[windows] Implement setBrightness method #86

Author: lijy91

lib/src/window_manager.dart

@@ -557,7 +557,6 @@ class WindowManager {
     final Map<String, dynamic> arguments = {
       'brightness': brightness.name,
     };
-    print(arguments);
     await _channel.invokeMethod('setBrightness', arguments);
   }
 

windows/window_manager.cpp

@@ -22,6 +22,8 @@
 #define STATE_MINIMIZED 2
 #define STATE_FULLSCREEN_ENTERED 3
 
+#define DWMWA_USE_IMMERSIVE_DARK_MODE 19
+
 namespace {
 class WindowManager {
  public:
@@ -93,6 +95,7 @@ class WindowManager {
   void WindowManager::SetHasShadow(const flutter::EncodableMap& args);
   double WindowManager::GetOpacity();
   void WindowManager::SetOpacity(const flutter::EncodableMap& args);
+  void WindowManager::SetBrightness(const flutter::EncodableMap& args);
   void WindowManager::StartDragging();
   void WindowManager::StartResizing(const flutter::EncodableMap& args);
   flutter::EncodableMap WindowManager::GetPrimaryDisplay(
@@ -620,6 +623,17 @@ void WindowManager::SetOpacity(const flutter::EncodableMap& args) {
                              0x02);
 }
 
+void WindowManager::SetBrightness(const flutter::EncodableMap& args) {
+  std::string brightness =
+      std::get<std::string>(args.at(flutter::EncodableValue("brightness")));
+
+  const BOOL is_dark_mode = brightness == "dark";
+
+  HWND hWnd = GetMainWindow();
+  DwmSetWindowAttribute(hWnd, DWMWA_USE_IMMERSIVE_DARK_MODE, &is_dark_mode,
+                        sizeof(is_dark_mode));
+}
+
 void WindowManager::StartDragging() {
   ReleaseCapture();
   SendMessage(GetMainWindow(), WM_SYSCOMMAND, SC_MOVE | HTCAPTION, 0);

windows/window_manager_plugin.cpp

@@ -434,6 +434,11 @@ void WindowManagerPlugin::HandleMethodCall(
         std::get<flutter::EncodableMap>(*method_call.arguments());
     window_manager->SetOpacity(args);
     result->Success(flutter::EncodableValue(true));
+  } else if (method_name.compare("setBrightness") == 0) {
+    const flutter::EncodableMap& args =
+        std::get<flutter::EncodableMap>(*method_call.arguments());
+    window_manager->SetBrightness(args);
+    result->Success(flutter::EncodableValue(true));
   } else if (method_name.compare("startDragging") == 0) {
     window_manager->StartDragging();
     result->Success(flutter::EncodableValue(true));