

  registerPointerlockEvents() {
    this.registerMouseEnterAndLeaveEvents();

    console.info("mouse locked in, ESC to exit");

    const { clientWidth, clientHeight } = this;
    let x = clientWidth / 2;
    let y = clientHeight / 2;

    this.onmousemove = (e) => {
      x += e.movementX;
      y += e.movementY;
      x = (x + clientWidth) % clientWidth;
      y = (y + clientHeight) % clientHeight;

      this.emitMouseMove(x, y, e.movementX, e.movementY);
    };

    this.onmousedown = (e) => {
      this.emitMouseDown(e.button, x, y);
    };

    this.onmouseup = (e) => {
      this.emitMouseUp(e.button, x, y);
    };

    this.onwheel = (e) => {
      this.emitMouseWheel(e.wheelDelta, x, y);
    };
  }

  registerMouseEnterAndLeaveEvents() {
    this.onmouseenter = (e) => {
      this.dc.send(new Uint8Array([SEND.MouseEnter]));
    };

    this.onmouseleave = (e) => {
      this.dc.send(new Uint8Array([SEND.MouseLeave]));
    };
  }

  emitMouseMove(x, y, deltaX, deltaY) {
    const coord = this.normalize(x, y);
    deltaX = (deltaX * 65536) / this.clientWidth;
    deltaY = (deltaY * 65536) / this.clientHeight;
    const data = new DataView(new ArrayBuffer(9));
    data.setUint8(0, SEND.MouseMove);
    data.setUint16(1, coord.x, true);
    data.setUint16(3, coord.y, true);
    data.setInt16(5, deltaX, true);
    data.setInt16(7, deltaY, true);
    this.dc.send(data);
  }

  emitMouseDown(button, x, y) {
    const coord = this.normalize(x, y);
    const data = new DataView(new ArrayBuffer(6));
    data.setUint8(0, SEND.MouseDown);
    data.setUint8(1, button);
    data.setUint16(2, coord.x, true);
    data.setUint16(4, coord.y, true);
    this.dc.send(data);
  }

  emitMouseUp(button, x, y) {
    const coord = this.normalize(x, y);
    const data = new DataView(new ArrayBuffer(6));
    data.setUint8(0, SEND.MouseUp);
    data.setUint8(1, button);
    data.setUint16(2, coord.x, true);
    data.setUint16(4, coord.y, true);
    this.dc.send(data);
  }

  emitMouseWheel(delta, x, y) {
    const coord = this.normalize(x, y);
    const data = new DataView(new ArrayBuffer(7));
    data.setUint8(0, SEND.MouseWheel);
    data.setInt16(1, delta, true);
    data.setUint16(3, coord.x, true);
    data.setUint16(5, coord.y, true);
    this.dc.send(data);
  }

  emitTouchData(type, touches, fingerIds) {
    const data = new DataView(new ArrayBuffer(2 + 6 * touches.length));
    data.setUint8(0, type);
    data.setUint8(1, touches.length);
    let byte = 2;
    for (const touch of touches) {
      const x = touch.clientX - this.offsetLeft;
      const y = touch.clientY - this.offsetTop;

      const coord = this.normalize(x, y);
      data.setUint16(byte, coord.x, true);
      byte += 2;
      data.setUint16(byte, coord.y, true);
      byte += 2;
      data.setUint8(byte, fingerIds[touch.identifier], true);
      byte += 1;
      data.setUint8(byte, 255 * touch.force, true); // force is between 0.0 and 1.0 so quantize into byte.
      byte += 1;
    }
    this.dc.send(data);
  }

  // emit string
  emitMessage(msg, messageType = SEND.UIInteraction) {
    if (typeof msg !== "string") msg = JSON.stringify(msg);

    // Add the UTF-16 JSON string to the array byte buffer, going two bytes at a time.
    const data = new DataView(new ArrayBuffer(1 + 2 + 2 * msg.length));
    let byteIdx = 0;
    data.setUint8(byteIdx, messageType);
    byteIdx++;
    data.setUint16(byteIdx, msg.length, true);
    byteIdx += 2;
    for (const char of msg) {
      // charCodeAt() is UTF-16, codePointAt() is Unicode.
      data.setUint16(byteIdx, char.charCodeAt(0), true);
      byteIdx += 2;
    }
    this.dc.send(data);

    return 'sent';
  }

  normalize(x, y) {
    const normalizedX = x / this.clientWidth;
    const normalizedY = y / this.clientHeight;
    if (normalizedX < 0.0 || normalizedX > 1.0 || normalizedY < 0.0 || normalizedY > 1.0) {
      return {
        inRange: false,
        x: 65535,
        y: 65535,
      };
    } else {
      return {
        inRange: true,
        x: normalizedX * 65536,
        y: normalizedY * 65536,
      };
    }
  }

  debug(NodeJS) {
    // debugging the signalling server
    this.ws.send(JSON.stringify({ type: "debug", debug: NodeJS }));
    return true;
  }
}

customElements.define("peer-stream", PeerStream, { extends: "video" });