Taking a screenshot

The previously created static prototype may look fancy, but is not of much use. We need a service capable of taking screenshots and recording screencasts.

If it was about a screenshot of the application window, we would simply use the API on NW.js:

import * as fs from "fs"; 
function takeScreenshot( filePath ){ 
  appWindow.capturePage(( img ) => { 
    fs.writeFileSync( filePath, img, "base64" ); 
  }, { 
    format : "png", 
    datatype : "raw" 
  }); 
} 

But we need a screenshot of the screen and, therefore, we have to get access to display input. W3C includes a specification draft, "Media Capture and Streams" (http://bit.ly/2qTtLXX), which describes an API to capture displayed media (mediaDevices.getDisplayMedia). Unfortunately, at the time of writing, it's not yet supported in NW.js or, to be honest,...