GreGetPel

GreGetPel returns the color of a pel at a specified position.

This function must be supported by the presentation driver, and is called by GpiQueryPel. GreGetPel is used to query the value of a pel at a specified (X,Y) coordinate within the DC. This function can be handled by bit-map simulation.

Simulation support: None. This function is mandatory for all drivers.

Syntax

GreGetPel(hdc, pptlPel, pInstance, lFunction);

Parameters

hdc (HDC) - input: Device context handle.

pptlPel (PPOINTL) - input: Pointer to the coordinate (X, Y) pair structure.

pInstance (PVOID) - input: Pointer to instance data.

lFunction (ULONG) - input: High-order WORD=flags; low-order WORD=NGreGetPel.

Returns

rc (LONG) - returns

Return Code.

This function must return the color index value for the pel, or CLR_NOINDEX if there is no index corresponding to the color. In addition, the handling routine must raise an error when the point is subject to any clipping.

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_BITMAP_NOT_SELECTED
PMERR_COORDINATE_OVERFLOW
PMERR_DEV_FUNC_NOT_INSTALLED
PMERR_HDC_BUSY
PMERR_INV_COORD_SPACE
PMERR_INV_COORDINATE
PMERR_INV_HDC
PMERR_INV_LENGTH_OR_COUNT
PMERR_INV_RECT
PMERR_PEL_IS_CLIPPED
PMERR_PEL_NOT_AVAILABLE

Refer to the "Error Explanations" section in the Presentation Manager Programming Reference for further explanation.

Sample

#define INCL_GRE_BITMAPS
#include <os2.h>

HDC        hdc;        /*  Device context handle. */
PPOINTL    pptlPel;    /*  Pointer to the coordinate (X, Y) pair structure. */
PVOID      pInstance;  /*  Pointer to instance data. */
ULONG      lFunction;  /*  High-order WORD=flags; low-order WORD=NGreGetPel. */
LONG       rc;         /*  Return Code. */

rc = GreGetPel(hdc, pptlPel, pInstance, lFunction);

Remarks

If COM_TRANSFORM is set, this position is in world coordinates. If not set, the position is in screen coordinates. The return value of this function is either the color index of the pel or its RGB value depending on the color mode of the device.