GpiPolyLine
This function draws a series of straight lines starting at the current position and connecting the points specified.
Syntax
GpiPolyLine(hps, lCount, aptlPoints)
Parameters
- hps (HPS) - input
- Presentation-space handle.
- lCount (LONG) - input
- Number of points.
- Must not be negative. Zero is valid but causes no output.
- aptlPoints (PPOINTL) - input
- Array of points.
Return Value
- lHits (LONG) - returns
- Correlation and error indicators.
- GPI_OK
- Successful
- GPI_HITS
- Correlate hits
- GPI_ERROR
- Error.
Remarks
On completion, current position is set to the last point. The maximum number of lines allowed in a polyline is device dependent, but is always greater than 3 500 for GPIF_LONG format spaces and always greater than 7 200 for GPIF_SHORT format spaces (see the PS_FORMAT of GpiCreatePS for the meaning of this format).
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_LENGTH_OR_COUNT (0x2092)
- An invalid length or count parameter was specified.
- PMERR_INV_COORDINATE (0x205B)
- An invalid coordinate value was specified.
- PMERR_INV_NESTED_FIGURES (0x20A8)
- Nested figures have been detected within a path definition.
Graphic Elements and Orders
- Element Type
- OCODE_GCLINE
Note that GpiLine also generates this element type.
Order: Line at Current Position
As many of these orders are generated as is necessary to hold the specified points.
Example Code
#define INCL_GPIPRIMITIVES /* Or use INCL_GPI, INCL_PM, Also in COMMON section */ #include <os2.h> HPS hps; /* Presentation-space handle. */ LONG lCount; /* Number of points. */ PPOINTL aptlPoints; /* Array of points. */ LONG lHits; /* Correlation and error indicators. */ lHits = GpiPolyLine(hps, lCount, aptlPoints);
This example uses the GpiPolyLine function to draw a triangle.
#define INCL_GPIPRIMITIVES /* GPI primitive functions */
#include <os2.h>
HPS hps; /* presentation space handle*/
POINTL ptlTriangle[] = { 100, 100, 200, 0, 0, 0 }; /* vertices */
GpiMove(hps, &ptlTriangle[2]); /* moves to end point (0, 0)*/
GpiPolyLine(hps, 3L, ptlTriangle); /* draws triangle */