GrePtVisible

GrePtVisible checks whether a point is visible within the DC region of the specified device context. The "DC region" is defined as the intersection of the application clipping and the window clipping.

This function can be hooked by the presentation driver.


 * Simulation support: This function is simulated by a handling routine in the graphics engine.

Syntax
GrePtVisible(hdc, pptlPoint, pInstance, lFunction);

Parameters

 * hdc (HDC) - input
 * Device context handle.


 * pptlPoint (PPOINTL) - input
 * Pointer to (X,Y) point in world or screen coordinates.


 * If COM_TRANSFORM is not set, the function expects the point to be in screen coordinates.


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


 * lFunction (ULONG) - input
 * High-order WORD=flags; low-order WORD=NGrePtVisible.

Return Code

 * rc (LONG) - returns
 * Return codes.


 * This function returns an integer (lVisible) indicating the visibility of the point:


 * PVIS_ERROR Error
 * PVIS_INVISIBLE Not visible
 * PVIS_VISIBLE Visible


 * 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_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


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

Sample Code

 * 1) define INCL_GRE_CLIP
 * 2) include 

HDC       hdc;        /*  Device context handle. */ PPOINTL   pptlPoint;  /*  Pointer to (X,Y) point in world or screen coordinates. */ PVOID     pInstance;  /*  Pointer to instance data. */ ULONG     lFunction;  /*  High-order WORD=flags; low-order WORD=NGrePtVisible. */ LONG      rc;         /*  Return codes. */

rc = GrePtVisible(hdc, pptlPoint, pInstance, lFunction);

