Merge pull request #589 from 4ster1sk/fix/titlebar-color

[Windows] ウィンドウタイトルと各種ボタンがタイトルバーの色と同じになる問題の修正

lib/main.dart

@@ -40,13 +40,14 @@ class MyApp extends ConsumerStatefulWidget {
   ConsumerState<MyApp> createState() => _MyAppState();
 }
 
-class _MyAppState extends ConsumerState<MyApp> with WindowListener {
+class _MyAppState extends ConsumerState<MyApp> with WindowListener, WidgetsBindingObserver {
   final _appRouter = AppRouter();
   final isDesktop = Platform.isWindows || Platform.isMacOS || Platform.isLinux;
 
   @override
   void initState() {
     if (isDesktop) {
+      WidgetsBinding.instance.addObserver(this);
       windowManager.addListener(this);
       unawaited(() async {
         await ref.read(desktopSettingsRepositoryProvider).load();
@@ -59,6 +60,7 @@ class _MyAppState extends ConsumerState<MyApp> with WindowListener {
   @override
   void dispose() {
     if (isDesktop) {
+      WidgetsBinding.instance.removeObserver(this);
       windowManager.removeListener(this);
     }
     super.dispose();
@@ -92,6 +94,19 @@ class _MyAppState extends ConsumerState<MyApp> with WindowListener {
     }
   }
 
+  @override
+  Future<void> didChangePlatformBrightness() async {
+    super.didChangePlatformBrightness();
+    if (!isDesktop) return;
+
+    final brightness =
+        WidgetsBinding.instance.platformDispatcher.platformBrightness;
+
+    /// Set up window brightness follow system theme mode.
+    await WindowManager.instance.setBrightness(brightness);
+    await WindowManager.instance.setTitleBarStyle(TitleBarStyle.normal);
+  }
+
   Future<void> _initWindow() async {
     await windowManager.setPreventClose(true);
     final config = ref.read(desktopSettingsRepositoryProvider).settings;
@@ -107,7 +122,6 @@ class _MyAppState extends ConsumerState<MyApp> with WindowListener {
     final opt = WindowOptions(
       size: size,
       center: position == null,
-      backgroundColor: Colors.transparent,
       skipTaskbar: false,
       titleBarStyle: TitleBarStyle.normal,
     );

windows/runner/CMakeLists.txt

@@ -33,6 +33,7 @@ target_compile_definitions(${BINARY_NAME} PRIVATE "NOMINMAX")
 # Add dependency libraries and include directories. Add any application-specific
 # dependencies here.
 target_link_libraries(${BINARY_NAME} PRIVATE flutter flutter_wrapper_app)
+target_link_libraries(${BINARY_NAME} PRIVATE "dwmapi.lib")
 target_include_directories(${BINARY_NAME} PRIVATE "${CMAKE_SOURCE_DIR}")
 
 # Run the Flutter tool portions of the build. This must not be removed.

windows/runner/flutter_window.cpp

@@ -26,6 +26,15 @@ bool FlutterWindow::OnCreate() {
   }
   RegisterPlugins(flutter_controller_->engine());
   SetChildContent(flutter_controller_->view()->GetNativeWindow());
+
+  flutter_controller_->engine()->SetNextFrameCallback([&]() {
+  });
+
+  // Flutter can complete the first frame before the "show window" callback is
+  // registered. The following call ensures a frame is pending to ensure the
+  // window is shown. It is a no-op if the first frame hasn't completed yet.
+  flutter_controller_->ForceRedraw();
+
   return true;
 }
 

windows/runner/main.cpp

@@ -26,8 +26,8 @@ int APIENTRY wWinMain(_In_ HINSTANCE instance, _In_opt_ HINSTANCE prev,
 
   FlutterWindow window(project);
   Win32Window::Point origin(10, 10);
-  Win32Window::Size size(1280, 720);
-  if (!window.CreateAndShow(L"miria", origin, size)) {
+  Win32Window::Size size(400, 700);
+  if (!window.Create(L"miria", origin, size)) {
     return EXIT_FAILURE;
   }
   window.SetQuitOnClose(true);

windows/runner/utils.cpp

@@ -47,16 +47,17 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
   }
   int target_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, nullptr, 0, nullptr, nullptr);
+      -1, nullptr, 0, nullptr, nullptr)
+    -1; // remove the trailing null character
+  int input_length = (int)wcslen(utf16_string);
   std::string utf8_string;
-  if (target_length == 0 || target_length > utf8_string.max_size()) {
+  if (target_length <= 0 || target_length > utf8_string.max_size()) {
     return utf8_string;
   }
   utf8_string.resize(target_length);
   int converted_length = ::WideCharToMultiByte(
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string,
-      -1, utf8_string.data(),
-      target_length, nullptr, nullptr);
+      input_length, utf8_string.data(), target_length, nullptr, nullptr);
   if (converted_length == 0) {
     return std::string();
   }

windows/runner/win32_window.cpp

@@ -1,13 +1,31 @@
 #include "win32_window.h"
 
+#include <dwmapi.h>
 #include <flutter_windows.h>
 
 #include "resource.h"
 
 namespace {
 
+/// 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";
+
 // The number of Win32Window objects that currently exist.
 static int g_active_window_count = 0;
 
@@ -31,8 +49,8 @@ void EnableFullDpiSupportIfAvailable(HWND hwnd) {
           GetProcAddress(user32_module, "EnableNonClientDpiScaling"));
   if (enable_non_client_dpi_scaling != nullptr) {
     enable_non_client_dpi_scaling(hwnd);
-    FreeLibrary(user32_module);
   }
+  FreeLibrary(user32_module);
 }
 
 }  // namespace
@@ -42,7 +60,7 @@ class WindowClassRegistrar {
  public:
   ~WindowClassRegistrar() = default;
 
-  // Returns the singleton registar instance.
+  // Returns the singleton registrar instance.
   static WindowClassRegistrar* GetInstance() {
     if (!instance_) {
       instance_ = new WindowClassRegistrar();
@@ -102,9 +120,9 @@ Win32Window::~Win32Window() {
   Destroy();
 }
 
-bool Win32Window::CreateAndShow(const std::wstring& title,
-                                const Point& origin,
-                                const Size& size) {
+bool Win32Window::Create(const std::wstring& title,
+                         const Point& origin,
+                         const Size& size) {
   Destroy();
 
   const wchar_t* window_class =
@@ -127,9 +145,15 @@ bool Win32Window::CreateAndShow(const std::wstring& title,
     return false;
   }
 
+  UpdateTheme(window);
+
   return OnCreate();
 }
 
+bool Win32Window::Show() {
+  return ShowWindow(window_handle_, SW_SHOWNORMAL);
+}
+
 // static
 LRESULT CALLBACK Win32Window::WndProc(HWND const window,
                                       UINT const message,
@@ -189,6 +213,10 @@ Win32Window::MessageHandler(HWND hwnd,
         SetFocus(child_content_);
       }
       return 0;
+
+    case WM_DWMCOLORIZATIONCOLORCHANGED:
+      UpdateTheme(hwnd);
+      return 0;
   }
 
   return DefWindowProc(window_handle_, message, wparam, lparam);
@@ -244,3 +272,18 @@ bool Win32Window::OnCreate() {
 void Win32Window::OnDestroy() {
   // No-op; provided for subclasses.
 }
+
+void Win32Window::UpdateTheme(HWND const window) {
+  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) {
+    BOOL enable_dark_mode = light_mode == 0;
+    DwmSetWindowAttribute(window, DWMWA_USE_IMMERSIVE_DARK_MODE,
+                          &enable_dark_mode, sizeof(enable_dark_mode));
+  }
+}

windows/runner/win32_window.h

@@ -28,15 +28,16 @@ class Win32Window {
   Win32Window();
   virtual ~Win32Window();
 
-  // Creates and shows a win32 window with |title| and position and size using
+  // Creates a win32 window with |title| that is positioned and sized using
   // |origin| and |size|. New windows are created on the default monitor. Window
   // sizes are specified to the OS in physical pixels, hence to ensure a
-  // consistent size to will treat the width height passed in to this function
-  // as logical pixels and scale to appropriate for the default monitor. Returns
-  // true if the window was created successfully.
-  bool CreateAndShow(const std::wstring& title,
-                     const Point& origin,
-                     const Size& size);
+  // consistent size this function will scale the inputted width and height as
+  // as appropriate for the default monitor. The window is invisible until
+  // |Show| is called. Returns true if the window was created successfully.
+  bool Create(const std::wstring& title, const Point& origin, const Size& size);
+
+  // Show the current window. Returns true if the window was successfully shown.
+  bool Show();
 
   // Release OS resources associated with window.
   void Destroy();
@@ -76,7 +77,7 @@ class Win32Window {
   // OS callback called by message pump. Handles the WM_NCCREATE message which
   // is passed when the non-client area is being created and enables automatic
   // non-client DPI scaling so that the non-client area automatically
-  // responsponds to changes in DPI. All other messages are handled by
+  // responds to changes in DPI. All other messages are handled by
   // MessageHandler.
   static LRESULT CALLBACK WndProc(HWND const window,
                                   UINT const message,
@@ -86,6 +87,9 @@ class Win32Window {
   // Retrieves a class instance pointer for |window|
   static Win32Window* GetThisFromHandle(HWND const window) noexcept;
 
+  // Update the window frame's theme to match the system theme.
+  static void UpdateTheme(HWND const window);
+
   bool quit_on_close_ = false;
 
   // window handle for top level window.