window_capture

    HDC     hScreen = GetDC(NULL);
    HDC     hDC = CreateCompatibleDC(hScreen);
    HBITMAP hBitmap = CreateCompatibleBitmap(hScreen, 1920, 1080);
    HGDIOBJ old_obj = SelectObject(hDC, hBitmap);
    BOOL    bRet = BitBlt(hDC, 0, 0, 1920, 1080, hScreen, 0, 0, SRCCOPY);

    constexpr size_t buffer_size = 1920 * 1080 * 4;

    std::vector<char> buffer(buffer_size);

    GetBitmapBits(hBitmap, buffer_size, buffer.data());

    CImg img(buffer.data(), 1920, 1080);
    CImgDisplay display(img);

    while (!display.is_closed())
    {
        display.wait(1000 / 60);
    }

    // clean up
    SelectObject(hDC, old_obj);
    DeleteDC(hDC);
    ReleaseDC(NULL, hScreen);
    DeleteObject(hBitmap);