GreCombineRegion

GreCombineRegion combines two regions to make a third. The destination region can be the same as one of the source regions. An error is raised when any one of the specified regions is currently selected as the clip region. All source and target regions must be of the same device class.

This function can be hooked by the presentation driver.

Simulation support: This function is simulated by a handling routine in the graphics engine.

Syntax

GreCombineRegion(hdc, hrgnDst, hrgnSrc1, hrgnSrc2, cmdMode, pInstance, lFunction);

Parameters

hdc (HDC) - input: Device context handle.

hrgnDst (HRGN) - input: Destination region handle.

hrgnSrc1 (HRGN) - input: First region handle.

hrgnSrc2 (HRGN) - input: Second region handle.

cmdMode (LONG) - input: Method of combination.

CRGN_OR: Union of hrgnSrc1 and hrgnSrc2.
CRGN_COPY: Uses hrgnSrc1 only. hrgnSrc2 is ignored.
CRGN_XOR: Symmetric difference of hrgnSrc1 and hrgnSrc2.
CRGN_AND: Intersection of hrgnSrc1 and hrgnSrc2.
CRGN_DIFF: Uses hrgnSrc1 and not (hrgnSrc2).

pInstance (PVOID) - input: Pointer to instance data.

lFunction (ULONG) - input: High-order WORD=flags; low-order WORD=NGreCombineRegion.

Returns

rc (LONG) - returns: This function returns an integer (lComplexity) indicating the complexity of the new region:

RGN_ERROR: Error
RGN_NULL: Null region
RGN_RECT: Rectangular region
RGN_COMPLEX: Complex region (more than 1 rectangle)

Possible Errors Detected: When an error is detected, the handling routine must call WinSetErrorInfo to post the condition. Error codes for conditions that the handling routine is expected to check include:

PMERR_HRGN_BUSY
PMERR_INSUFFICIENT_MEMORY
PMERR_INV_COORDINATE
PMERR_INV_HRGN
PMERR_INV_LENGTH_OR_COUNT
PMERR_INV_RECT
PMERR_REGION_IS_CLIP_REGION

Refer to the "Error Explanations" section in the Presentation Manager Programming Reference for further explanation.

Sample

#define INCL_GRE_REGIONS
#include <os2.h>

HDC      hdc;        /*  Device context handle. */
HRGN     hrgnDst;    /*  Destination region handle. */
HRGN     hrgnSrc1;   /*  First region handle. */
HRGN     hrgnSrc2;   /*  Second region handle. */
LONG     cmdMode;    /*  Method of combination. */
PVOID    pInstance;  /*  Pointer to instance data. */
ULONG    lFunction;  /*  High-order WORD=flags; low-order WORD=NGreCombineRegion. */
LONG     rc;

rc = GreCombineRegion(hdc, hrgnDst, hrgnSrc1,
       hrgnSrc2, cmdMode, pInstance, lFunction);