ExtSelectClipRgn
The ExtSelectClipRgn
function combines the specified region with the current clipping region by
using the specified mode.
int ExtSelectClipRgn(
|
HDC hdc, |
// handle to device
context |
|
HRGN hrgn, |
// handle to region
|
|
int fnMode |
// region-selection
mode |
|
); |
|
Parameters
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.
fnMode
Specifies the
operation to be performed. It must be one of the following values:
|
Value |
Meaning |
|
RGN_AND |
The new
clipping region combines the overlapping areas of the current clipping region
and the region identified by hrgn. |
|
RGN_COPY |
The new
clipping 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 clipping region is
the default clipping region (the default clipping region is a null region). |
|
RGN_DIFF |
The new
clipping region combines the areas of the current clipping region with those
areas excluded from the region identified by hrgn. |
|
RGN_OR |
The new
clipping region combines the current clipping region and the region
identified by hrgn. |
|
RGN_XOR |
The new
clipping region combines the current clipping region and the region
identified by hrgn but excludes any overlapping areas. |
Return Values
If the
function succeeds, the return value specifies the new clipping region s
complexity and 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 one rectangle. |
|
ERROR |
An error
occurred. |
Remarks
If an error
occurs when this function is called, the previous clipping region for the
specified device context is not affected.
The ExtSelectClipRgn
function assumes that the coordinates for the specified region are specified in
device units.
Only a copy
of the region identified by the hrgn parameter is used. The region
itself can be reused after this call or it can be deleted.
See Also