[camera_windows] Restore image streaming support

packages/camera/camera_windows/CHANGELOG.md

@@ -1,5 +1,6 @@
-## 0.2.6+2
+## 0.2.7
 
+* Restores support for streaming frames.
 * Fixes compile errors under strict standards mode.
 * Updates minimum supported SDK version to Flutter 3.22/Dart 3.4.
 

packages/camera/camera_windows/lib/camera_windows.dart

@@ -11,6 +11,7 @@ import 'package:flutter/widgets.dart';
 import 'package:stream_transform/stream_transform.dart';
 
 import 'src/messages.g.dart';
+import 'src/type_conversion.dart';
 
 /// An implementation of [CameraPlatform] for Windows.
 class CameraWindows extends CameraPlatform {
@@ -234,6 +235,40 @@ class CameraWindows extends CameraPlatform {
         'resumeVideoRecording() is not supported due to Win32 API limitations.');
   }
 
+  @override
+  bool supportsImageStreaming() => true;
+
+  @override
+  Stream<CameraImageData> onStreamedFrameAvailable(int cameraId,
+      {CameraImageStreamOptions? options}) {
+    late StreamController<CameraImageData> controller;
+    StreamSubscription<dynamic>? subscription;
+
+    controller = StreamController<CameraImageData>(
+        onListen: () async {
+          final String eventChannelName =
+              await _hostApi.startImageStream(cameraId);
+          final EventChannel imageStreamChannel =
+              EventChannel(eventChannelName);
+          subscription = imageStreamChannel.receiveBroadcastStream().listen(
+              (dynamic image) => controller.add(
+                  cameraImageFromPlatformData(image as Map<dynamic, dynamic>)));
+        },
+        onPause: _onFrameStreamPauseResume,
+        onResume: _onFrameStreamPauseResume,
+        onCancel: () async {
+          // Cancelling the subscription stops the image capture on the native side.
+          await subscription?.cancel();
+        });
+
+    return controller.stream;
+  }
+
+  void _onFrameStreamPauseResume() {
+    throw CameraException('InvalidCall',
+        'Pause and resume are not supported for onStreamedFrameAvailable');
+  }
+
   @override
   Future<void> setFlashMode(int cameraId, FlashMode mode) async {
     // TODO(jokerttu): Implement flash mode support, https://github.com/flutter/flutter/issues/97537.

packages/camera/camera_windows/lib/src/messages.g.dart

@@ -1,7 +1,7 @@
 // Copyright 2013 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
-// Autogenerated from Pigeon (v22.6.0), do not edit directly.
+// Autogenerated from Pigeon (v22.7.4), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 // ignore_for_file: public_member_api_docs, non_constant_identifier_names, avoid_as, unused_import, unnecessary_parenthesis, prefer_null_aware_operators, omit_local_variable_types, unused_shown_name, unnecessary_import, no_leading_underscores_for_local_identifiers
 
@@ -108,6 +108,43 @@ class PlatformSize {
   }
 }
 
+/// A representation of frame data from the camera preview stream.
+class PlatformFrameData {
+  PlatformFrameData({
+    required this.data,
+    required this.width,
+    required this.height,
+    required this.length,
+  });
+
+  List<int> data;
+
+  int width;
+
+  int height;
+
+  int length;
+
+  Object encode() {
+    return <Object?>[
+      data,
+      width,
+      height,
+      length,
+    ];
+  }
+
+  static PlatformFrameData decode(Object result) {
+    result as List<Object?>;
+    return PlatformFrameData(
+      data: (result[0] as List<Object?>?)!.cast<int>(),
+      width: result[1]! as int,
+      height: result[2]! as int,
+      length: result[3]! as int,
+    );
+  }
+}
+
 class _PigeonCodec extends StandardMessageCodec {
   const _PigeonCodec();
   @override
@@ -124,6 +161,9 @@ class _PigeonCodec extends StandardMessageCodec {
     } else if (value is PlatformSize) {
       buffer.putUint8(131);
       writeValue(buffer, value.encode());
+    } else if (value is PlatformFrameData) {
+      buffer.putUint8(132);
+      writeValue(buffer, value.encode());
     } else {
       super.writeValue(buffer, value);
     }
@@ -139,6 +179,8 @@ class _PigeonCodec extends StandardMessageCodec {
         return PlatformMediaSettings.decode(readValue(buffer)!);
       case 131:
         return PlatformSize.decode(readValue(buffer)!);
+      case 132:
+        return PlatformFrameData.decode(readValue(buffer)!);
       default:
         return super.readValueOfType(type, buffer);
     }
@@ -362,6 +404,38 @@ class CameraApi {
     }
   }
 
+  /// Starts the image stream for the given camera.
+  /// Returns the name of the [EventChannel] used to deliver the images.
+  /// Cancelling the subscription to the channel stops the capture.
+  Future<String> startImageStream(int cameraId) async {
+    final String pigeonVar_channelName =
+        'dev.flutter.pigeon.camera_windows.CameraApi.startImageStream$pigeonVar_messageChannelSuffix';
+    final BasicMessageChannel<Object?> pigeonVar_channel =
+        BasicMessageChannel<Object?>(
+      pigeonVar_channelName,
+      pigeonChannelCodec,
+      binaryMessenger: pigeonVar_binaryMessenger,
+    );
+    final List<Object?>? pigeonVar_replyList =
+        await pigeonVar_channel.send(<Object?>[cameraId]) as List<Object?>?;
+    if (pigeonVar_replyList == null) {
+      throw _createConnectionError(pigeonVar_channelName);
+    } else if (pigeonVar_replyList.length > 1) {
+      throw PlatformException(
+        code: pigeonVar_replyList[0]! as String,
+        message: pigeonVar_replyList[1] as String?,
+        details: pigeonVar_replyList[2],
+      );
+    } else if (pigeonVar_replyList[0] == null) {
+      throw PlatformException(
+        code: 'null-error',
+        message: 'Host platform returned null value for non-null return value.',
+      );
+    } else {
+      return (pigeonVar_replyList[0] as String?)!;
+    }
+  }
+
   /// Starts the preview stream for the given camera.
   Future<void> pausePreview(int cameraId) async {
     final String pigeonVar_channelName =

packages/camera/camera_windows/lib/src/type_conversion.dart

@@ -0,0 +1,25 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:typed_data';
+
+import 'package:camera_platform_interface/camera_platform_interface.dart';
+
+/// Converts method channel call [data] for `receivedImageStreamData` to a
+/// [CameraImageData].
+CameraImageData cameraImageFromPlatformData(Map<dynamic, dynamic> data) {
+  return CameraImageData(
+      format: const CameraImageFormat(ImageFormatGroup.bgra8888, raw: 0),
+      height: data['height'] as int,
+      width: data['width'] as int,
+      lensAperture: data['lensAperture'] as double?,
+      sensorExposureTime: data['sensorExposureTime'] as int?,
+      sensorSensitivity: data['sensorSensitivity'] as double?,
+      planes: <CameraImagePlane>[
+        CameraImagePlane(
+          bytes: data['data'] as Uint8List,
+          bytesPerRow: (data['width'] as int) * 4,
+        )
+      ]);
+}

packages/camera/camera_windows/pigeons/messages.dart

@@ -40,6 +40,21 @@ class PlatformSize {
   final double height;
 }
 
+/// A representation of frame data from the camera preview stream.
+class PlatformFrameData {
+  PlatformFrameData({
+    required this.data,
+    required this.width,
+    required this.height,
+    required this.length,
+  });
+
+  final List<int> data;
+  final int width;
+  final int height;
+  final int length;
+}
+
 @HostApi()
 abstract class CameraApi {
   /// Returns the names of all of the available capture devices.
@@ -70,6 +85,11 @@ abstract class CameraApi {
   @async
   String stopVideoRecording(int cameraId);
 
+  /// Starts the image stream for the given camera.
+  /// Returns the name of the [EventChannel] used to deliver the images.
+  /// Cancelling the subscription to the channel stops the capture.
+  String startImageStream(int cameraId);
+
   /// Starts the preview stream for the given camera.
   @async
   void pausePreview(int cameraId);

packages/camera/camera_windows/pubspec.yaml

@@ -2,7 +2,7 @@ name: camera_windows
 description: A Flutter plugin for getting information about and controlling the camera on Windows.
 repository: https://github.com/flutter/packages/tree/main/packages/camera/camera_windows
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+camera%22
-version: 0.2.6+2
+version: 0.2.7
 
 environment:
   sdk: ^3.4.0
@@ -17,7 +17,7 @@ flutter:
         dartPluginClass: CameraWindows
 
 dependencies:
-  camera_platform_interface: ^2.6.0
+  camera_platform_interface: ^2.9.0
   cross_file: ^0.3.1
   flutter:
     sdk: flutter

packages/camera/camera_windows/test/camera_windows_test.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:async';
+
 import 'package:async/async.dart';
 import 'package:camera_platform_interface/camera_platform_interface.dart';
 import 'package:camera_windows/camera_windows.dart';
@@ -181,6 +183,11 @@ void main() {
             verify(mockApi.dispose(captureAny));
         expect(verification.captured[0], cameraId);
       });
+
+      test('Should report support for image streaming', () async {
+        final CameraWindows plugin = CameraWindows(api: MockCameraApi());
+        expect(plugin.supportsImageStreaming(), true);
+      });
     });
 
     group('Event Tests', () {
@@ -548,6 +555,15 @@ void main() {
             verify(mockApi.resumePreview(captureAny));
         expect(verification.captured[0], cameraId);
       });
+
+      test('Should start the image stream when it is subscribed', () async {
+        final Stream<CameraImageData> stream =
+            plugin.onStreamedFrameAvailable(cameraId);
+
+        await stream.listen((CameraImageData frame) {}).cancel();
+
+        verify(mockApi.startImageStream(cameraId));
+      });
     });
   });
 }

packages/camera/camera_windows/test/camera_windows_test.mocks.dart

@@ -166,24 +166,15 @@ class MockCameraApi extends _i1.Mock implements _i2.CameraApi {
       ) as _i4.Future<String>);
 
   @override
-  _i4.Future<void> startImageStream(int? cameraId) => (super.noSuchMethod(
+  _i4.Future<String> startImageStream(int? cameraId) => (super.noSuchMethod(
         Invocation.method(
           #startImageStream,
           [cameraId],
         ),
-        returnValue: _i4.Future<void>.value(),
-        returnValueForMissingStub: _i4.Future<void>.value(),
-      ) as _i4.Future<void>);
-
-  @override
-  _i4.Future<void> stopImageStream(int? cameraId) => (super.noSuchMethod(
-        Invocation.method(
-          #stopImageStream,
-          [cameraId],
-        ),
-        returnValue: _i4.Future<void>.value(),
-        returnValueForMissingStub: _i4.Future<void>.value(),
-      ) as _i4.Future<void>);
+        returnValue: _i4.Future<String>.value('imageStream/$cameraId'),
+        returnValueForMissingStub:
+            _i4.Future<String>.value('imageStream/$cameraId'),
+      ) as _i4.Future<String>);
 
   @override
   _i4.Future<void> pausePreview(int? cameraId) => (super.noSuchMethod(

packages/camera/camera_windows/windows/CMakeLists.txt

@@ -33,6 +33,9 @@ list(APPEND PLUGIN_SOURCES
   "texture_handler.h"
   "texture_handler.cpp"
   "com_heap_ptr.h"
+  "task_runner.h"
+  "task_runner_window.h"
+  "task_runner_window.cpp"
 )
 
 add_library(${PLUGIN_NAME} SHARED
@@ -84,6 +87,7 @@ add_executable(${TEST_RUNNER}
   test/camera_plugin_test.cpp
   test/camera_test.cpp
   test/capture_controller_test.cpp
+  test/task_runner_window_test.cpp
   ${PLUGIN_SOURCES}
 )
 apply_standard_settings(${TEST_RUNNER})

packages/camera/camera_windows/windows/camera.cpp

@@ -39,24 +39,26 @@ CameraImpl::~CameraImpl() {
 
 bool CameraImpl::InitCamera(flutter::TextureRegistrar* texture_registrar,
                             flutter::BinaryMessenger* messenger,
-                            const PlatformMediaSettings& media_settings) {
+                            const PlatformMediaSettings& media_settings,
+                            std::shared_ptr<TaskRunner> task_runner) {
   auto capture_controller_factory =
       std::make_unique<CaptureControllerFactoryImpl>();
   return InitCamera(std::move(capture_controller_factory), texture_registrar,
-                    messenger, media_settings);
+                    messenger, media_settings, task_runner);
 }
 
 bool CameraImpl::InitCamera(
     std::unique_ptr<CaptureControllerFactory> capture_controller_factory,
     flutter::TextureRegistrar* texture_registrar,
     flutter::BinaryMessenger* messenger,
-    const PlatformMediaSettings& media_settings) {
+    const PlatformMediaSettings& media_settings,
+    std::shared_ptr<TaskRunner> task_runner) {
   assert(!device_id_.empty());
   messenger_ = messenger;
   capture_controller_ =
       capture_controller_factory->CreateCaptureController(this);
   return capture_controller_->InitCaptureDevice(texture_registrar, device_id_,
-                                                media_settings);
+                                                media_settings, task_runner);
 }
 
 bool CameraImpl::AddPendingVoidResult(

packages/camera/camera_windows/windows/camera.h

@@ -85,7 +85,8 @@ class Camera : public CaptureControllerListener {
   // Returns false if initialization fails.
   virtual bool InitCamera(flutter::TextureRegistrar* texture_registrar,
                           flutter::BinaryMessenger* messenger,
-                          const PlatformMediaSettings& media_settings) = 0;
+                          const PlatformMediaSettings& media_settings,
+                          std::shared_ptr<TaskRunner> task_runner) = 0;
 };
 
 // Concrete implementation of the |Camera| interface.
@@ -151,7 +152,8 @@ class CameraImpl : public Camera {
   }
   bool InitCamera(flutter::TextureRegistrar* texture_registrar,
                   flutter::BinaryMessenger* messenger,
-                  const PlatformMediaSettings& media_settings) override;
+                  const PlatformMediaSettings& media_settings,
+                  std::shared_ptr<TaskRunner> task_runner) override;
 
   // Initializes the camera and its associated capture controller.
   //
@@ -163,7 +165,8 @@ class CameraImpl : public Camera {
       std::unique_ptr<CaptureControllerFactory> capture_controller_factory,
       flutter::TextureRegistrar* texture_registrar,
       flutter::BinaryMessenger* messenger,
-      const PlatformMediaSettings& media_settings);
+      const PlatformMediaSettings& media_settings,
+      std::shared_ptr<TaskRunner> task_runner);
 
  private:
   // A generic type for any pending asyncronous result.
@@ -230,6 +233,7 @@ class CameraImpl : public Camera {
   std::unique_ptr<CaptureController> capture_controller_;
   std::unique_ptr<CameraEventApi> event_api_;
   flutter::BinaryMessenger* messenger_ = nullptr;
+  std::shared_ptr<TaskRunner> task_runner_;
   int64_t camera_id_ = -1;
   std::string device_id_;
 };