GreIntersectClipRectangle

GreIntersectClipRectangle sets the new clipping region to the intersection of the current clip region and the specified rectangle.

This function is supported by the graphics engine and can be hooked by the presentation driver.

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

Syntax

GreIntersectClipRectangle(hdc, prclRect, pInstance, lFunction);

Parameters

hdc (HDC) - input: Device context handle.

prclRect (PRECTL) - input: Pointer to rectangle (RECTL structure) in world or device coordinates:

xLeft Minimum x-coordinate of rectangle
yBottom Minimum y-coordinate
xRight Maximum x-coordinate of rectangle
yTop Maximum y-coordinate All the boundaries of the rectangle are inclusive (part of the interior) and are not clipped. If COM_TRANSFORM is not set, the function expects the rectangle to be in device coordinates.

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

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

Return Code

rc (LONG) - returns: Return codes.

This function returns an integer (lComplexity) indicating the complexity of the DC region:

RGN_ERROR Error
RGN_NULL Null region
RGN_RECT Rectangular region
RGN_COMPLEX Complex region (more than 1 rectangle)

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_INSUFFICIENT_MEMORY
PMERR_INV_COORD_SPACE
PMERR_INV_COORDINATE
PMERR_INV_HDC
PMERR_INV_HRGN
PMERR_INV_IN_AREA
PMERR_INV_IN_PATH
PMERR_INV_LENGTH_OR_COUNT
PMERR_INV_RECT
PMERR_INV_REGION_CONTROL

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

Remarks

When no clip region exists, GreIntersectClipRectangle must create one. The application must then free the handle when it subsequently selects another clip region. The return value of this function is the complexity of the resultant DC region, which is defined as the intersection of all clipping.

Sample Code

#define INCL_GRE_CLIP
#include <os2.h>

HDC       hdc;        /*  Device context handle. */
PRECTL    prclRect;   /*  Pointer to rectangle (RECTL structure) in world or device coordinates: */
PVOID     pInstance;  /*  Pointer to instance data. */
ULONG     lFunction;  /*  High-order WORD=flags; low-order WORD=NGreIntersectClipRectangle. */
LONG      rc;         /*  Return codes. */

rc = GreIntersectClipRectangle(hdc, prclRect,
       pInstance, lFunction);