MapWindowPoints

The MapWindowPoints function converts (maps) a set of points from a coordinate space relative to one window to a coordinate space relative to another window.

int MapWindowPoints(
  HWND hWndFrom, // handle of window to be mapped from
  HWND hWndTo,       // handle to window to be mapped to
  LPPOINT lpPoints,  // pointer to array with points to map
  UINT cPoints       // number of structures in array
);
 

Parameters

hWndFrom

Handle to the window from which points are converted. If this parameter is NULL or HWND_DESKTOP, the points are presumed to be in screen coordinates.

hWndTo

Handle to the window to which points are converted. If this parameter is NULL or HWND_DESKTOP, the points are converted to screen coordinates.

lpPoints

Pointer to an array of POINT structures that contain the set of points to be converted. This parameter can also point to a RECT structure, in which case the cPoints parameter should be set to 2.

cPoints

Specifies the number of POINT structures in the array pointed to by the lpPoints parameter.

Return Values

If the function succeeds, the low-order word of the return value is the number of pixels added to the horizontal coordinate of each source point in order to compute the horizontal coordinate of each destination point; the high-order word is the number of pixels added to the vertical coordinate of each source point in order to compute the vertical coordinate of each destination point.

If the function fails, the return value is zero.

Windows NT: To get extended error information, call GetLastError.

QuickInfo

  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.

See Also

Coordinate Spaces and Transformations Overview, Coordinate Space and Transformation Functions, ClientToScreen, POINT, RECT, ScreenToClient