fix(windows): fix TitleBar buttons does not display correctly #415

Author: lijy91

windows/window_manager.cpp

@@ -28,7 +28,26 @@
 #define STATE_FULLSCREEN_ENTERED 3
 #define STATE_DOCKED 4
 
-#define DWMWA_USE_IMMERSIVE_DARK_MODE 19
+/// Window attribute that enables dark mode window decorations.
+///
+/// Redefined in case the developer's machine has a Windows SDK older than
+/// version 10.0.22000.0.
+/// See:
+/// https://docs.microsoft.com/windows/win32/api/dwmapi/ne-dwmapi-dwmwindowattribute
+#ifndef DWMWA_USE_IMMERSIVE_DARK_MODE
+#define DWMWA_USE_IMMERSIVE_DARK_MODE 20
+#endif
+
+constexpr const wchar_t kWindowClassName[] = L"FLUTTER_RUNNER_WIN32_WINDOW";
+
+/// Registry key for app theme preference.
+///
+/// A value of 0 indicates apps should use dark mode. A non-zero or missing
+/// value indicates apps should use light mode.
+constexpr const wchar_t kGetPreferredBrightnessRegKey[] =
+    L"Software\\Microsoft\\Windows\\CurrentVersion\\Themes\\Personalize";
+constexpr const wchar_t kGetPreferredBrightnessRegValue[] =
+    L"AppsUseLightTheme";
 
 #define APPBAR_CALLBACK WM_USER + 0x01;
 
@@ -1001,14 +1020,21 @@ void WindowManager::SetOpacity(const flutter::EncodableMap& args) {
 }
 
 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));
+  DWORD light_mode;
+  DWORD light_mode_size = sizeof(light_mode);
+  LSTATUS result =
+      RegGetValue(HKEY_CURRENT_USER, kGetPreferredBrightnessRegKey,
+                  kGetPreferredBrightnessRegValue, RRF_RT_REG_DWORD, nullptr,
+                  &light_mode, &light_mode_size);
+
+  if (result == ERROR_SUCCESS) {
+    std::string brightness =
+        std::get<std::string>(args.at(flutter::EncodableValue("brightness")));
+    HWND hWnd = GetMainWindow();
+    BOOL enable_dark_mode = light_mode == 0 && brightness == "dark";
+    DwmSetWindowAttribute(hWnd, DWMWA_USE_IMMERSIVE_DARK_MODE,
+                          &enable_dark_mode, sizeof(enable_dark_mode));
+  }
 }
 
 void WindowManager::SetIgnoreMouseEvents(const flutter::EncodableMap& args) {