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#define INCL_GPIREGIONS
 
LONG GpiCombineRegion(hps, hrgnDest, hrgnSrc1, hrgnSrc2, cmdMode)
HPS hps;          /* presentation-space handle      */
HRGN hrgnDest;    /* handle of destination region   */
HRGN hrgnSrc1;    /* handle of first source region  */
HRGN hrgnSrc2;    /* handle of second source region */
LONG cmdMode;     /* combination method             */
 
The GpiCombineRegion function combines two source regions identified by
hrgnSrc1 and hrgnSrc2. The new region replaces the destination region
identified by hrgnDest. If one of the source regions is also given as the
destination region, the function replaces that source region with the new
region, but does not affect the other source region.
 
Parameter  Description
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hps        Identifies the presentation space. The presentation space must be
           associated with a device context.
 
hrgnDest   Identifies the destination region.
 
hrgnSrc1   Identifies the first source region.
 
hrgnSrc2   Identifies the second source region.
 
cmdMode    Specifies how to combine the source regions. It can be one of the
           following values:
 
           Value      Meaning
           ─────────────────────────────────────────────────────────────────
           CRGN_AND   Creates the intersection of the source regions
                      (hrgnSrc1 INTERSECT hrgnSrc2). The new region contains
                      only the parts of the source regions that are common.
 
           CRGN_COPY  Copies the first source region to the destination. The
                      function does not use the hrgnSrc2 parameter.
 
           CRGN_DIFF  Creates the difference of the source region (hrgnSrc1
                      INTERSECT NOT hrgnSrc2). The new region contains the
                      parts of the first source region that are not also in
                      the second region.
 
           CRGN_OR    Creates the union of the two source regions (hrgnSrc1
                      UNION hrgnSrc2). The new region contains all parts of
                      both source regions.
 
           CRGN_XOR   Creates the "symmetric" difference of the source
                      regions (hrgnSrc1 - hrgnSrc2). The new region contains
                      only the parts of the source regions that are not
                      common.
 
Return Value
 
The return value is RGN_NULL, RGN_RECT, or REGN_COMPLEX if the function is
successful. The return value is RGN_ERROR if an error occurred.
 
Errors
 
Use the WinGetLastError function to retrieve the error value, which may be
one of the following:
 
     PMERR_INV_HPS
     PMERR_INV_HRGN
     PMERR_INV_REGION_MIX
     PMERR_INV_REGION_MIX_MODE
     PMERR_PS_BUSY
     PMERR_REGION_IS_CLIP_REGION
 
Comments
 
The source and destination regions must belong to the same presentation
space or to presentation spaces associated with a similar device context.
 
Example
 
This example uses the GpiCombineRegion function to create a complex region
consisting of everything in two rectangles except where they overlap.
 
HRGN hrgn1, hrgn2, hrgn3;
RECTL rclRect1 = { 0, 0, 100, 100 };
RECTL rclRect2 = { 50, 50, 200, 200 };
 
hrgn1 = GpiCreateRegion(hps, 1L, &rclRect1);    /* create first region  */
hrgn2 = GpiCreateRegion(hps, 1L, &rclRect2);    /* create second region */
hrgn3 = GpiCreateRegion(hps, 0L, (RECTL) NULL); /* create empty region  */
 
/* Combine first and second regions, replacing the empty region. */
 
GpiCombineRegion(hrgn3, hrgn1, hrgn2, CRGN_XOR);
 
See Also
 
GpiCreateRegion, WinGetLastError
 
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