| int GetUpdateRgn(hwnd, hRgn, bErase) | |||||
| HWND hwnd; | /* handle of window | */ | |||
| HRGN hRgn; | /* handle of region | */ | |||
| BOOL bErase; | /* erase flag | */ | |||
This function copies a window's update region into a region identified by the hRgn parameter. The coordinates of this region are relative to the upper-left corner of the window (client coordinates).
hwnd
Identifies the window that contains the region to be updated.
hRgn
Identifies the update region.
bErase
Specifies whether or not the window background should be erased and nonclient areas of child windows should be drawn. If it is zero, no drawing is done.
The return value indicates the type of resulting region. It can be any one of the following values:
| 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. |
BeginPaint automatically validates the update region, so any call to GetUpdateRgn made immediately after the BeginPaint call retrieves an empty update region.
BeginPaint, GetUpdateRect