Make {Start,Stop}ImageStream synchronous

The logic is synchronous, so there is no need to have the `@async`
annotation here.

Addresses:
  flutter#7067 (comment)

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 (v22.6.2), 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
 

packages/camera/camera_windows/pigeons/messages.dart

@@ -71,11 +71,9 @@ abstract class CameraApi {
   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.

packages/camera/camera_windows/windows/camera.h

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

packages/camera/camera_windows/windows/camera_plugin.cpp

@@ -369,51 +369,35 @@ void CameraPlugin::StopVideoRecording(
   }
 }
 
-void CameraPlugin::StartImageStream(
-    int64_t camera_id,
-    std::function<void(std::optional<FlutterError> reply)> result) {
-  // check if request already exists
+std::optional<FlutterError> CameraPlugin::StartImageStream(int64_t camera_id) {
   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"));
+    return FlutterError("camera_error", "Camera not created");
   }
 
   if (!event_sink) {
-    return result(FlutterError("camera_error",
-                               "Unable to make event channel from windows"));
+    return 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));
-  }
+  CaptureController* cc = camera->GetCaptureController();
+  assert(cc);
+  cc->StartImageStream(std::move(event_sink));
+
+  return std::nullopt;
 }
 
-void CameraPlugin::StopImageStream(
-    int64_t camera_id,
-    std::function<void(std::optional<FlutterError> reply)> result) {
-  // check if request already exists
+std::optional<FlutterError> CameraPlugin::StopImageStream(int64_t camera_id) {
   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"));
+    return FlutterError("camera_error", "Camera not created");
   }
 
-  if (camera->AddPendingVoidResult(PendingResultType::kStopStream,
-                                   std::move(result))) {
-    CaptureController* cc = camera->GetCaptureController();
-    assert(cc);
-    cc->StopImageStream();
-  }
+  CaptureController* cc = camera->GetCaptureController();
+  assert(cc);
+  cc->StopImageStream();
+
+  return std::nullopt;
 }
 
 void CameraPlugin::TakePicture(

packages/camera/camera_windows/windows/camera_plugin.h

@@ -70,12 +70,8 @@ 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;
+  std::optional<FlutterError> StartImageStream(int64_t camera_id) override;
+  std::optional<FlutterError> StopImageStream(int64_t camera_id) override;
   void TakePicture(
       int64_t camera_id,
       std::function<void(ErrorOr<std::string> reply)> result) override;

packages/camera/camera_windows/windows/messages.g.cpp

@@ -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 (v22.6.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 
 #undef _HAS_EXCEPTIONS
@@ -516,16 +516,15 @@ void CameraApi::SetUp(flutter::BinaryMessenger* binary_messenger,
                 return;
               }
               const int64_t camera_id_arg = encodable_camera_id_arg.LongValue();
-              api->StartImageStream(
-                  camera_id_arg, [reply](std::optional<FlutterError>&& output) {
-                    if (output.has_value()) {
-                      reply(WrapError(output.value()));
-                      return;
-                    }
-                    EncodableList wrapped;
-                    wrapped.push_back(EncodableValue());
-                    reply(EncodableValue(std::move(wrapped)));
-                  });
+              std::optional<FlutterError> output =
+                  api->StartImageStream(camera_id_arg);
+              if (output.has_value()) {
+                reply(WrapError(output.value()));
+                return;
+              }
+              EncodableList wrapped;
+              wrapped.push_back(EncodableValue());
+              reply(EncodableValue(std::move(wrapped)));
             } catch (const std::exception& exception) {
               reply(WrapError(exception.what()));
             }
@@ -552,16 +551,15 @@ void CameraApi::SetUp(flutter::BinaryMessenger* binary_messenger,
                 return;
               }
               const int64_t camera_id_arg = encodable_camera_id_arg.LongValue();
-              api->StopImageStream(
-                  camera_id_arg, [reply](std::optional<FlutterError>&& output) {
-                    if (output.has_value()) {
-                      reply(WrapError(output.value()));
-                      return;
-                    }
-                    EncodableList wrapped;
-                    wrapped.push_back(EncodableValue());
-                    reply(EncodableValue(std::move(wrapped)));
-                  });
+              std::optional<FlutterError> output =
+                  api->StopImageStream(camera_id_arg);
+              if (output.has_value()) {
+                reply(WrapError(output.value()));
+                return;
+              }
+              EncodableList wrapped;
+              wrapped.push_back(EncodableValue());
+              reply(EncodableValue(std::move(wrapped)));
             } catch (const std::exception& exception) {
               reply(WrapError(exception.what()));
             }

packages/camera/camera_windows/windows/messages.g.h

@@ -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 (v22.6.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 
 #ifndef PIGEON_MESSAGES_G_H_
@@ -190,13 +190,9 @@ class CameraApi {
       int64_t camera_id,
       std::function<void(ErrorOr<std::string> reply)> result) = 0;
   // Starts the image stream for the given camera.
-  virtual void StartImageStream(
-      int64_t camera_id,
-      std::function<void(std::optional<FlutterError> reply)> result) = 0;
+  virtual std::optional<FlutterError> StartImageStream(int64_t camera_id) = 0;
   // Stops the image stream for the given camera.
-  virtual void StopImageStream(
-      int64_t camera_id,
-      std::function<void(std::optional<FlutterError> reply)> result) = 0;
+  virtual std::optional<FlutterError> StopImageStream(int64_t camera_id) = 0;
   // Starts the preview stream for the given camera.
   virtual void PausePreview(
       int64_t camera_id,

packages/camera/camera_windows/windows/test/camera_plugin_test.cpp

@@ -29,6 +29,8 @@ using ::testing::EndsWith;
 using ::testing::Eq;
 using ::testing::Pointee;
 using ::testing::Return;
+using ::testing::Optional;
+using ::testing::Property;
 
 void MockInitCamera(MockCamera* camera, bool success) {
   EXPECT_CALL(*camera,
@@ -366,34 +368,14 @@ TEST(CameraPlugin, StartImageStreamHandlerCallsStartImageStream) {
         return cam->camera_id_ == camera_id;
       });
 
-  EXPECT_CALL(*camera,
-              HasPendingResultByType(Eq(PendingResultType::kStartStream)))
-      .Times(1)
-      .WillOnce(Return(false));
-
-  EXPECT_CALL(*camera,
-              AddPendingVoidResult(Eq(PendingResultType::kStartStream), _))
-      .Times(1)
-      .WillOnce([cam = camera.get()](
-                    PendingResultType type,
-                    std::function<void(std::optional<FlutterError>)> result) {
-        cam->pending_void_result_ = std::move(result);
-        return true;
-      });
-
   EXPECT_CALL(*camera, GetCaptureController)
       .Times(1)
       .WillOnce([cam = camera.get()]() {
-        assert(cam->pending_void_result_);
         return cam->capture_controller_.get();
       });
 
   EXPECT_CALL(*capture_controller, StartImageStream)
-      .Times(1)
-      .WillOnce([cam = camera.get()]() {
-        assert(cam->pending_void_result_);
-        return cam->pending_void_result_(std::nullopt);
-      });
+      .Times(1);
 
   camera->camera_id_ = mock_camera_id;
   camera->capture_controller_ = std::move(capture_controller);
@@ -402,24 +384,14 @@ TEST(CameraPlugin, StartImageStreamHandlerCallsStartImageStream) {
                           std::make_unique<MockBinaryMessenger>().get(),
                           std::make_unique<MockCameraFactory>());
 
-  // Add mocked camera to plugins camera list.
-  plugin.AddCamera(std::move(camera));
-
   // Set the event sink to a mocked event sink.
   auto mock_event_sink = std::make_unique<MockEventSink>();
   plugin.SetEventSink(std::move(mock_event_sink));
 
-  bool result_called = false;
-  std::function<void(std::optional<FlutterError>)> start_image_stream_result =
-      [&result_called](std::optional<FlutterError> reply) {
-        EXPECT_FALSE(result_called);  // Ensure only one reply call.
-        result_called = true;
-        EXPECT_FALSE(reply);
-      };
-
-  plugin.StartImageStream(mock_camera_id, std::move(start_image_stream_result));
+  // Add mocked camera to plugins camera list.
+  plugin.AddCamera(std::move(camera));
 
-  EXPECT_TRUE(result_called);
+  EXPECT_EQ(plugin.StartImageStream(mock_camera_id), std::nullopt);
 }
 
 TEST(CameraPlugin, StartImageStreamHandlerErrorOnInvalidCameraId) {
@@ -452,18 +424,7 @@ TEST(CameraPlugin, StartImageStreamHandlerErrorOnInvalidCameraId) {
   // Add mocked camera to plugins camera list.
   plugin.AddCamera(std::move(camera));
 
-  bool result_called = false;
-  std::function<void(std::optional<FlutterError>)> start_image_stream_result =
-      [&result_called](std::optional<FlutterError> reply) {
-        EXPECT_FALSE(result_called);  // Ensure only one reply call.
-        result_called = true;
-        EXPECT_TRUE(reply);
-      };
-
-  plugin.StartImageStream(missing_camera_id,
-                          std::move(start_image_stream_result));
-
-  EXPECT_TRUE(result_called);
+  EXPECT_THAT(plugin.StartImageStream(missing_camera_id), Optional(Property("code", &FlutterError::code, "camera_error")));
 }
 
 TEST(CameraPlugin, StopImageStreamHandlerCallsStopImageStream) {
@@ -481,34 +442,14 @@ TEST(CameraPlugin, StopImageStreamHandlerCallsStopImageStream) {
         return cam->camera_id_ == camera_id;
       });
 
-  EXPECT_CALL(*camera,
-              HasPendingResultByType(Eq(PendingResultType::kStopStream)))
-      .Times(1)
-      .WillOnce(Return(false));
-
-  EXPECT_CALL(*camera,
-              AddPendingVoidResult(Eq(PendingResultType::kStopStream), _))
-      .Times(1)
-      .WillOnce([cam = camera.get()](
-                    PendingResultType type,
-                    std::function<void(std::optional<FlutterError>)> result) {
-        cam->pending_void_result_ = std::move(result);
-        return true;
-      });
-
   EXPECT_CALL(*camera, GetCaptureController)
       .Times(1)
       .WillOnce([cam = camera.get()]() {
-        assert(cam->pending_void_result_);
         return cam->capture_controller_.get();
       });
 
   EXPECT_CALL(*capture_controller, StopImageStream)
-      .Times(1)
-      .WillOnce([cam = camera.get()]() {
-        assert(cam->pending_void_result_);
-        return cam->pending_void_result_(std::nullopt);
-      });
+      .Times(1);
 
   camera->camera_id_ = mock_camera_id;
   camera->capture_controller_ = std::move(capture_controller);
@@ -520,17 +461,7 @@ TEST(CameraPlugin, StopImageStreamHandlerCallsStopImageStream) {
   // Add mocked camera to plugins camera list.
   plugin.AddCamera(std::move(camera));
 
-  bool result_called = false;
-  std::function<void(std::optional<FlutterError>)> stop_image_stream_result =
-      [&result_called](std::optional<FlutterError> reply) {
-        EXPECT_FALSE(result_called);  // Ensure only one reply call.
-        result_called = true;
-        EXPECT_FALSE(reply);
-      };
-
-  plugin.StopImageStream(mock_camera_id, std::move(stop_image_stream_result));
-
-  EXPECT_TRUE(result_called);
+  EXPECT_EQ(plugin.StopImageStream(mock_camera_id), std::nullopt);
 }
 
 TEST(CameraPlugin, StopImageStreamHandlerErrorOnInvalidCameraId) {
@@ -563,18 +494,7 @@ TEST(CameraPlugin, StopImageStreamHandlerErrorOnInvalidCameraId) {
   // Add mocked camera to plugins camera list.
   plugin.AddCamera(std::move(camera));
 
-  bool result_called = false;
-  std::function<void(std::optional<FlutterError>)> stop_image_stream_result =
-      [&result_called](std::optional<FlutterError> reply) {
-        EXPECT_FALSE(result_called);  // Ensure only one reply call.
-        result_called = true;
-        EXPECT_TRUE(reply);
-      };
-
-  plugin.StopImageStream(missing_camera_id,
-                         std::move(stop_image_stream_result));
-
-  EXPECT_TRUE(result_called);
+  EXPECT_THAT(plugin.StopImageStream(missing_camera_id), Optional(Property("code", &FlutterError::code, "camera_error")));
 }
 
 TEST(CameraPlugin, InitializeHandlerErrorOnInvalidCameraId) {