Dark window title for Windows (flet-dev#2204)

* Migrate Windows client to support dark window title

Fix flet-dev#2195

* Fixed Windows client

client/.metadata

@@ -1,23 +1,23 @@
 # This file tracks properties of this Flutter project.
 # Used by Flutter tool to assess capabilities and perform upgrades etc.
 #
-# This file should be version controlled.
+# This file should be version controlled and should not be manually edited.
 
 version:
-  revision: cd41fdd495f6944ecd3506c21e94c6567b073278
-  channel: stable
+  revision: "db7ef5bf9f59442b0e200a90587e8fa5e0c6336a"
+  channel: "stable"
 
 project_type: app
 
 # Tracks metadata for the flutter migrate command
 migration:
   platforms:
     - platform: root
-      create_revision: cd41fdd495f6944ecd3506c21e94c6567b073278
-      base_revision: cd41fdd495f6944ecd3506c21e94c6567b073278
-    - platform: linux
-      create_revision: cd41fdd495f6944ecd3506c21e94c6567b073278
-      base_revision: cd41fdd495f6944ecd3506c21e94c6567b073278
+      create_revision: db7ef5bf9f59442b0e200a90587e8fa5e0c6336a
+      base_revision: db7ef5bf9f59442b0e200a90587e8fa5e0c6336a
+    - platform: windows
+      create_revision: db7ef5bf9f59442b0e200a90587e8fa5e0c6336a
+      base_revision: db7ef5bf9f59442b0e200a90587e8fa5e0c6336a
 
   # User provided section
 

client/windows/CMakeLists.txt

@@ -1,13 +1,16 @@
+# Project-level configuration.
 cmake_minimum_required(VERSION 3.14)
 project(flet LANGUAGES CXX)
 
+# The name of the executable created for the application. Change this to change
+# the on-disk name of your application.
 set(BINARY_NAME "flet")
 
-cmake_policy(SET CMP0063 NEW)
+# Explicitly opt in to modern CMake behaviors to avoid warnings with recent
+# versions of CMake.
+cmake_policy(VERSION 3.14...3.25)
 
-set(CMAKE_INSTALL_RPATH "$ORIGIN/lib")
-
-# Configure build options.
+# Define build configuration option.
 get_property(IS_MULTICONFIG GLOBAL PROPERTY GENERATOR_IS_MULTI_CONFIG)
 if(IS_MULTICONFIG)
   set(CMAKE_CONFIGURATION_TYPES "Debug;Profile;Release"
@@ -20,7 +23,7 @@ else()
       "Debug" "Profile" "Release")
   endif()
 endif()
-
+# Define settings for the Profile build mode.
 set(CMAKE_EXE_LINKER_FLAGS_PROFILE "${CMAKE_EXE_LINKER_FLAGS_RELEASE}")
 set(CMAKE_SHARED_LINKER_FLAGS_PROFILE "${CMAKE_SHARED_LINKER_FLAGS_RELEASE}")
 set(CMAKE_C_FLAGS_PROFILE "${CMAKE_C_FLAGS_RELEASE}")
@@ -30,6 +33,10 @@ set(CMAKE_CXX_FLAGS_PROFILE "${CMAKE_CXX_FLAGS_RELEASE}")
 add_definitions(-DUNICODE -D_UNICODE)
 
 # Compilation settings that should be applied to most targets.
+#
+# Be cautious about adding new options here, as plugins use this function by
+# default. In most cases, you should add new options to specific targets instead
+# of modifying this function.
 function(APPLY_STANDARD_SETTINGS TARGET)
   target_compile_features(${TARGET} PUBLIC cxx_std_17)
   target_compile_options(${TARGET} PRIVATE /W4 /WX /wd"4100")
@@ -38,14 +45,14 @@ function(APPLY_STANDARD_SETTINGS TARGET)
   target_compile_definitions(${TARGET} PRIVATE "$<$<CONFIG:Debug>:_DEBUG>")
 endfunction()
 
-set(FLUTTER_MANAGED_DIR "${CMAKE_CURRENT_SOURCE_DIR}/flutter")
-
 # Flutter library and tool build rules.
+set(FLUTTER_MANAGED_DIR "${CMAKE_CURRENT_SOURCE_DIR}/flutter")
 add_subdirectory(${FLUTTER_MANAGED_DIR})
 
-# Application build
+# Application build; see runner/CMakeLists.txt.
 add_subdirectory("runner")
 
+
 # Generated plugin build rules, which manage building the plugins and adding
 # them to the application.
 include(flutter/generated_plugins.cmake)
@@ -80,6 +87,12 @@ if(PLUGIN_BUNDLED_LIBRARIES)
     COMPONENT Runtime)
 endif()
 
+# Copy the native assets provided by the build.dart from all packages.
+set(NATIVE_ASSETS_DIR "${PROJECT_BUILD_DIR}native_assets/windows/")
+install(DIRECTORY "${NATIVE_ASSETS_DIR}"
+   DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
+   COMPONENT Runtime)
+
 # Fully re-copy the assets directory on each build to avoid having stale files
 # from a previous install.
 set(FLUTTER_ASSET_DIR_NAME "flutter_assets")

client/windows/flutter/CMakeLists.txt

@@ -1,3 +1,4 @@
+# This file controls Flutter-level build steps. It should not be edited.
 cmake_minimum_required(VERSION 3.14)
 
 set(EPHEMERAL_DIR "${CMAKE_CURRENT_SOURCE_DIR}/ephemeral")

client/windows/runner/CMakeLists.txt

@@ -1,6 +1,11 @@
 cmake_minimum_required(VERSION 3.14)
 project(runner LANGUAGES CXX)
 
+# Define the application target. To change its name, change BINARY_NAME in the
+# top-level CMakeLists.txt, not the value here, or `flutter run` will no longer
+# work.
+#
+# Any new source files that you add to the application should be added here.
 add_executable(${BINARY_NAME} WIN32
   "flutter_window.cpp"
   "main.cpp"
@@ -10,8 +15,26 @@ add_executable(${BINARY_NAME} WIN32
   "Runner.rc"
   "runner.exe.manifest"
 )
+
+# Apply the standard set of build settings. This can be removed for applications
+# that need different build settings.
 apply_standard_settings(${BINARY_NAME})
+
+# Add preprocessor definitions for the build version.
+target_compile_definitions(${BINARY_NAME} PRIVATE "FLUTTER_VERSION=\"${FLUTTER_VERSION}\"")
+target_compile_definitions(${BINARY_NAME} PRIVATE "FLUTTER_VERSION_MAJOR=${FLUTTER_VERSION_MAJOR}")
+target_compile_definitions(${BINARY_NAME} PRIVATE "FLUTTER_VERSION_MINOR=${FLUTTER_VERSION_MINOR}")
+target_compile_definitions(${BINARY_NAME} PRIVATE "FLUTTER_VERSION_PATCH=${FLUTTER_VERSION_PATCH}")
+target_compile_definitions(${BINARY_NAME} PRIVATE "FLUTTER_VERSION_BUILD=${FLUTTER_VERSION_BUILD}")
+
+# Disable Windows macros that collide with C++ standard library functions.
 target_compile_definitions(${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.
 add_dependencies(${BINARY_NAME} flutter_assemble)

client/windows/runner/flutter_window.cpp

@@ -26,6 +26,16 @@ bool FlutterWindow::OnCreate() {
   }
   RegisterPlugins(flutter_controller_->engine());
   SetChildContent(flutter_controller_->view()->GetNativeWindow());
+
+  flutter_controller_->engine()->SetNextFrameCallback([&]() {
+    this->Show();
+  });
+
+  // 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;
 }
 

client/windows/runner/main.cpp

@@ -27,7 +27,7 @@ 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"Flet", origin, size)) {
+  if (!window.Create(L"Flet", origin, size)) {
     return EXIT_FAILURE;
   }
   window.SetQuitOnClose(true);

client/windows/runner/runner.exe.manifest

@@ -7,7 +7,7 @@
   </application>
   <compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1">
     <application>
-      <!-- Windows 10 -->
+      <!-- Windows 10 and Windows 11 -->
       <supportedOS Id="{8e0f7a12-bfb3-4fe8-b9a5-48fd50a15a9a}"/>
       <!-- Windows 8.1 -->
       <supportedOS Id="{1f676c76-80e1-4239-95bb-83d0f6d0da78}"/>

client/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);
-  if (target_length == 0) {
-    return std::string();
-  }
+      -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()) {
+    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();
   }

client/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 =
@@ -126,9 +144,15 @@ 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,
@@ -188,6 +212,10 @@ Win32Window::MessageHandler(HWND hwnd,
         SetFocus(child_content_);
       }
       return 0;
+
+    case WM_DWMCOLORIZATIONCOLORCHANGED:
+      UpdateTheme(hwnd);
+      return 0;
   }
 
   return DefWindowProc(window_handle_, message, wparam, lparam);
@@ -243,3 +271,18 @@ 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));
+  }
+}

client/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.