desktop-capturer.md

desktopCapturer

Access information about media sources that can be used to capture audio and video from the desktop using the navigator.webkitGetUserMedia API.

The following example shows how to capture video from a desktop window whose title is Electron:

// In the renderer process.
const {desktopCapturer} = require('electron')

desktopCapturer.getSources({types: ['window', 'screen']}, (error, sources) => {
  if (error) throw error
  for (let 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
          }
        }
      }, handleStream, handleError)
      return
    }
  }
})

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

function handleError (e) {
  console.log(e)
}

To capture video from a source provided by desktopCapturer the constraints passed to navigator.webkitGetUserMedia must include chromeMediaSource: 'desktop', and audio: false.

To capture both audio and video from the entire desktop the constraints passed to navigator.webkitGetUserMedia must include chromeMediaSource: 'screen', and audio: true, but should not include a chromeMediaSourceId constraint.

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 the media source thumbnail should be scaled to, defaults to {width: 150, height: 150}.
• callback Function

Starts gathering information about all available desktop media sources, and calls callback(error, sources) when finished.

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

• id String - The identifier of a window or screen that can be used as a chromeMediaSourceId constraint when calling navigator.webkitGetUserMedia. The format of the identifier will be window:XX or screen:XX, where XX is a random generated number.
• name String - A screen source will be named either Entire Screen or Screen <index>, while the name of a window source will match the window title.
• thumbnail NativeImage - A thumbnail image. Note: There is no guarantee that the size of the thumbnail is the same as the thumnbailSize specified in the options passed to desktopCapturer.getSources. The actual size depends on the scale of the screen or window.