The GetClientRect function retrieves the coordinates of a window's client area. The client coordinates specify the upper-left and lower-right corners of the client area. Because client coordinates are relative to the upper-left corner of a window's client area, the coordinates of the upper-left corner are (0,0).
BOOL GetClientRect(
HWND hWnd, // handle to window
LPRECT lpRect // address of structure for client coordinates
);
If the function succeeds, the return value is nonzero.
If the function fails, the return value is zero. To get extended error information, call GetLastError.
Windows CE: Command bars are included in the client area.
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Requires version 1.0 or later.
Header: Declared in winuser.h.
Import Library: Use user32.lib.
Windows Overview, Window Functions, GetWindowRect, RECT