From a2c6ab66946d547e649276523f38270d373d7e64 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?H=C3=A5var=20Aamb=C3=B8=20Fosstveit?= <havar@fosstveit.net>
Date: Sun, 4 Mar 2018 12:51:28 +0100
Subject: [PATCH] Added class to handle the differences in screen sharing
 between browsers.

---
 app/lib/ScreenShare.js | 197 +++++++++++++++++++++++++++++++++++++++++
 app/lib/utils.js       |  19 ++++
 2 files changed, 216 insertions(+)
 create mode 100644 app/lib/ScreenShare.js

diff --git a/app/lib/ScreenShare.js b/app/lib/ScreenShare.js
new file mode 100644
index 0000000..b598bc6
--- /dev/null
+++ b/app/lib/ScreenShare.js
@@ -0,0 +1,197 @@
+import { getBrowserType } from './utils';
+
+class ChromeScreenShare
+{
+	constructor()
+	{
+		this._stream = null;
+	}
+
+	start(options = { })
+	{
+		const state = this;
+
+		return new Promise((resolve, reject) =>
+		{
+			window.addEventListener('message', _onExtensionMessage, false);
+			window.postMessage({ type: 'getStreamId' }, '*');
+
+			function _onExtensionMessage({ data })
+			{
+				if (data.type !== 'gotStreamId')
+				{
+					return;
+				}
+
+				const constraints = state._toConstraints(options, data.streamId);
+
+				navigator.mediaDevices.getUserMedia(constraints)
+					.then((stream) =>
+					{
+						window.removeEventListener('message', _onExtensionMessage);
+
+						state._stream = stream;
+						resolve(stream);
+					})
+					.catch((err) =>
+					{
+						window.removeEventListener('message', _onExtensionMessage);
+
+						reject(err);
+					});
+			}
+		});
+	}
+
+	stop()
+	{
+		if (this._stream instanceof MediaStream === false)
+		{
+			return;
+		}
+
+		this._stream.getTracks().forEach((track) => track.stop());
+		this._stream = null;
+	}
+
+	isScreenShareAvailable()
+	{
+		if ('__multipartyMeetingScreenShareExtensionAvailable__' in window)
+		{
+			return true;
+		}
+
+		return false;
+	}
+
+	_toConstraints(options, streamId)
+	{
+		const constraints = {
+			video : {
+				mandatory : {
+					chromeMediaSource   : 'desktop',
+					chromeMediaSourceId : streamId
+				},
+				optional : [ {
+					googTemporalLayeredScreencast : true
+				} ]
+			},
+			audio : false
+		};
+
+		if (isFinite(options.width))
+		{
+			constraints.video.mandatory.maxWidth = options.width;
+			constraints.video.mandatory.minWidth = options.width;
+		}
+		if (isFinite(options.height))
+		{
+			constraints.video.mandatory.maxHeight = options.height;
+			constraints.video.mandatory.minHeight = options.height;
+		}
+		if (isFinite(options.frameRate))
+		{
+			constraints.video.mandatory.maxFrameRate = options.frameRate;
+			constraints.video.mandatory.minFrameRate = options.frameRate;
+		}
+
+		return constraints;
+	}
+}
+
+class FirefoxScreenShare
+{
+	constructor()
+	{
+		this._stream = null;
+	}
+
+	start(options = {})
+	{
+		const constraints = this._toConstraints(options);
+
+		return navigator.mediaDevices.getUserMedia(constraints)
+			.then((stream) =>
+			{
+				this._stream = stream;
+
+				return Promise.resolve(stream);
+			});
+	}
+
+	stop()
+	{
+		if (this._stream instanceof MediaStream === false)
+		{
+			return;
+		}
+
+		this._stream.getTracks().forEach((track) => track.stop());
+		this._stream = null;
+	}
+
+	isScreenShareAvailable()
+	{
+		return true;
+	}
+
+	_toConstraints(options)
+	{
+		const constraints = {
+			video : {
+				mediaSource : 'window'
+			},
+			audio : false
+		};
+
+		if ('mediaSource' in options)
+		{
+			constraints.video.mediaSource = options.mediaSource;
+		}
+		if (isFinite(options.width))
+		{
+			constraints.video.width = {
+				min : options.width,
+				max : options.width
+			};
+		}
+		if (isFinite(options.height))
+		{
+			constraints.video.height = {
+				min : options.height,
+				max : options.height
+			};
+		}
+		if (isFinite(options.frameRate))
+		{
+			constraints.video.frameRate = {
+				min : options.frameRate,
+				max : options.frameRate
+			};
+		}
+
+		return constraints;
+	}
+}
+
+export default class ScreenShare
+{
+	static create()
+	{
+		switch (getBrowserType())
+		{
+			case 'firefox':
+			{
+				return new FirefoxScreenShare();
+			}
+			case 'chrome':
+			{
+				return new ChromeScreenShare();
+			}
+			default:
+			{
+				return null;
+			}
+		}
+	}
+}
diff --git a/app/lib/utils.js b/app/lib/utils.js
index b36c7d4..91c8768 100644
--- a/app/lib/utils.js
+++ b/app/lib/utils.js
@@ -18,3 +18,22 @@ export function isMobile()
 {
 	return !mediaQueryDetectorElem.offsetParent;
 }
+
+export function getBrowserType()
+{
+	const ua = navigator.userAgent.toLowerCase();
+
+	// Firefox
+	if (ua.indexOf('firefox') !== -1)
+	{
+		return 'firefox';
+	}
+
+	// Chrome
+	if (ua.indexOf('chrome') !== -1 && ua.indexOf('edge') === -1)
+	{
+		return 'chrome';
+	}
+
+	return 'N/A';
+}