How to get the Monitor Screen Resolution from a hWnd?

The user32 function MonitorFromWindow allows you to pass in an hwnd, and returns a handle to the monitor it's on (or a default - see the linked MSDN article for details). With that you can call GetMonitorInfo to retrieve a MONITORINFO struct which contains a RECT detailing its resolution.

See the Multiple Screens Reference section of MSDN for more details.

I'd add example code but I don't know the language you referenced, and I don't know how useful C# example code would be to you. If you think it'll help, let me know and I'll code up something real quick.

Here's a C++ code example that works for me:

HMONITOR monitor = MonitorFromWindow(hwnd, MONITOR_DEFAULTTONEAREST);
MONITORINFO info;
info.cbSize = sizeof(MONITORINFO);
GetMonitorInfo(monitor, &info);
int monitor_width = info.rcMonitor.right - info.rcMonitor.left;
int monitor_height = info.rcMonitor.bottom - info.rcMonitor.top;