| int ExtSelectClipRgn(hdc, hrgn, iMode) | |||||
| HDC hdc; | /* handle of device context | */ | |||
| HRGN hrgn; | /* handle of region | */ | |||
| int iMode; | /* region-selection mode | */ | |||
The ExtSelectClipRgn function combines the given region with the current clip region using the specified mode.
hdc
Identifies the device context.
hrgn
Identifies the region to be selected. This handle can only be NULL when the RGN_COPY mode is specified.
iMode
Specifies the operation to be performed. It must be one of the following values:
| Type | Meaning |
| RGN_AND | The new clip-region combines the overlapping areas of the current clip region and the region identified by hrgn. |
| RGN_COPY | The new clip-region is a copy of the region identified by hrgn. This is identical to SelectClipRgn. If the region identified by hrgn is NULL, the new clip region is the default clip region (the default clip region is a null or empty region). |
| RGN_DIFF | The new clip region combines the areas of the current clip region with those areas excluded from the region identified by hrgn. |
| RGN_OR | The new clip region combines the current clip region and the region identified by hrgn. |
| RGN_XOR | The new clip region combines the current clip region and the region identified by hrgn but excludes any overlapping areas. |
The return value specifies the new clip region's complexity if the function is successful. It can be any one of the following values:
| Value | Meaning |
| NULLREGION | Region is empty. |
| SIMPLEREGION | Region is a single rectangle. |
| COMPLEXREGION | Region is more than a single rectangle. |
| ERROR | Error occurred. |
If an error occurs when this function is called, the previous clip region for the given device context is not affected.
The ExtSelectClipRgn function assumes that the coordinates for the given region are specified in device units.
Only a copy of the given region identified by hrgn is used. The region itself can be reused after this call, or it can be deleted.
SelectClipRgn