camera: add TakePicture API implementation (#60)

One of implementation in #6

Signed-off-by: Hidenori Matsubayashi <hidenori.matsubayashi@gmail.com>

packages/camera/elinux/camera_elinux_plugin.cc

@@ -1,4 +1,4 @@
-// Copyright 2021 Sony Group Corporation. All rights reserved.
+// Copyright 2022 Sony Group Corporation. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -83,6 +83,9 @@ class CameraPlugin : public flutter::Plugin {
   void HandleInitializeCall(
       const flutter::EncodableValue* message,
       std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result);
+  void HandleTakePictureCall(
+      const flutter::EncodableValue* message,
+      std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result);
   void HandleStartImageStreamCall(
       const flutter::EncodableValue* message,
       std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result);
@@ -148,7 +151,7 @@ void CameraPlugin::HandleMethodCall(
   } else if (!method_name.compare(kCameraChannelApiInitialize)) {
     HandleInitializeCall(method_call.arguments(), std::move(result));
   } else if (!method_name.compare(kCameraChannelApiTakePicture)) {
-    result->NotImplemented();
+    HandleTakePictureCall(method_call.arguments(), std::move(result));
   } else if (!method_name.compare(kCameraChannelApiPrepareForVideoRecording)) {
     result->NotImplemented();
   } else if (!method_name.compare(kCameraChannelApiStartVideoRecording)) {
@@ -285,6 +288,26 @@ void CameraPlugin::HandleInitializeCall(
   result->Success();
 }
 
+void CameraPlugin::HandleTakePictureCall(
+    const flutter::EncodableValue* message,
+    std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result) {
+  if (!camera_) {
+    result->Error("Not found an active camera",
+                  "Check for creating a camera device");
+    return;
+  }
+  camera_->TakePicture([p_result = result.release()](
+                           const std::string& captured_file_path) {
+    if (!captured_file_path.empty()) {
+      flutter::EncodableValue value(captured_file_path);
+      p_result->Success(value);
+    } else {
+      p_result->Error("Failed to capture", "Failed to capture a camera image");
+    }
+    delete p_result;
+  });
+}
+
 void CameraPlugin::HandleStartImageStreamCall(
     const flutter::EncodableValue* message,
     std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result) {

packages/camera/elinux/gst_camera.cc

@@ -1,4 +1,4 @@
-// Copyright 2021 Sony Group Corporation. All rights reserved.
+// Copyright 2022 Sony Group Corporation. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -77,6 +77,19 @@ bool GstCamera::Stop() {
   return true;
 }
 
+void GstCamera::TakePicture(OnNotifyCaptured on_notify_captured) {
+  if (!gst_.camerabin) {
+    std::cerr << "Failed to take a picture" << std::endl;
+    return;
+  }
+
+  on_notify_captured_ = on_notify_captured;
+  std::string filename =
+      g_strdup_printf("captured_%04u.jpg", captured_count_++);
+  g_object_set(gst_.camerabin, "location", filename.c_str(), NULL);
+  g_signal_emit_by_name(gst_.camerabin, "start-capture", NULL);
+}
+
 bool GstCamera::SetZoomLevel(float zoom) {
   if (zoom_level_ == zoom) {
     return true;
@@ -280,6 +293,18 @@ void GstCamera::HandoffHandler(GstElement* fakesink, GstBuffer* buf,
 gboolean GstCamera::HandleGstMessage(GstBus* bus, GstMessage* message,
                                      gpointer user_data) {
   switch (GST_MESSAGE_TYPE(message)) {
+    case GST_MESSAGE_ELEMENT: {
+      auto const* st = gst_message_get_structure(message);
+      if (st) {
+        auto* self = reinterpret_cast<GstCamera*>(user_data);
+        if (gst_structure_has_name(st, "image-done") &&
+            self->on_notify_captured_) {
+          auto const* filename = gst_structure_get_string(st, "filename");
+          self->on_notify_captured_(filename);
+        }
+      }
+      break;
+    }
     case GST_MESSAGE_WARNING: {
       gchar* debug;
       GError* error;

packages/camera/elinux/gst_camera.h

@@ -1,4 +1,4 @@
-// Copyright 2021 Sony Group Corporation. All rights reserved.
+// Copyright 2022 Sony Group Corporation. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -7,6 +7,7 @@
 
 #include <gst/gst.h>
 
+#include <functional>
 #include <memory>
 #include <shared_mutex>
 #include <string>
@@ -15,6 +16,9 @@
 
 class GstCamera {
  public:
+  using OnNotifyCaptured =
+      std::function<void(const std::string& captured_file_path)>;
+
   GstCamera(std::unique_ptr<CameraStreamHandler> handler);
   ~GstCamera();
 
@@ -25,6 +29,8 @@ class GstCamera {
   bool Pause();
   bool Stop();
 
+  void TakePicture(OnNotifyCaptured on_notify_captured);
+
   bool SetZoomLevel(float zoom);
   float GetMaxZoomLevel() const { return max_zoom_level_; };
   float GetMinZoomLevel() const { return min_zoom_level_; };
@@ -59,10 +65,13 @@ class GstCamera {
   int32_t width_ = -1;
   int32_t height_ = -1;
   std::shared_mutex mutex_buffer_;
-  std::unique_ptr<CameraStreamHandler> stream_handler_;
+  std::unique_ptr<CameraStreamHandler> stream_handler_ = nullptr;
   float max_zoom_level_;
   float min_zoom_level_;
   float zoom_level_ = 1.0f;
+  int captured_count_ = 0;
+
+  OnNotifyCaptured on_notify_captured_ = nullptr;
 };
 
 #endif  // PACKAGES_CAMERA_CAMERA_ELINUX_GST_CAMERA_H_