Screen

Screen API requires node-webkit >= v0.10.2

Screen is an instance of EventEmitter object, and you're able to use Screen.on(...) to respond to native screen's events.

Screen is a singleton object, need to be initiated once by calling gui.Screen.Init()

Reference

Screen.Init()

Init the Screen singleton object, you only need to call this once

Screen.screens

Get the array of screen (number of screen connected to the computer)

screen has following structure:

screen {
// unique id for a screen
  id : int,

// physical screen resolution, can be negative, not necessarily start from 0,depending on screen arrangement
  bounds : {
    x : int,
    y : int,
    width : int,
    height : int
  },
 
// useable area within the screen bound
  work_area : {
    x : int,
    y : int,
    width : int,
    height : int
  },

  scaleFactor : float,
  isBuiltIn : bool,
  rotation : int,
  touchSupport : int
}

Screen.chooseDesktopMedia (array of DesktopCaptureSourceType sources, function callback)

Screen.chooseDesktopMedia requires nwjs >= v0.12.0
Screen sharing by selection; Currently only working in Windows and OSX and some linux distribution.

DesktopCaptureSourceType: "window" or "screen"
The callback parameter should be a function that looks like this: function(string streamId) {...};
returns false if the function fails to execute or existing chooseDesktopMedia is still active

Example:

var gui = require('nw.gui');
gui.Screen.Init(); // you only need to call this once
gui.Screen.chooseDesktopMedia(["window","screen"], 
  function(streamId) {
    var vid_constraint = {
      mandatory: {
        chromeMediaSource: 'desktop', 
        chromeMediaSourceId: streamId, 
        maxWidth: 1920, 
        maxHeight: 1080
      }, 
      optional:[]
    };
    navigator.webkitGetUserMedia({audio: false, video: constraint}, success_func, fallback_func);
  }
);

More info: https://github.com/nwjs/nw.js/issues/3077

Events

Following events can be listened by using Screen.on() function, for more information on how to receive events, you can visit EventEmitter.

displayBoundsChanged

emitted when the screen resolution, arrangement is changed, the callback is called with 1 argument `screen'

displayAdded

emitted when a new screen added, the callback is called with 1 argument `screen'

displayRemoved

emitted when existing screen removed, the callback is called with 1 argument `screen'

Synopsis

function ScreenToString(screen) {
  var string = "";
  string += "screen " + screen.id + " ";
  var rect = screen.bounds;
  string += "bound{" + rect.x + ", " + rect.y + ", " + rect.width + ", " + rect.height + "} ";
  rect = screen.work_area;
  string += "work_area{" + rect.x + ", " + rect.y + ", " + rect.width + ", " + rect.height + "} ";
  string += " scaleFactor: " + screen.scaleFactor;
  string += " isBuiltIn: " + screen.isBuiltIn;
  string += "<br>";
  return string;
}

//init must be called once during startup, before any function to gui.Screen can be called
gui.Screen.Init();
var string = "";
var screens = gui.Screen.screens;
// store all the screen information into string
for(var i=0; i<screens.length; i++) {
  string += ScreenToString(screens[i]);
}

var screenCB = {
  onDisplayBoundsChanged : function(screen) {
    var out = "OnDisplayBoundsChanged " + ScreenToString(screen);
  },

  onDisplayAdded : function(screen) {
    var out = "OnDisplayAdded " + ScreenToString(screen);
  },

  onDisplayRemoved : function(screen) {
    var out = "OnDisplayRemoved " + ScreenToString(screen);
  }
};

// listen to screen events
gui.Screen.on('displayBoundsChanged', screenCB.onDisplayBoundsChanged);
gui.Screen.on('displayAdded', screenCB.onDisplayAdded);
gui.Screen.on('displayRemoved', screenCB.onDisplayRemoved);