philnash/screen-capture

An exploration of screen capture in browsers.

Screen capture and sharing

This repo is an exploration of screen capture in browsers, including using screen capture streams in WebRTC sessions with Twilio Video.

You can read about these examples on the Twilio Blog:

• Screen capture in Google Chrome
• Screen capture in Firefox
• Screen sharing in a Twilio Video application

Chrome extension

In the /extension directory is a minimal implementation of a Chrome extension that will give access to streams from the chrome.desktopCapture API.

Screen capture in Chrome

In the /chrome directory is an HTML page that takes advantage of the extension and captures the desktop to show within a <video> element on the page.

Note

You will need to load your own version of the Chrome extension into your browser and replace YOUR_EXTENSION_ID_HERE with your own extension ID.

You will also need to serve the file from a local web server so that you can visit it on localhost.

Production Note

If you wish to deploy the Chrome extension to the Chrome web store you will need to update the extension's manifest.json to include your own site's URL in the externally_connectable.matches key. You can add more than one URL as this is an array. For example:

  "externally_connectable": {
    "matches": ["*://localhost/*", "https://yourdomain.com/*"]
  },

Screen capture in Firefox

In the /firefox directory is an HTML page that uses the mediaDevices API with a mediaSource to indicate whether to capture the screen or a window.

Note

You will need to load this demo over HTTPS, even locally. You can do so by configuring a local web server with a self signed certificate or by setting up ngrok and using the HTTPS URL that it generates.

Video Chat example

In the /video-chat directory is a Twilio Video powered video chat application. To test this out you will need Node.js installed. cd to the video-chat directory and install the dependencies from npm.

cd video-chat
npm install

You will also need to configure the application by setting some environment variables. Copy the .env.example file to .env and fill in:

• Your Twilio Account Sid from your Twilio console
• A Twilio API Key and API Secret available from the API Keys section of the Twilio console

If you are using Chrome, make sure you have installed the extension from the extension directory. Find the getUserScreen function in video-chat/src/index.js and replace YOUR_EXTENSION_ID with the extension ID.

Run the application with:

npm start

If you are using Firefox, use ngrok to set up a tunnel to your localhost on port 3000.

Visit the application at localhost:3000 (or your ngrok URL). Enter your name and then enter a room name. Open another browser and do the same and you will be in a video chat. Click the share screen button and you will be shown a permissions dialog. Choose the screen you want to share and accept the permissions and your screen will appear in the other video chat.