Minimal Win32 sample

win32.cpp

#define WIN32_LEAN_AND_MEAN
#include <windows.h>

LRESULT CALLBACK WndProc(HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam);
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow);

int main(int argc, char** argv) {
	return WinMain(GetModuleHandle(NULL), NULL, GetCommandLineA(), SW_SHOWDEFAULT);
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) {
	WNDCLASSA wndclass;
	wndclass.style = CS_HREDRAW | CS_VREDRAW;
	wndclass.lpfnWndProc = WndProc;
	wndclass.cbClsExtra = 0;
	wndclass.cbWndExtra = 0;
	wndclass.hInstance = hInstance;
	wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
	wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);
	wndclass.hbrBackground = (HBRUSH)(COLOR_BTNFACE + 1);
	wndclass.lpszMenuName = 0;
	wndclass.lpszClassName = "GDI_Sample";
	RegisterClassA(&wndclass);

	int windowWidth = 800;
	int windowHeight = 600;

	RECT rClient;
	SetRect(&rClient, 0, 0, windowWidth, windowHeight);
	AdjustWindowRect(&rClient, WS_OVERLAPPEDWINDOW | WS_VISIBLE, FALSE);

	int screenWidth = GetSystemMetrics(SM_CXSCREEN);
	int screenHeight = GetSystemMetrics(SM_CYSCREEN);
	windowWidth = rClient.right - rClient.left;
	windowHeight = rClient.right - rClient.left;

	HWND hwnd = CreateWindowA(wndclass.lpszClassName, (char*)"Window Title", WS_OVERLAPPEDWINDOW | WS_VISIBLE,
		(screenWidth / 2) - (windowWidth / 2), (screenHeight / 2) - (windowHeight / 2),
		windowWidth, windowHeight, NULL, NULL, hInstance, 0);

	ShowWindow(hwnd, SW_NORMAL);
	UpdateWindow(hwnd);

	MSG msg;
	bool quit = false;

	while (!quit) {
		while (PeekMessageA(&msg, 0, 0, 0, PM_REMOVE)) {
			if (msg.message == WM_QUIT) {
				quit = true;
				break;
			}
			if (msg.hwnd == hwnd) {
				TranslateMessage(&msg);
				DispatchMessageA(&msg);
			}
		}
		
		Sleep(1);
	}

	return (int)msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam) {
	switch (iMsg) {
	case WM_CLOSE:
		DestroyWindow(hwnd);
		return 0;
	case WM_DESTROY:
		PostQuitMessage(0);
		return 0;
	}
	return DefWindowProcA(hwnd, iMsg, wParam, lParam);
}