C/Visual C - grafico

#include <windows.h>

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

    switch (uMsg) {

        case WM_PAINT: {

            PAINTSTRUCT ps;

            HDC hdc = BeginPaint(hwnd, &ps);

            // Limpiar la pantalla con un color de fondo

            FillRect(hdc, &ps.rcPaint, (HBRUSH)(COLOR_WINDOW + 1));

            // Dibujar un rectángulo rojo

            HBRUSH hBrush = CreateSolidBrush(RGB(255, 0, 0));

            SelectObject(hdc, hBrush);

            Rectangle(hdc, 50, 50, 200, 200);

            DeleteObject(hBrush);

            EndPaint(hwnd, &ps);

        } break;

        case WM_DESTROY:

            PostQuitMessage(0);

            return 0;

    }

    return DefWindowProc(hwnd, uMsg, wParam, lParam);

}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE, LPSTR, int nShowCmd) {

    const char CLASS_NAME[] = "MiClaseVentana";

    WNDCLASS wc = {};

    wc.lpfnWndProc = WindowProc;

    wc.hInstance = hInstance;

    wc.lpszClassName = CLASS_NAME;

    RegisterClass(&wc);

    HWND hwnd = CreateWindowEx(0, CLASS_NAME, "Ventana GDI", WS_OVERLAPPEDWINDOW,

                               CW_USEDEFAULT, CW_USEDEFAULT, 400, 400,

                               NULL, NULL, hInstance, NULL);

    ShowWindow(hwnd, nShowCmd);

    MSG msg;

    while (GetMessage(&msg, NULL, 0, 0)) {

        TranslateMessage(&msg);

        DispatchMessage(&msg);

    }

    return 0;

}