This documentation is archived and is not being maintained.


Retrieves the update region into a region identified by pRgn.

int GetUpdateRgn(
   CRgn* pRgn,
   BOOL bErase = FALSE 



Identifies the update region.


Specifies whether the background will be erased and nonclient areas of child windows will be drawn. If the value is FALSE, no drawing is done.

Specifies a short-integer flag that indicates the type of resulting region. The value can take any one of the following:

  • SIMPLEREGION   The region has no overlapping borders.

  • COMPLEXREGION   The region has overlapping borders.

  • NULLREGION   The region is empty.

  • ERROR   No region was created.

The coordinates of this region are relative to the upper-left corner (client coordinates).

The BeginPaint member function automatically validates the update region, so any call to GetUpdateRgn made immediately after a call to BeginPaint retrieves an empty update region.