GreCombineShortLineRegion

GreCombineShortLineRegion combines an area lying between polyshortline pairs, which is represented by a SCANDATA structure, with a region. The pScanData parameter is ORed into the region. This function is used to build regions for path simulation. The function always expects the points in the shortlines to be in device coordinates. An error is raised when the region specified is currently selected as the clip region.

This function can be hooked by the presentation driver.

Simulation support

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

Syntax

GreCombineShortLineRegion(hdc, hrgn, pScanData, pInstance, lFunction)

Parameters

hdc (HDC) - input

Device context handle.

hrgn (HRGN) - input

Region handle.

pScanData (PSCANDATA) - input

Pointer to a SCANDATA structure:

pslFirstLeft: Pointer to the left end of the first polyshortline

pslLastLeft: Pointer the left end of the last polyshortline

pslFirstRight: Pointer to right edge of first polyshortline

pslLastRight: Pointer to right edge of last polyshortline

c: Number of scan lines

rclBound: RECTL structure defining the bounding rectangle

slh: SHORTLINEHEADER structure:

ulStyle Line style

ulFormat Line format

ptlStart (x, y) position of start

ptlStop (x, y) position of end

lxLeft Left edge of bounding rectangle

lxRight Right edge of bounding rectangle

pslhNext Pointer to next shortline

pslhPrev Pointer to previous shortline

This structure is a discrete representation of a curve that starts at point (x0, y0) and ends at point (x1, y1). For each of the (y1-y0+1) rows, there is exactly one X value contained in the X array. The final point in the series is not drawn.

ax: Array of X values, as device coordinates.

pInstance (PVOID) - input

Pointer to instance data.

lFunction (ULONG) - input

High-order WORD=flags; low-order WORD=NGreCombineShortLineRegion.

Returns

rc (BOOL) - returns

This function returns BOOLEAN (fSuccess).

TRUE: Successful

FALSE: Error

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_HRGN
• 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         hrgn;       /*  Region handle. */
PSCANDATA    pScanData;  /*  Pointer to a SCANDATA structure: */
PVOID        pInstance;  /*  Pointer to instance data. */
ULONG        lFunction;  /*  High-order WORD=flags; low-order WORD=NGreCombineShortLineRegion. */
BOOL         rc;         /*  This function returns BOOLEAN (fSuccess). */

rc = GreCombineShortLineRegion(hdc, hrgn,
       pScanData, pInstance, lFunction);