GpiCorrelateSegment

This function performs a correlate operation on a specified segment.

Syntax

GpiCorrelateSegment(hps, lSegment, lType, pptlPick, lMaxHits, lMaxDepth, alSegTag)

Parameters

hps (HPS) - input

Presentation-space handle.

lSegment (LONG) - input

Identifier of the segment to be correlated.

It must be greater than 0.

lType (LONG) - input

Type of segments on which correlation is to be performed.

PICKSEL_VISIBLE: Only visible and detectable segments with nonzero identifiers are correlated.

PICKSEL_ALL: All segments with nonzero identifiers are correlated, regardless of the detectability and visibility attributes of the segments.

pptlPick (PPOINTL) - input

Pick position.

The position of the center of the pick aperture, in presentation page units.

lMaxHits (LONG) - input

Maximum hits.

The maximum number of hits that can be returned in the alSegTag parameter. It must be greater than 0.

lMaxDepth (LONG) - input

Number of pairs.

Number of segment/tag pairs to be returned by each hit. It must be greater than 0.

alSegTag (PLONG) - output

Segment identifiers and tags.

An array consisting of segment identifiers and primitive tags in alternate elements. For each hit, a set of lMaxDepth segment identifiers and tag pairs is returned.

Return Code

lNumHits (LONG) - returns

Number of hits and error indicators.

>=0 - Number of hits that occurred

GPI_ALTERROR - Error.

Errors

Possible returns from WinGetLastError

PMERR_INV_HPS (0x207F)

An invalid presentation-space handle was specified.

PMERR_PS_BUSY (0x20F4)

An attempt was made to access the presentation space from more than one thread simultaneously.

PMERR_INV_CORRELATE_TYPE (0x205D)

An invalid type parameter was specified with GpiCorrelateSegment, GpiCorrelateFrom, or GpiCorrelateChain.

PMERR_INV_COORDINATE (0x205B)

An invalid coordinate value was specified.

PMERR_INV_MAX_HITS (0x209C)

An invalid maxhits parameter was specified with GpiCorrelateSegment, GpiCorrelateFrom, or GpiCorrelateChain.

PMERR_INV_CORRELATE_DEPTH (0x205C)

An invalid maxdepth parameter was specified with GpiCorrelateSegment, GpiCorrelateFrom, or GpiCorrelateChain.

PMERR_INV_MICROPS_FUNCTION (0x20A1)

An attempt was made to issue a function that is invalid in a micro presentation space.

PMERR_SEG_NOT_FOUND (0x2100)

The specified segment identifier did not exist.

PMERR_INV_SEG_NAME (0x20C8)

An invalid segment identifier was specified.

Example Code

This example uses GpiCorrelateSegment to correlate, using an aperture of default size and centered at (200,200), on a visible and detectable segment and requests one intersection (or hit) and one segment/tag pair for that hit to be returned. The segment will have been previously defined and created using GpiSetInitialSegmentAttrs and GpiOpenSegment/GpiCloseSegment.

#define INCL_GPICORRELATION     /* GPI Correlation functions    */
#include <os2.h>

BOOL     fSuccess;      /* success indicator                    */
SIZEL    psizlSize;     /* size of pick aperture                */
LONG     lNumHits;      /* number of hits or error              */
HPS      hps;           /* Presentation-space handle            */
LONG     lSegment;      /* segment to be correlated             */
LONG     lLastSegment;  /* Specifies the last segment to be
                           correlated                           */
POINTL   pptlPick = {200L,200L};
                        /* Pick (center of aperture) position   */
LONG     lMaxHits;      /* Maximum hits to be returned          */
LONG     lMaxDepth;     /* Number of pairs to be returned       */
LONG     alSegTag;      /* Segment identifiers and tags         */

fSuccess = GpiSetPickAperturePosition(hps, &pptlPick);

/* set aperture size (use default) */
fSuccess = GpiSetPickApertureSize(hps, PICKAP_DEFAULT, &psizlSize);

/* define segment */
lSegment = 1;

/* return only one hit */
lMaxHits = 1L;

/* return only one segment/tag pair per hit */
lMaxDepth = 1L;

/* correlate on visible, detectable segments */
lNumHits = GpiCorrelateSegment(hps, lSegment, PICKSEL_VISIBLE,
                               &pptlPick, lMaxHits, lMaxDepth,
                               &alSegTag);

Related Functions

• GpiCallSegmentMatrix
• GpiCloseSegment
• GpiCorrelateChain
• GpiCorrelateFrom
• GpiDeleteSegment
• GpiDeleteSegments
• GpiDrawSegment
• GpiErrorSegmentData
• GpiOpenSegment
• GpiQueryInitialSegmentAttrs
• GpiQuerySegmentAttrs
• GpiQuerySegmentNames
• GpiQuerySegmentPriority
• GpiSetDrawControl
• GpiSetInitialSegmentAttrs
• GpiSetPickAperturePosition
• GpiSetPickApertureSize
• GpiSetSegmentAttrs
• GpiSetSegmentPriority