WM_WINDOWPOSCHANGING
The
WM_WINDOWPOSCHANGING message is sent to a window whose size, position, or place
in the Z order is about to change as a result of a call to the SetWindowPos function or another
window-management function.
WM_WINDOWPOSCHANGING
lpwp = (LPWINDOWPOS) lParam; // points to size and
position data
Parameters
lpwp
Value of lParam.
Points to a WINDOWPOS
structure that contains information about the window s new size and position.
Return Values
If an
application processes this message, it should return zero.
Default Action
For a window
with the WS_OVERLAPPED or WS_THICKFRAME style, the DefWindowProc function sends the
WM_GETMINMAXINFO message to the window. This is done to validate the new size
and position of the window and to enforce the CS_BYTEALIGNCLIENT and
CS_BYTEALIGNWINDOW client styles. By not passing the WM_WINDOWPOSCHANGING
message to the DefWindowProc function, an application can override these
defaults.
Remarks
While this
message is being processed, modifying any of the values in WINDOWPOS
affects the window s new size, position, or place in the Z order. An
application can prevent changes to the window by setting or clearing the
appropriate bits in the flags member of WINDOWPOS.
See Also