webrtc-adapter/src/js/edge/edge_shim.js

A shim to insulate apps from WebRTC spec changes and browser prefix differences

/*
 *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree.
 */
 /* eslint-env node */
'use strict';

var utils = require('../utils');
var shimRTCPeerConnection = require('./rtcpeerconnection_shim');

module.exports = {
  shimGetUserMedia: require('./getusermedia'),
  shimPeerConnection: function(window) {
    var browserDetails = utils.detectBrowser(window);

    if (window.RTCIceGatherer) {
      // ORTC defines an RTCIceCandidate object but no constructor.
      // Not implemented in Edge.
      if (!window.RTCIceCandidate) {
        window.RTCIceCandidate = function(args) {
          return args;
        };
      }
      // ORTC does not have a session description object but
      // other browsers (i.e. Chrome) that will support both PC and ORTC
      // in the future might have this defined already.
      if (!window.RTCSessionDescription) {
        window.RTCSessionDescription = function(args) {
          return args;
        };
      }
      // this adds an additional event listener to MediaStrackTrack that signals
      // when a tracks enabled property was changed. Workaround for a bug in
      // addStream, see below. No longer required in 15025+
      if (browserDetails.version < 15025) {
        var origMSTEnabled = Object.getOwnPropertyDescriptor(
            window.MediaStreamTrack.prototype, 'enabled');
        Object.defineProperty(window.MediaStreamTrack.prototype, 'enabled', {
          set: function(value) {
            origMSTEnabled.set.call(this, value);
            var ev = new Event('enabled');
            ev.enabled = value;
            this.dispatchEvent(ev);
          }
        });
      }
    }

    // ORTC defines the DTMF sender a bit different.
    // https://github.com/w3c/ortc/issues/714
    if (window.RTCRtpSender && !('dtmf' in window.RTCRtpSender.prototype)) {
      Object.defineProperty(window.RTCRtpSender.prototype, 'dtmf', {
        get: function() {
          if (this._dtmf === undefined) {
            if (this.track.kind === 'audio') {
              this._dtmf = new window.RTCDtmfSender(this);
            } else if (this.track.kind === 'video') {
              this._dtmf = null;
            }
          }
          return this._dtmf;
        }
      });
    }

    window.RTCPeerConnection =
        shimRTCPeerConnection(window, browserDetails.version);
  },
  shimReplaceTrack: function(window) {
    // ORTC has replaceTrack -- https://github.com/w3c/ortc/issues/614
    if (window.RTCRtpSender &&
        !('replaceTrack' in window.RTCRtpSender.prototype)) {
      window.RTCRtpSender.prototype.replaceTrack =
          window.RTCRtpSender.prototype.setTrack;
    }
  }
};