[FCE-4028] Add a camera switch to the example.

AGENTS.md

@@ -65,6 +65,7 @@ Run analyze, format and tests before every commit.
 | `lib/src/stats/` | periodic stats report |
 | `lib/src/livestream/` | WHIP/WHEP over plain HTTP, independent of the room connection |
 | `lib/src/audio_output/`, `lib/src/background/` | Dart side of the SDK's native plugin: audio routing, Android foreground service, iOS CallKit |
+| `lib/src/video/` | `RTCView`, `cameraDevices`, and `selectCamera`. May import `flutter_webrtc` (`test/import_boundary_test.dart`) |
 | `lib/src/models/`, `wire.dart`, `logger.dart`, `version.dart` | public immutable types and shared helpers |
 | `lib/src/fishjam_client.dart`, `lib/src/livestream_api.dart`, `lib/fishjam_client.dart` | the public facade; wiring and type conversion only |
 | `lib/src/connectivity_network_source.dart` | the `NetworkSource` (`signaling/network_source.dart`) on `connectivity_plus`; the only file that imports it |

SPEC.md

@@ -743,7 +743,6 @@ when it joins and stops them when it leaves.
 - The app adds `audio` and `voip` to `UIBackgroundModes`. Out of scope: VoIP push, incoming calls, answering,
   ring timeouts.
 
-
 ## 20d. Picture-in-picture
 
 `PictureInPictureView` renders a `MediaStream` and offers its first video track for picture-in-picture (PiP),
@@ -817,6 +816,18 @@ native plugin over the method channel `io.fishjam.client/pip` and the event chan
 - When there is no video track, the app and the window both draw `fallbackLabel` on
   `fallbackBackgroundColor` in `fallbackTextColor` (D24).
 
+## 20e. Camera preview
+
+`RTCView` renders a `MediaStream`. `mirror` (default `false`) mirrors that picture. `objectFit` is `contain` (default) or `cover`.
+
+`cameraDevices()` lists cameras as `{deviceId, label}`, the same entries as the React Native SDK's `useCamera().cameraDevices`.
+
+`selectCamera(deviceId, {current})` selects that camera and returns the video stream to show. [current] is the preview already showing. The same `deviceId` returns [current]. When [current] already has a video track, that track is switched in place and [current] is returned. Opening a second camera and stopping the first makes `replaceTrack` fail on Android and iOS. With no video track, `selectCamera` opens [deviceId]. An empty `deviceId` throws `ArgumentError`. This is the React Native SDK's `selectCamera(deviceId)`.
+
+On Android, `mirror` is set on the texture renderer and takes effect on the next drawn frame. `selectCamera` pauses that drawing, switches the camera, then resumes after `RTCView` applies its current `mirror`. The frame already on screen is not flipped. Calls are `setMirror` `{textureId, mirror}` and `setPaused` `{textureId, paused}` on `io.fishjam.client/video_mirror`.
+
+On iOS, `mirror` is a view transform. It updates when the widget rebuilds.
+
 ## 21. Logging
 
 One SDK logger, created from `FishjamClient(debug: bool)`. Messages are prefixed with `[FISHJAM]` and emitted

android/src/main/kotlin/io/fishjam/client/FishjamClientPlugin.kt

@@ -20,6 +20,7 @@ class FishjamClientPlugin : FlutterPlugin, ActivityAware {
     private lateinit var audioOutput: AudioOutputManager
     private var audioEventSink: EventChannel.EventSink? = null
     private lateinit var backgroundChannel: MethodChannel
+    private lateinit var videoChannel: MethodChannel
     private val notificationPermission = NotificationPermission()
     private var activityBinding: ActivityPluginBinding? = null
     private lateinit var pipChannel: MethodChannel
@@ -62,6 +63,8 @@ class FishjamClientPlugin : FlutterPlugin, ActivityAware {
                 pipEventSink = null
             }
         })
+        videoChannel = MethodChannel(binding.binaryMessenger, VIDEO_CHANNEL)
+        videoChannel.setMethodCallHandler(::onVideoMethodCall)
     }
 
     private fun onAudioMethodCall(call: MethodCall, result: Result) {
@@ -98,6 +101,44 @@ class FishjamClientPlugin : FlutterPlugin, ActivityAware {
         }
     }
 
+    private fun onVideoMethodCall(call: MethodCall, result: Result) {
+        when (call.method) {
+            "setMirror" -> {
+                val args = call.arguments as? Map<*, *>
+                val textureId = (args?.get("textureId") as? Number)?.toLong()
+                val mirror = args?.get("mirror") as? Boolean
+                if (textureId == null || mirror == null) {
+                    result.error("invalid", "textureId and mirror are required", null)
+                    return
+                }
+                try {
+                    VideoMirror.setMirror(textureId, mirror)
+                    result.success(null)
+                } catch (e: Exception) {
+                    Log.w(TAG, "Could not set video mirror", e)
+                    result.error("mirror", e.message, null)
+                }
+            }
+            "setPaused" -> {
+                val args = call.arguments as? Map<*, *>
+                val textureId = (args?.get("textureId") as? Number)?.toLong()
+                val paused = args?.get("paused") as? Boolean
+                if (textureId == null || paused == null) {
+                    result.error("invalid", "textureId and paused are required", null)
+                    return
+                }
+                try {
+                    VideoMirror.setPaused(textureId, paused)
+                    result.success(null)
+                } catch (e: Exception) {
+                    Log.w(TAG, "Could not pause video", e)
+                    result.error("paused", e.message, null)
+                }
+            }
+            else -> result.notImplemented()
+        }
+    }
+
     override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) {
         audioChannel.setMethodCallHandler(null)
         audioEvents.setStreamHandler(null)
@@ -107,6 +148,7 @@ class FishjamClientPlugin : FlutterPlugin, ActivityAware {
         pipChannel.setMethodCallHandler(null)
         pipEvents.setStreamHandler(null)
         pipEventSink = null
+        videoChannel.setMethodCallHandler(null)
     }
 
     override fun onAttachedToActivity(binding: ActivityPluginBinding) {
@@ -160,5 +202,6 @@ class FishjamClientPlugin : FlutterPlugin, ActivityAware {
         private const val BACKGROUND_CHANNEL = "io.fishjam.client/background"
         private const val PIP_CHANNEL = "io.fishjam.client/pip"
         private const val PIP_EVENTS_CHANNEL = "io.fishjam.client/pip_events"
+        private const val VIDEO_CHANNEL = "io.fishjam.client/video_mirror"
     }
 }

android/src/main/kotlin/io/fishjam/client/VideoMirror.kt

@@ -0,0 +1,50 @@
+package io.fishjam.client
+
+import android.util.LongSparseArray
+
+/**
+ * Mirror and pause for flutter_webrtc's texture renderer, looked up by
+ * reflection so this plugin does not depend on flutter_webrtc.
+ * `com.cloudwebrtc.webrtc.**` is kept by that package, so these names
+ * survive shrinking.
+ *
+ * [setPaused] `true` calls `pauseVideo` (the last frame stays). `false`
+ * calls `disableFpsReduction`. The mirror is set while drawing is paused.
+ */
+internal object VideoMirror {
+    fun setMirror(textureId: Long, mirror: Boolean) {
+        invoke(textureId, "setMirror", mirror)
+    }
+
+    fun setPaused(textureId: Long, paused: Boolean) {
+        invoke(textureId, if (paused) "pauseVideo" else "disableFpsReduction")
+    }
+
+    private fun invoke(textureId: Long, methodName: String, argument: Boolean? = null) {
+        val renderer = renderer(textureId)
+        val method = renderer.javaClass.methods.firstOrNull { method ->
+            method.name == methodName &&
+                method.parameterTypes.size == if (argument == null) 0 else 1
+        } ?: error("video renderer has no $methodName")
+        if (argument == null) method.invoke(renderer) else method.invoke(renderer, argument)
+    }
+
+    private fun renderer(textureId: Long): Any {
+        val pluginClass = Class.forName("com.cloudwebrtc.webrtc.FlutterWebRTCPlugin")
+        val plugin = pluginClass.getField("sharedSingleton").get(null)
+            ?: error("FlutterWebRTCPlugin.sharedSingleton is null")
+        val handler = readField(plugin, "methodCallHandler")
+            ?: error("flutter_webrtc has no method handler")
+        val renders = readField(handler, "renders") as LongSparseArray<*>
+        val render = renders.get(textureId)
+            ?: error("no video renderer for texture $textureId")
+        return readField(render, "surfaceTextureRenderer")
+            ?: error("video renderer has no surface")
+    }
+
+    private fun readField(target: Any, name: String): Any? {
+        val field = target.javaClass.getDeclaredField(name)
+        field.isAccessible = true
+        return field.get(target)
+    }
+}

example/integration_test/room_test.dart

@@ -5,7 +5,6 @@ import 'dart:typed_data';
 
 import 'package:fishjam_client/fishjam_client.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:flutter_webrtc/flutter_webrtc.dart';
 import 'package:http/http.dart' as http;
 import 'package:integration_test/integration_test.dart';
 

example/lib/room_screen.dart

@@ -3,12 +3,11 @@ import 'dart:io';
 
 import 'package:fishjam_client/fishjam_client.dart';
 import 'package:flutter/material.dart';
-import 'package:flutter_webrtc/flutter_webrtc.dart';
 
 import 'sandbox.dart';
 
 /// A minimal room: publishes camera and microphone, renders remote video,
-/// mute toggles and leave.
+/// mute toggles, camera switch, picture-in-picture and leave.
 class RoomScreen extends StatefulWidget {
   const RoomScreen({
     super.key,
@@ -53,12 +52,14 @@ class _RoomScreenState extends State<RoomScreen> {
   final _subscriptions = <StreamSubscription<Object?>>[];
 
   MediaStream? _localStream;
+  MediaStream? _cameraStream;
   MediaStreamTrack? _camera;
   MediaStreamTrack? _microphone;
   String? _cameraTrackId;
   String? _microphoneTrackId;
   bool _cameraOn = true;
   bool _microphoneOn = true;
+  bool _frontCamera = true;
   String _status = 'Connecting…';
   final _audioOutput = AudioOutputManager.instance;
   final _callKit = CallKit.instance;
@@ -195,6 +196,7 @@ class _RoomScreenState extends State<RoomScreen> {
         'video': {'facingMode': 'user'},
       });
       _localStream = stream;
+      _cameraStream = stream;
       _camera = stream.getVideoTracks().firstOrNull;
       _microphone = stream.getAudioTracks().firstOrNull;
       if (mounted) setState(() {});
@@ -325,6 +327,35 @@ class _RoomScreenState extends State<RoomScreen> {
     );
   }
 
+  Future<void> _switchCamera() async {
+    final camera = _camera;
+    if (camera == null) return;
+    try {
+      final cameras = await cameraDevices();
+      final currentId = camera.getSettings()['deviceId'];
+      final next = cameras
+          .where((device) => device.deviceId != currentId)
+          .firstOrNull;
+      if (next == null) return;
+      final stream = await selectCamera(next.deviceId, current: _cameraStream);
+      final track = stream.getVideoTracks().firstOrNull;
+      if (track != null && _cameraTrackId != null && track.id != camera.id) {
+        await _client.replaceTrack(_cameraTrackId!, track);
+      }
+      final label = next.label.toLowerCase();
+      final front = label.contains('front');
+      final back = label.contains('back');
+      if (!mounted) return;
+      setState(() {
+        _cameraStream = stream;
+        _camera = track;
+        if (front || back) _frontCamera = front;
+      });
+    } on Object catch (e) {
+      _setStatus('Error: $e');
+    }
+  }
+
   Future<void> _toggleMicrophone() async {
     final on = !_microphoneOn;
     setState(() => _microphoneOn = on);
@@ -385,27 +416,40 @@ class _RoomScreenState extends State<RoomScreen> {
       }
       unawaited(stream.dispose());
     }
+    final cameraStream = _cameraStream;
+    if (cameraStream != null && cameraStream != stream) {
+      for (final track in cameraStream.getTracks()) {
+        unawaited(track.stop());
+      }
+      unawaited(cameraStream.dispose());
+    }
     super.dispose();
   }
 
   @override
   Widget build(BuildContext context) {
     final tiles = [
       _VideoTile(
-        stream: _localStream,
         label: '${widget.displayName} (you)',
-        mirror: true,
-        pip: _localPip,
-        pipOptions: _noPip,
+        child: RTCView(
+          mediaStream: _cameraStream,
+          mirror: _frontCamera,
+          objectFit: RTCViewObjectFit.cover,
+        ),
       ),
-      for (final video in _remote.values)
+      for (final entry in _remote.entries)
         _VideoTile(
-          stream: video.stream,
-          label: video.label,
-          pip: identical(video, _remote.values.first) ? _remotePip : null,
-          pipOptions: identical(video, _remote.values.first)
-              ? _pipOptions
-              : _noPip,
+          key: ValueKey(entry.key),
+          label: entry.value.label,
+          child: PictureInPictureView(
+            mediaStream: entry.value.stream,
+            controller: identical(entry.value, _remote.values.first)
+                ? _remotePip
+                : null,
+            pipOptions: identical(entry.value, _remote.values.first)
+                ? _pipOptions
+                : _noPip,
+          ),
         ),
     ];
     return Scaffold(
@@ -443,6 +487,11 @@ class _RoomScreenState extends State<RoomScreen> {
           onPressed: _toggleCamera,
           icon: Icon(_cameraOn ? Icons.videocam : Icons.videocam_off),
         ),
+        IconButton.filledTonal(
+          tooltip: 'Switch camera',
+          onPressed: _camera == null ? null : _switchCamera,
+          icon: const Icon(Icons.cameraswitch),
+        ),
         IconButton.filledTonal(
           tooltip: 'Picture in picture',
           onPressed:
@@ -468,35 +517,18 @@ class _RoomScreenState extends State<RoomScreen> {
 }
 
 class _VideoTile extends StatelessWidget {
-  const _VideoTile({
-    required this.label,
-    required this.pipOptions,
-    this.stream,
-    this.pip,
-    this.mirror = false,
-  });
+  const _VideoTile({super.key, required this.child, required this.label});
 
-  final MediaStream? stream;
+  final Widget child;
   final String label;
-  final PictureInPictureController? pip;
-  final PictureInPictureOptions pipOptions;
-  final bool mirror;
 
   @override
   Widget build(BuildContext context) => ClipRRect(
     borderRadius: BorderRadius.circular(8),
     child: Stack(
       fit: StackFit.expand,
       children: [
-        ColoredBox(
-          color: Colors.black,
-          child: PictureInPictureView(
-            mediaStream: stream,
-            controller: pip,
-            mirror: mirror,
-            pipOptions: pipOptions,
-          ),
-        ),
+        ColoredBox(color: Colors.black, child: child),
         Positioned(
           left: 8,
           bottom: 8,

lib/fishjam_client.dart

@@ -1,6 +1,9 @@
 /// Fishjam client SDK for Flutter. Start with `FishjamClient`.
 library;
 
+export 'package:flutter_webrtc/flutter_webrtc.dart'
+    show MediaStream, MediaStreamTrack, navigator;
+
 export 'src/audio_output/audio_output_manager.dart'
     show
         AndroidAudioOutput,
@@ -61,3 +64,5 @@ export 'src/rtc/rtc_adapter.dart' show MediaKind, PeerConnectionState, RtcStats;
 export 'src/signaling/auth.dart' show fishjamUrlFromId;
 export 'src/tracks/bandwidth.dart' show simulcastCapsKbps, singleStreamCapKbps;
 export 'src/version.dart' show packageVersion;
+export 'src/video/rtc_view.dart'
+    show CameraDevice, RTCView, RTCViewObjectFit, cameraDevices, selectCamera;