GetUpdateRgn
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4/8/2010
This 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.
Syntax
int GetUpdateRgn(
HWND hWnd,
HRGN hRgn,
BOOL bErase
);
Parameters
- hWnd
Handle to the window with an update region that is to be retrieved.
- hRgn
Handle to the region to receive the update region.
bErase
Boolean that 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 Value
The return value indicates the complexity of the resulting region.
COMPLEXREGION indicates that the region consists of more than one rectangle.
ERROR indicates that an error occurred.
NULLREGION indicates that the region is empty.
SIMPLEREGION indicates that the region is a single rectangle.
Remarks
The bErase parameter is ignored, the window background is not erased and no drawing is done.
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.
Requirements
| Header | winuser.h |
| Library | coredll.lib, Winmgr.lib |
| Windows Embedded CE | Windows CE 1.0 and later |
| Windows Mobile | Windows Mobile Version 5.0 and later |