hdc (HDC) - input

Device context handle.

hrgn (HRGN) - input

Region handle.

prclRect (PRECTL) - input

Pointer to rectangle in device coordinates.

RECTL structure:

xLeft

Minimum x-coordinate of rectangle
yBottom
Minimum y-coordinate
xRight
Maximum x-coordinate of rectangle
yTop
Maximum y-coordinate
The rectangle passed is considered "exclusive" on the right and top sides. If the rectangle represents the bounding box of a graphic object to be drawn, the drawing might include the right and top sides. In this case, the caller should "inflate" the top and right sides by one unit in device-coordinate space.

pInstance (PVOID) - input

Pointer to instance data.

lFunction (ULONG) - input

High-order WORD=flags; low-order WORD=NGreRectInRegion.

rc (LONG) - returns

Return codes.

This function returns an integer (lInside) indicating whether the rectangle is inside the region:

RRGN_ERROR

Error
RRGN_INSIDE
All in region
RRGN_PARTIAL
Partially in region
RRGN_OUTSIDE
Not in region
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_REGION_IS_CLIP_REGION

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