electron/docs/api/desktop-capturer.md

desktopCapturer

List getUserMedia sources for capturing audio, video, and images from a microphone, camera, or screen.

// In the renderer process.
var desktopCapturer = require('electron').desktopCapturer;

desktopCapturer.getSources({types: ['window', 'screen']}, function(error, sources) {
  if (error) throw error;
  for (var i = 0; i < sources.length; ++i) {
    if (sources[i].name == "Electron") {
      navigator.webkitGetUserMedia({
        audio: false,
        video: {
          mandatory: {
            chromeMediaSource: 'desktop',
            chromeMediaSourceId: sources[i].id,
            minWidth: 1280,
            maxWidth: 1280,
            minHeight: 720,
            maxHeight: 720
          }
        }
      }, gotStream, getUserMediaError);
      return;
    }
  }
});

function gotStream(stream) {
  document.querySelector('video').src = URL.createObjectURL(stream);
}

function getUserMediaError(e) {
  console.log('getUserMediaError');
}

When creating a constraints object for the navigator.webkitGetUserMedia call, if you are using a source from desktopCapturer your chromeMediaSource must be set to "desktop" and your audio must be set to false.

If you wish to capture the audio and video from the entire desktop you can set chromeMediaSource to "screen" and audio to true. When using this method you cannot specify a chromeMediaSourceId.

Methods

The desktopCapturer module has the following methods:

desktopCapturer.getSources(options, callback)

• options Object
  • types Array - An array of String that lists the types of desktop sources to be captured, available types are screen and window.
  • thumbnailSize Object (optional) - The suggested size that thumbnail should be scaled, it is {width: 150, height: 150} by default.
• callback Function

Starts a request to get all desktop sources, callback will be called with callback(error, sources) when the request is completed.

The sources is an array of Source objects, each Source represents a captured screen or individual window, and has following properties:

• id String - The id of the captured window or screen used in navigator.webkitGetUserMedia. The format looks like window:XX or screen:XX where XX is a random generated number.
• name String - The described name of the capturing screen or window. If the source is a screen, the name will be Entire Screen or Screen <index>; if it is a window, the name will be the window's title.
• thumbnail NativeImage - A thumbnail native image.

Note: There is no guarantee that the size of source.thumbnail is always the same as the thumnbailSize in options. It also depends on the scale of the screen or window.