[camera_windows] Revert: Support image streams on Windows platform (flutter#7951)

This reverts commit b31a279 (flutter#7067)

The implementation had significant bugs:
- It had asynchronous results, but never responded to them, violating the engine API contract and preventing futures from completing.
- It `std::move`d pointers between classes, while still keeping them as ivars and global references and referring to them from long-lived handlers.

Author: stuartmorgan-g

packages/camera/camera_windows/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 0.2.6
+
+* Reverts streaming frame support, as the implementation was incorrect and never
+  exposed.
+
 ## 0.2.5+1
 
 * Updates C++ to Dart communication to use Pigeon.

packages/camera/camera_windows/lib/camera_windows.dart

@@ -11,7 +11,6 @@ import 'package:flutter/widgets.dart';
 import 'package:stream_transform/stream_transform.dart';
 
 import 'src/messages.g.dart';
-import 'type_conversion.dart';
 
 /// An implementation of [CameraPlatform] for Windows.
 class CameraWindows extends CameraPlatform {
@@ -33,12 +32,6 @@ class CameraWindows extends CameraPlatform {
   final Map<int, HostCameraMessageHandler> hostCameraHandlers =
       <int, HostCameraMessageHandler>{};
 
-  // The stream to receive frames from the native code.
-  StreamSubscription<dynamic>? _platformImageStreamSubscription;
-
-  // The stream for vending frames to platform interface clients.
-  StreamController<CameraImageData>? _frameStreamController;
-
   /// The controller that broadcasts events coming from handleCameraMethodCall
   ///
   /// It is a `broadcast` because multiple controllers will connect to
@@ -241,57 +234,6 @@ class CameraWindows extends CameraPlatform {
         'resumeVideoRecording() is not supported due to Win32 API limitations.');
   }
 
-  @override
-  Stream<CameraImageData> onStreamedFrameAvailable(int cameraId,
-      {CameraImageStreamOptions? options}) {
-    _installStreamController(
-        onListen: () => _onFrameStreamListen(cameraId),
-        onCancel: () => _onFrameStreamCancel(cameraId));
-    return _frameStreamController!.stream;
-  }
-
-  StreamController<CameraImageData> _installStreamController(
-      {void Function()? onListen, void Function()? onCancel}) {
-    _frameStreamController = StreamController<CameraImageData>(
-      onListen: onListen ?? () {},
-      onPause: _onFrameStreamPauseResume,
-      onResume: _onFrameStreamPauseResume,
-      onCancel: onCancel ?? () {},
-    );
-    return _frameStreamController!;
-  }
-
-  void _onFrameStreamListen(int cameraId) {
-    _startPlatformStream(cameraId);
-  }
-
-  Future<void> _startPlatformStream(int cameraId) async {
-    _startStreamListener();
-    await _hostApi.startImageStream(cameraId);
-  }
-
-  void _startStreamListener() {
-    const EventChannel cameraEventChannel =
-        EventChannel('plugins.flutter.io/camera_android/imageStream');
-    _platformImageStreamSubscription =
-        cameraEventChannel.receiveBroadcastStream().listen((dynamic imageData) {
-      _frameStreamController!
-          .add(cameraImageFromPlatformData(imageData as Map<dynamic, dynamic>));
-    });
-  }
-
-  FutureOr<void> _onFrameStreamCancel(int cameraId) async {
-    await _hostApi.stopImageStream(cameraId);
-    await _platformImageStreamSubscription?.cancel();
-    _platformImageStreamSubscription = null;
-    _frameStreamController = null;
-  }
-
-  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

@@ -362,56 +362,6 @@ class CameraApi {
     }
   }
 
-  /// Starts the image stream for the given camera.
-  Future<void> startImageStream(int cameraId) async {
-    final String pigeonVar_channelName =
-        'dev.flutter.pigeon.camera_windows.CameraApi.startImageStream$pigeonVar_messageChannelSuffix';
-    final BasicMessageChannel<Object?> pigeonVar_channel =
-        BasicMessageChannel<Object?>(
-      pigeonVar_channelName,
-      pigeonChannelCodec,
-      binaryMessenger: pigeonVar_binaryMessenger,
-    );
-    final List<Object?>? pigeonVar_replyList =
-        await pigeonVar_channel.send(<Object?>[cameraId]) as List<Object?>?;
-    if (pigeonVar_replyList == null) {
-      throw _createConnectionError(pigeonVar_channelName);
-    } else if (pigeonVar_replyList.length > 1) {
-      throw PlatformException(
-        code: pigeonVar_replyList[0]! as String,
-        message: pigeonVar_replyList[1] as String?,
-        details: pigeonVar_replyList[2],
-      );
-    } else {
-      return;
-    }
-  }
-
-  /// Stops the image stream for the given camera.
-  Future<void> stopImageStream(int cameraId) async {
-    final String pigeonVar_channelName =
-        'dev.flutter.pigeon.camera_windows.CameraApi.stopImageStream$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 {
-      return;
-    }
-  }
-
   /// Starts the preview stream for the given camera.
   Future<void> pausePreview(int cameraId) async {
     final String pigeonVar_channelName =

packages/camera/camera_windows/lib/type_conversion.dart

@@ -70,14 +70,6 @@ abstract class CameraApi {
   @async
   String stopVideoRecording(int cameraId);
 
-  /// Starts the image stream for the given camera.
-  @async
-  void startImageStream(int cameraId);
-
-  /// Stops the image stream for the given camera.
-  @async
-  void stopImageStream(int cameraId);
-
   /// Starts the preview stream for the given camera.
   @async
   void pausePreview(int cameraId);

packages/camera/camera_windows/pigeons/messages.dart

@@ -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: 0.2.5+1
+version: 0.2.6
 
 environment:
   sdk: ^3.3.0

packages/camera/camera_windows/pubspec.yaml

@@ -22,8 +22,6 @@ enum class PendingResultType {
   kTakePicture,
   kStartRecord,
   kStopRecord,
-  kStartStream,
-  kStopStream,
   kPausePreview,
   kResumePreview,
 };

packages/camera/camera_windows/windows/camera.h

@@ -4,8 +4,6 @@
 
 #include "camera_plugin.h"
 
-#include <flutter/event_channel.h>
-#include <flutter/event_stream_handler_functions.h>
 #include <flutter/flutter_view.h>
 #include <flutter/method_channel.h>
 #include <flutter/plugin_registrar_windows.h>
@@ -34,10 +32,6 @@ namespace {
 
 const std::string kPictureCaptureExtension = "jpeg";
 const std::string kVideoCaptureExtension = "mp4";
-constexpr char kFrameEventChannelName[] =
-    "plugins.flutter.io/camera_android/imageStream";
-
-std::unique_ptr<flutter::EventSink<flutter::EncodableValue>> event_sink;
 
 // Builds CaptureDeviceInfo object from given device holding device name and id.
 std::unique_ptr<CaptureDeviceInfo> GetDeviceInfo(IMFActivate* device) {
@@ -122,34 +116,12 @@ std::optional<std::string> GetFilePathForVideo() {
 }
 }  // namespace
 
-// a setter for the event sink helpful for testing.
-void CameraPlugin::SetEventSink(
-    std::unique_ptr<flutter::EventSink<flutter::EncodableValue>> events) {
-  event_sink = std::move(events);
-}
-
 // static
 void CameraPlugin::RegisterWithRegistrar(
     flutter::PluginRegistrarWindows* registrar) {
   std::unique_ptr<CameraPlugin> plugin = std::make_unique<CameraPlugin>(
       registrar->texture_registrar(), registrar->messenger());
 
-  auto frameEventchannel = std::make_unique<flutter::EventChannel<>>(
-      registrar->messenger(), kFrameEventChannelName,
-      &flutter::StandardMethodCodec::GetInstance());
-
-  auto event_channel_handler =
-      std::make_unique<flutter::StreamHandlerFunctions<>>(
-          [plugin = plugin.get()](auto arguments, auto events) {
-            plugin->SetEventSink(std::move(events));
-            return nullptr;
-          },
-          [](auto arguments) {
-            event_sink.reset();
-            return nullptr;
-          });
-  frameEventchannel->SetStreamHandler(std::move(event_channel_handler));
-
   CameraApi::SetUp(registrar->messenger(), plugin.get());
 
   registrar->AddPlugin(std::move(plugin));
@@ -369,53 +341,6 @@ void CameraPlugin::StopVideoRecording(
   }
 }
 
-void CameraPlugin::StartImageStream(
-    int64_t camera_id,
-    std::function<void(std::optional<FlutterError> reply)> result) {
-  // check if request already exists
-  Camera* camera = GetCameraByCameraId(camera_id);
-  if (!camera) {
-    return result(FlutterError("camera_error", "Camera not created"));
-  }
-  if (camera->HasPendingResultByType(PendingResultType::kStartStream)) {
-    return result(
-        FlutterError("camera_error", "Pending start stream request exists"));
-  }
-
-  if (!event_sink) {
-    return result(FlutterError("camera_error",
-                               "Unable to make event channel from windows"));
-  }
-
-  if (camera->AddPendingVoidResult(PendingResultType::kStartStream,
-                                   std::move(result))) {
-    CaptureController* cc = camera->GetCaptureController();
-    assert(cc);
-    cc->StartImageStream(std::move(event_sink));
-  }
-}
-
-void CameraPlugin::StopImageStream(
-    int64_t camera_id,
-    std::function<void(std::optional<FlutterError> reply)> result) {
-  // check if request already exists
-  Camera* camera = GetCameraByCameraId(camera_id);
-  if (!camera) {
-    return result(FlutterError("camera_error", "Camera not created"));
-  }
-  if (camera->HasPendingResultByType(PendingResultType::kStopStream)) {
-    return result(
-        FlutterError("camera_error", "Pending stop stream request exists"));
-  }
-
-  if (camera->AddPendingVoidResult(PendingResultType::kStopStream,
-                                   std::move(result))) {
-    CaptureController* cc = camera->GetCaptureController();
-    assert(cc);
-    cc->StopImageStream();
-  }
-}
-
 void CameraPlugin::TakePicture(
     int64_t camera_id, std::function<void(ErrorOr<std::string> reply)> result) {
   auto camera = GetCameraByCameraId(camera_id);

packages/camera/camera_windows/windows/camera_plugin.cpp

@@ -31,8 +31,6 @@ class CameraPlugin : public flutter::Plugin,
                      public CameraApi,
                      public VideoCaptureDeviceEnumerator {
  public:
-  void SetEventSink(
-      std::unique_ptr<flutter::EventSink<flutter::EncodableValue>> events);
   static void RegisterWithRegistrar(flutter::PluginRegistrarWindows* registrar);
 
   CameraPlugin(flutter::TextureRegistrar* texture_registrar,
@@ -70,12 +68,6 @@ class CameraPlugin : public flutter::Plugin,
   void StopVideoRecording(
       int64_t camera_id,
       std::function<void(ErrorOr<std::string> reply)> result) override;
-  void StartImageStream(
-      int64_t camera_id,
-      std::function<void(std::optional<FlutterError> reply)> result) override;
-  void StopImageStream(
-      int64_t camera_id,
-      std::function<void(std::optional<FlutterError> reply)> result) override;
   void TakePicture(
       int64_t camera_id,
       std::function<void(ErrorOr<std::string> reply)> result) override;

packages/camera/camera_windows/windows/camera_plugin.h

@@ -5,14 +5,11 @@
 #include "capture_controller.h"
 
 #include <comdef.h>
-#include <flutter/event_stream_handler_functions.h>
-#include <flutter/standard_method_codec.h>
 #include <wincodec.h>
 #include <wrl/client.h>
 
 #include <cassert>
 #include <chrono>
-#include <iostream>
 
 #include "com_heap_ptr.h"
 #include "photo_handler.h"
@@ -553,16 +550,6 @@ void CaptureControllerImpl::StopRecord() {
                            "Failed to stop video recording");
   }
 }
-void CaptureControllerImpl::StartImageStream(
-    std::unique_ptr<flutter::EventSink<flutter::EncodableValue>> sink) {
-  assert(capture_controller_listener_);
-  image_stream_sink_ = std::move(sink);
-}
-
-void CaptureControllerImpl::StopImageStream() {
-  assert(capture_controller_listener_);
-  image_stream_sink_.reset();
-}
 
 // Starts capturing preview frames using preview handler
 // After first frame is captured, OnPreviewStarted is called
@@ -856,32 +843,6 @@ bool CaptureControllerImpl::UpdateBuffer(uint8_t* buffer,
   if (!texture_handler_) {
     return false;
   }
-  if (image_stream_sink_) {
-    // Convert the buffer data to a std::vector<uint8_t>.
-    std::vector<uint8_t> buffer_data(buffer, buffer + data_length);
-
-    // Ensure preview_frame_height_ and preview_frame_width_ are of supported
-    // types.
-    int preview_frame_height = static_cast<int>(preview_frame_height_);
-    int preview_frame_width = static_cast<int>(preview_frame_width_);
-
-    // Create a map to hold the buffer data and data length.
-    flutter::EncodableMap data_map;
-    data_map[flutter::EncodableValue("data")] =
-        flutter::EncodableValue(buffer_data);
-    data_map[flutter::EncodableValue("height")] =
-        flutter::EncodableValue(preview_frame_height);
-    data_map[flutter::EncodableValue("width")] =
-        flutter::EncodableValue(preview_frame_width);
-    data_map[flutter::EncodableValue("length")] =
-        flutter::EncodableValue(static_cast<int>(data_length));
-
-    // Wrap the map in a flutter::EncodableValue.
-    flutter::EncodableValue encoded_value(data_map);
-
-    // Send the encoded value through the image_stream_sink_.
-    image_stream_sink_->Success(encoded_value);
-  }
   return texture_handler_->UpdateBuffer(buffer, data_length);
 }