feat: add preferCurrentTab support for flutter web. (#305)

lib/src/track/local/local.dart

@@ -1,5 +1,6 @@
 import 'dart:async';
 
+import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 
 import 'package:flutter_webrtc/flutter_webrtc.dart' as rtc;
@@ -119,7 +120,7 @@ abstract class LocalTrack extends Track {
   static Future<rtc.MediaStream> createStream(
     LocalTrackOptions options,
   ) async {
-    final constraints = <String, dynamic>{
+    var constraints = <String, dynamic>{
       'audio': options is AudioCaptureOptions
           ? options.toMediaConstraintsMap()
           : options is ScreenShareCaptureOptions
@@ -132,6 +133,14 @@ abstract class LocalTrack extends Track {
 
     final rtc.MediaStream stream;
     if (options is ScreenShareCaptureOptions) {
+      if (kIsWeb) {
+        if (options.preferCurrentTab) {
+          constraints['preferCurrentTab'] = true;
+        }
+        if (options.selfBrowserSurface != null) {
+          constraints['selfBrowserSurface'] = options.selfBrowserSurface!;
+        }
+      }
       stream = await rtc.navigator.mediaDevices.getDisplayMedia(constraints);
     } else {
       // options is CameraVideoTrackOptions

lib/src/track/options.dart

@@ -84,11 +84,21 @@ class ScreenShareCaptureOptions extends VideoCaptureOptions {
   /// See instructions on how to setup your Broadcast Extension here:
   /// https://github.com/flutter-webrtc/flutter-webrtc/wiki/iOS-Screen-Sharing#broadcast-extension-quick-setup
   final bool useiOSBroadcastExtension;
+
+  // for browser only, if true, will capture screen audio.
   final bool captureScreenAudio;
 
+  /// for browser only, if true, will capture current tab.
+  final bool preferCurrentTab;
+
+  /// for browser only, include or exclude self browser surface.
+  final String? selfBrowserSurface;
+
   const ScreenShareCaptureOptions({
     this.useiOSBroadcastExtension = false,
     this.captureScreenAudio = false,
+    this.preferCurrentTab = true,
+    this.selfBrowserSurface,
     String? sourceId,
     double? maxFrameRate,
     VideoParameters params = VideoParametersPresets.screenShareH1080FPS15,
@@ -97,6 +107,8 @@ class ScreenShareCaptureOptions extends VideoCaptureOptions {
   ScreenShareCaptureOptions.from(
       {this.useiOSBroadcastExtension = false,
       this.captureScreenAudio = false,
+      this.preferCurrentTab = true,
+      this.selfBrowserSurface,
       required VideoCaptureOptions captureOptions})
       : super(params: captureOptions.params);
 
@@ -105,12 +117,16 @@ class ScreenShareCaptureOptions extends VideoCaptureOptions {
     VideoParameters? params,
     String? sourceId,
     double? maxFrameRate,
+    bool? preferCurrentTab,
+    String? selfBrowserSurface,
   }) =>
       ScreenShareCaptureOptions(
         captureScreenAudio: captureScreenAudio ?? this.captureScreenAudio,
         params: params ?? this.params,
         sourceId: sourceId ?? deviceId,
         maxFrameRate: maxFrameRate ?? this.maxFrameRate,
+        preferCurrentTab: preferCurrentTab ?? this.preferCurrentTab,
+        selfBrowserSurface: selfBrowserSurface ?? this.selfBrowserSurface,
       );
 
   @override