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);