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GreGetClipBox

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GreGetClipBox determines the dimensions of the tightest rectangle around the DC region in world coordinates. The DC region is defined as the intersection of the visible region, clip region, viewing limits, graphics field, and clip path. The bounding rectangle is inclusive. Points on its boundary are deemed to be inside it. If COM_TRANSFORM is not set, the rectangle points are returned in screen coordinates.

This function can be hooked by the presentation driver.

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

Syntax

GreGetClipBox(hdc, prclRect, pInstance, lFunction);

Parameters

hdc (HDC) - input
Device context handle.
prclRect (PRECTL) - input
Pointer to rectangle in world or screen coordinates.
RECTL structure:
xLeft Minimum x-coordinate of rectangle
yBottom Minimum y-coordinate
xRight Maximum x-coordinate of rectangle
yTop Maximum y-coordinate
The prclRect parameter is a NULL rectangle when the value of xRight is less than xLeft, and yTop is less than yBottom.
pInstance (PVOID) - input
Pointer to instance data.
lFunction (ULONG) - input
High-order WORD=flags; low-order WORD=NGreGetClipBox.

Returns

rc (LONG) - returns
Return codes.
This function returns an integer (lComplexity) indicating the complexity of the resultant "clipping region", which is defined as the intersection of all clipping (that is, the clip path, viewing limits, graphics field, clip region, and visible 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_INV_COORD_SPACE
  • 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

#define INCL_GRE_CLIP
#include <os2.h>

HDC       hdc;        /*  Device context handle. */
PRECTL    prclRect;   /*  Pointer to rectangle in world or screen coordinates. */
PVOID     pInstance;  /*  Pointer to instance data. */
ULONG     lFunction;  /*  High-order WORD=flags; low-order WORD=NGreGetClipBox. */
LONG      rc;         /*  Return codes. */

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