CombineRgn

The CombineRgn function combines two regions and stores the result in a third region. The two regions are combined according to the specified mode. 

int CombineRgn(
  HRGN hrgnDest,      // handle to destination region
  HRGN hrgnSrc1,      // handle to source region
  HRGN hrgnSrc2,      // handle to source region
  int fnCombineMode   // region combining mode
);

Parameters

hrgnDest
Handle to a new region with dimensions defined by combining two other regions. (This region must exist before CombineRgn is called.)
hrgnSrc1
Handle to the first of two regions to be combined.
hrgnSrc2
Handle to the second of two regions to be combined.
fnCombineMode
Specifies a mode indicating how the two regions will be combined. This parameter can be one of the following values:
Value Description
RGN_AND Creates the intersection of the two combined regions.
RGN_COPY Creates a copy of the region identified by hrgnSrc1.
RGN_DIFF Combines the parts of hrgnSrc1 that are not part of hrgnSrc2.
RGN_OR Creates the union of two combined regions.
RGN_XOR Creates the union of two combined regions except for any overlapping areas.

Return Values

The return value specifies the type of the resulting region. It can be one of the following values:

Value Meaning
NULLREGION The region is empty.
SIMPLEREGION The region is a single rectangle.
COMPLEXREGION The region is more than a single rectangle.
ERROR No region is created.

Remarks

The three regions need not be distinct. For example, the hrgnSrc1 parameter can equal the hrgnDest parameter.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Requires version 1.0 or later.
  Header: Declared in wingdi.h.
  Import Library: Use gdi32.lib.

See Also

Regions Overview, Region Functions, CreateEllipticRgn, CreateEllipticRgnIndirect, CreatePolygonRgn, CreatePolyPolygonRgn, CreateRectRgn, CreateRectRgnIndirect, CreateRoundRectRgn