win32-gui.c

// x86_64-w64-mingw32-gcc win32-gui.c && wine64 a.exe
// https://docs.microsoft.com/en-us/windows/win32/learnwin32/your-first-windows-program
#ifndef UNICODE
#define UNICODE
#endif

#include <windows.h>

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam);

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
                   LPSTR lpCmdLine, int nCmdShow) {
  const wchar_t CLASS_NAME[] = L"Sample Window Class";
  WNDCLASS wc = {.lpfnWndProc = WindowProc,
                 .hInstance = hInstance,
                 .lpszClassName = CLASS_NAME};
  RegisterClass(&wc);
  HWND hwnd =
      CreateWindowEx(0,                           // Optional window styles.
                     CLASS_NAME,                  // Window class
                     L"Learn to Program Windows", // Window text
                     WS_OVERLAPPEDWINDOW,         // Window style
                     // Size and position
                     CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,
                     NULL,      // Parent window
                     NULL,      // Menu
                     hInstance, // Instance handle
                     NULL       // Additional application data
      );
  if (!hwnd)
    return 1;
  ShowWindow(hwnd, nCmdShow);
  MSG msg = {};
  while (GetMessage(&msg, NULL, 0, 0)) {
    TranslateMessage(&msg);
    DispatchMessage(&msg);
  }
  return 0;
}

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam,
                            LPARAM lParam) {
  switch (uMsg) {
  case WM_DESTROY:
    PostQuitMessage(0);
    return 0;
  case WM_PAINT: {
    PAINTSTRUCT ps;
    HDC hdc = BeginPaint(hwnd, &ps);
    FillRect(hdc, &ps.rcPaint, (HBRUSH)(COLOR_WINDOW + 1));
    EndPaint(hwnd, &ps);
  }
    return 0;
  }
  return DefWindowProc(hwnd, uMsg, wParam, lParam);
}