Arduino

// для Windows Vista или выше
#define LOGPIXELSY 90
external(INT, "SetProcessDPIAware", "SetProcessDPIAware", "User32.dll");
external(INT, "GetDeviceCaps", "GetDeviceCaps", "Gdi32.dll");
external(INT, "ReleaseDC", "ReleaseDC", "User32.dll");
external(INT, "GetDC", "GetDC", "User32.dll");
SetProcessDPIAware();

int HDC = GetDC(0);
messagebox(GetDeviceCaps (HDC, LOGPIXELSY) / 0.96);
ReleaseDC(0, HDC);