How to use SDL with Win32 Menus - c++

Question

This is a GameBoy emulator I've been working on for quite some time. It originally only worked on MacOS, but I've lately been working on a Windows port. I am using SDL for window creation and rendering. What I would like to do is create a normal Windows menu bar using Win32 API (CreateMenu, AppendMenu, etc). So far I can get the menu bar to exist on the Window, but I am trying to add callbacks using CALLBACK WndProc(), so the menu knows that you're clicking an option. This was not as successful. Anyone know how to do this?
This is the WinMain Entry Point:
/***************** INSTANCES *******************/
static Core::GameBoy* mGameBoy_Instance;
static FrontEnd::SDLContext* mSDL_Instance;
/***********************************************/
INT WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR lpCmdLine, INT nCmdShow)
{
// Load options
Core::Settings settings;
Util::CreateSettingsFromFile(OPTIONS_FILE_PATH, settings);
settings.skip_bootrom = true;
// Create the system instance
mGameBoy_Instance = new Core::GameBoy(settings, WIN_WIDTH, WIN_HEIGHT);
// Initalize Render Context
const char* windowTitle = mGameBoy_Instance->GetCurrentROM()->GetRomName();
mSDL_Instance = new FrontEnd::SDLContext(WIN_WIDTH, WIN_HEIGHT, WIN_SCALE, windowTitle);
// Initialize menubar
SDL_SysWMinfo sysInfo;
SDL_VERSION(&sysInfo.version);
SDL_GetWindowWMInfo(mSDL_Instance->GetWindow(), &sysInfo);
HWND hwnd = sysInfo.info.win.window;
/*********************************/
HMENU menubar = CreateMenu();
/*********************************/
HMENU file = CreateMenu();
HMENU exit = CreateMenu();
/*********************************/
AppendMenu(menubar, MF_POPUP, (UINT_PTR)file, "File");
AppendMenu(file, MF_STRING, (UINT_PTR)exit, "Exit");
SetMenu(hwnd, menubar);
// start sdl thread and main loop
}
And this is the callback function code:
LRESULT CALLBACK WndProc(_In_ HWND hwnd, _In_ UINT uMsg, _In_ WPARAM wParam, _In_ LPARAM lParam)
{
switch (uMsg) {
case WM_COMMAND:
{
switch (LOWORD(wParam)) {
case 2: // Should be the Exit button in the order of the menu
SendMessage(hwnd, WM_CLOSE, 0, 0);
break;
}
return 0;
}
case WM_DESTROY:
PostQuitMessage(0);
return 0;
default:
return DefWindowProcW(hwnd, uMsg, wParam, lParam);
}
return NULL;
}
When I do this, the callbacks aren't called.
Any help is appreciated.
Thanks!

Answer 1

You are assigning the exit HMENU as the ID of the item ou create for exit, that is not going to match "case 2:".
Get rid of the "HMENU exit" Make the call:
AppendMenu(file, MF_STRING, 2, _T("Exit"));
I would suggest that you assign some constant name (either #define or enum) and use that identifier in both the AppendMenu and case statement.

Answer 2

Normal menu items have numeric ids, not a HMENU handle. Submenus should be created with CreatePopupMenu, not CreateMenu:
#define ID_EXIT 50
...
HMENU menubar = CreateMenu();
HMENU filemenu = CreatePopupMenu();
AppendMenu(filemenu, MF_STRING, ID_EXIT, "Exit");
AppendMenu(menubar, MF_POPUP, (UINT_PTR) filemenu, "File");
SetMenu(hwnd, menubar);
...
case WM_COMMAND:
switch (LOWORD(wParam)) {
case ID_EXIT:
SendMessage(hwnd, WM_CLOSE, 0, 0);
break;
}
break;