## Presentation Device Driver Reference for OS/2

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### GreGetRegionRects - Parameters

hdc (HDC) - input Device context handle.

hrgn (HRGN) - input Region handle.

prclBoundRect (PRECTL) - input Pointer to bounding rectangle.

RECTL structure:

xLeft Minimum x-coordinate of window
yBottom Minimum y-coordinate
xRight Maximum x-coordinate of window
yTop Maximum y-coordinate

Only rectangles intersecting this bounding rectangle are returned. If this pointer is NULL, all rectangles in the region are enumerated. If this pointer is not NULL, only rectangles that intersect the bounding rectangle are returned. Each of these rectangles is the intersection of the bounding rectangle with a rectangle in the region.

pControl (PRGNRECT) - input This is a pointer to a RGNRECT structure:

lrcStart The rectangle number to start enumerating (1 indicates start at the beginning).

If parclRect is NULL, this field is always 1.

crc The number of rectangles that can fit into the buffer (at least 1).

If parclRect is NULL and the clip region is completely within prclBoundRect , crc contains the value RRGN_INSIDE.

If parclRect is NULL and the clip region is completely outside prclBoundRect, crc contains the value RRGN_OUTSIDE.

If parclRect is NULL and the clip region spans prclBoundRect, crc contains the value RRGN_PARTIAL.

crcReturned Number of rectangles that were written into the buffer. If less than lrcStart, there are no more rectangles to enumerate.

If parclRect is NULL and the clip region is completely within prclBoundRect , crcReturned contains the value 1.

If parclRect is NULL and the clip region is completely outside prclBoundRect, crcReturned contains the value 0.

If parclRect is NULL and the clip region spans prclBoundRect, crcReturned contains the number of clip rectangles.

usDirection The direction in which the rectangles are listed:

RECTDIR_LFRT_TOPBOT Left-to-right, top-to-bottom
RECTDIR_RTLF_TOPBOT Right-to-left, top-to-bottom
RECTDIR_LFRT_BOTTOP Left-to-right, bottom-to-top
RECTDIR_RTLF_BOTTOP Right-to-left, bottom-to-top

If parclRect is NULL, usDirection is not applicable.

parclRect (PRECTL) - input Pointer to array of rectangle structures that define the region.

pInstance (PVOID) - input Pointer to instance data.

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

rc (BOOL) - returns Return codes.

This function returns BOOLEAN (fSuccess).

TRUE Successful
FALSE Error

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_HRGN_BUSY
PMERR_INV_COORDINATE
PMERR_INV_HRGN
PMERR_INV_RECT
PMERR_INV_REGION_CONTROL
PMERR_REGION_IS_CLIP_REGION

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