GetUpdateRgn
The GetUpdateRgn
function retrieves the update region of a window by copying it into the
specified region. The coordinates of the update region are relative to the
upper-left corner of the window (that is, they are client coordinates).
int GetUpdateRgn(
|
HWND hWnd, |
// handle of window |
|
HRGN hRgn, |
// handle of region |
|
BOOL bErase |
// erase background
flag |
|
); |
|
Parameters
hWnd
Identifies
the window with an update region that is to be retrieved.
hRgn
Identifies
the region to receive the update region.
bErase
Specifies
whether the window background should be erased and whether nonclient areas of
child windows should be drawn. If this parameter is FALSE, no drawing is done.
Return Values
The return
value indicates the complexity of the resulting region; it can be one of the
following values:
|
Value |
Meaning |
|
COMPLEXREGION |
Region
consists of more than one rectangle. |
|
ERROR |
An error
occurred. |
|
NULLREGION |
Region is
empty. |
|
SIMPLEREGION |
Region is a
single rectangle. |
Remarks
The BeginPaint function automatically
validates the update region, so any call to GetUpdateRgn made
immediately after the call to BeginPaint retrieves an empty update
region.
See Also