Refactor Windows runner to remove custom window classes

Deleted custom Win32Window and FlutterWindow implementations, updating CMakeLists and main.cpp to use FlutterEngine directly. This simplifies the Windows runner code and removes unnecessary abstraction layers, relying on the Flutter engine for window management.

Author: lijy91

examples/multiple_window_example/windows/flutter/CMakeLists.txt

@@ -2,6 +2,7 @@
 cmake_minimum_required(VERSION 3.14)
 
 set(EPHEMERAL_DIR "${CMAKE_CURRENT_SOURCE_DIR}/ephemeral")
+set(CMAKE_CXX_STANDARD 20)
 
 # Configuration provided via flutter tool.
 include(${EPHEMERAL_DIR}/generated_config.cmake)
@@ -51,7 +52,6 @@ list(APPEND CPP_WRAPPER_SOURCES_PLUGIN
 list(TRANSFORM CPP_WRAPPER_SOURCES_PLUGIN PREPEND "${WRAPPER_ROOT}/")
 list(APPEND CPP_WRAPPER_SOURCES_APP
   "flutter_engine.cc"
-  "flutter_view_controller.cc"
 )
 list(TRANSFORM CPP_WRAPPER_SOURCES_APP PREPEND "${WRAPPER_ROOT}/")
 

examples/multiple_window_example/windows/runner/CMakeLists.txt

@@ -7,10 +7,8 @@ project(runner LANGUAGES CXX)
 #
 # Any new source files that you add to the application should be added here.
 add_executable(${BINARY_NAME} WIN32
-  "flutter_window.cpp"
   "main.cpp"
   "utils.cpp"
-  "win32_window.cpp"
   "${FLUTTER_MANAGED_DIR}/generated_plugin_registrant.cc"
   "Runner.rc"
   "runner.exe.manifest"
@@ -33,7 +31,6 @@ 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.

examples/multiple_window_example/windows/runner/flutter_window.cpp

@@ -1,12 +1,11 @@
 #include <flutter/dart_project.h>
-#include <flutter/flutter_view_controller.h>
-#include <windows.h>
+#include <flutter/flutter_engine.h>
+#include <flutter/generated_plugin_registrant.h>
 
-#include "flutter_window.h"
 #include "utils.h"
 
 int APIENTRY wWinMain(_In_ HINSTANCE instance, _In_opt_ HINSTANCE prev,
-                      _In_ wchar_t *command_line, _In_ int show_command) {
+                      _In_ wchar_t* command_line, _In_ int show_command) {
   // Attach to console when present (e.g., 'flutter run') or create a
   // new console when running with a debugger.
   if (!::AttachConsole(ATTACH_PARENT_PROCESS) && ::IsDebuggerPresent()) {
@@ -19,18 +18,13 @@ int APIENTRY wWinMain(_In_ HINSTANCE instance, _In_opt_ HINSTANCE prev,
 
   flutter::DartProject project(L"data");
 
-  std::vector<std::string> command_line_arguments =
-      GetCommandLineArguments();
+  auto command_line_arguments{GetCommandLineArguments()};
 
   project.set_dart_entrypoint_arguments(std::move(command_line_arguments));
 
-  FlutterWindow window(project);
-  Win32Window::Point origin(10, 10);
-  Win32Window::Size size(1280, 720);
-  if (!window.Create(L"multiple_window_example", origin, size)) {
-    return EXIT_FAILURE;
-  }
-  window.SetQuitOnClose(true);
+  auto const engine{std::make_shared<flutter::FlutterEngine>(project)};
+  RegisterPlugins(engine.get());
+  engine->Run();
 
   ::MSG msg;
   while (::GetMessage(&msg, nullptr, 0, 0)) {

examples/multiple_window_example/windows/runner/flutter_window.h

@@ -2,7 +2,6 @@
 // Microsoft Visual C++ generated include file.
 // Used by Runner.rc
 //
-#define IDI_APP_ICON                    101
 
 // Next default values for new objects
 //

examples/multiple_window_example/windows/runner/main.cpp

@@ -49,15 +49,14 @@ std::string Utf8FromUtf16(const wchar_t* utf16_string) {
       CP_UTF8, WC_ERR_INVALID_CHARS, utf16_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,
-      input_length, utf8_string.data(), target_length, nullptr, nullptr);
+      -1, utf8_string.data(), target_length, nullptr, nullptr);
   if (converted_length == 0) {
     return std::string();
   }