GpiPtVisible
This function checks whether a point is visible within the clipping region of the device associated with the specified presentation space.
Syntax
GpiPtVisible(hps, pptlPoint)
Parameters
- hps (HPS) - input
- Presentation-space handle.
- pptlPoint (PPOINTL) - input
- Point to be checked.
- The point is given in world coordinates.
Return Value
- lVisibility (LONG) - returns
- Visibility indicator.
- PVIS_INVISIBLE - Not visible
- PVIS_VISIBLE - Visible
- PVIS_ERROR - Error.
Remarks
For the purposes of this function, the clipping region is defined as the intersection between the application clipping region, and any other clipping, including windowing.
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_COORDINATE (0x205B)
- An invalid coordinate value was specified.
Example Code
This example uses GpiPtVisible to check whether (150,150) is visible within the clipping region of the device associated with the presentation space.
#define INCL_GPIPRIMITIVES /* Primitive functions */
#include <os2.h>
LONG lVisibility; /* visibility indicator */
HPS hps; /* Presentation-space handle */
POINTL pptlPoint = {150L,150L};/* point to be checked */
lVisibility = GpiPtVisible(hps, &pptlPoint);