int GetUpdateRgn( CRgn* pRgn, BOOL bErase = FALSE );
pRgn
Identifies the update region.
bErase
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.
Retrieves the update region into a region identified by pRgn. 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.
Specifies a short-integer flag that indicates the type of resulting region. The value can take any one of the following:
| Value | Meaning |
| COMPLEXREGION | The region has overlapping borders. |
| ERROR | No region was created. |
| NULLREGION | The region is empty. |
| SIMPLEREGION | The region has no overlapping borders. |
CWnd::BeginPaint, ::GetUpdateRgn