Small Fixes to WebRTC (#115)

* Make the robot browser headless

* Add comments

Author: amalnanavati

feedingwebapp/src/robot/RobotVideoStreams.jsx

@@ -6,6 +6,14 @@ import PropTypes from 'prop-types'
 import { ROBOT_COMPRESSED_IMG_TOPICS } from '../Pages/Constants'
 import VideoStream from './VideoStream'
 
+/**
+ * Renders all the video streams from the robot.
+ *
+ * NOTE: This page *must* be rendered on the robot, otherwise it will have
+ * incredible lag.
+ *
+ * @param {string} webrtcURL - The URL of the webrtc signalling server.
+ */
 function RobotVideoStreams(props) {
   console.log('Rendering RobotVideoStreams', ROBOT_COMPRESSED_IMG_TOPICS)
   return (

feedingwebapp/src/robot/VideoStream.jsx

@@ -7,6 +7,17 @@ import { useROS, subscribeToROSTopic, unsubscribeFromROSTopic } from '../ros/ros
 import { createPeerConnection } from '../webrtc/webrtc_helpers'
 import { REALSENSE_WIDTH, REALSENSE_HEIGHT } from '../Pages/Constants'
 
+/**
+ * Renders a video stream from the robot.
+ *
+ * NOTE: This page *must* be rendered on the robot, otherwise it will have
+ * incredible lag.
+ *
+ * @param {string} webrtcURL - The URL of the webrtc signalling server.
+ * @param {string} topic - The topic to subscribe to.
+ *
+ * @returns {object} A canvas element that displays the video stream.
+ */
 function VideoStream(props) {
   const canvas = useRef(null)
   const img = useMemo(() => document.createElement('img'), [])

feedingwebapp/src/webrtc/webrtc_helpers.js

@@ -2,6 +2,16 @@
 
 import axios from 'axios'
 
+/**
+ * Creates a peer connection to the given url and topic. This is intended to work with
+ * the server in server.js.
+ *
+ * @param {string} url The url of the server to connect to.
+ * @param {string} topic The topic to subscribe to.
+ * @param {function} onTrackAdded The callback function to call when a track is added.
+ * @param {function} onConnectionEnd The callback function to call when the connection ends.
+ * @returns {object} The RTCPeerConnection.
+ */
 export function createPeerConnection(url, topic, onTrackAdded, onConnectionEnd) {
   try {
     const peerConnection = new RTCPeerConnection({

feedingwebapp/start_robot_browser.js

@@ -21,7 +21,7 @@ if (process.argv.length > 2) {
   ///////////////////////////////////////////////
 
   const browser = await chromium.launch({
-    headless: false, // default is true
+    headless: true, // default is true
     ignoreHTTPSErrors: true, // avoid ERR_CERT_COMMON_NAME_INVALID
     defaultViewport: null,
     args: [