ExtSelectClipRgn function (wingdi.h)

The ExtSelectClipRgn function combines the specified region with the current clipping region using the specified mode.

Syntax

int ExtSelectClipRgn(
  [in] HDC  hdc,
  [in] HRGN hrgn,
  [in] int  mode
);

[in] hdc

A handle to the device context.

[in] hrgn

A handle to the region to be selected. This handle must not be NULL unless the RGN_COPY mode is specified.

[in] mode

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.

The return value specifies the new clipping region's complexity; it can be one of the following values.

Return code	Description
NULLREGION	Region is empty.
SIMPLEREGION	Region is a single rectangle.
COMPLEXREGION	Region is more than one rectangle.
ERROR	An error occurred.

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.

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	wingdi.h (include Windows.h)
Library	Gdi32.lib
DLL	Gdi32.dll