Determines whether a rectangle intersects a region.

Boolean RectInRgn (
    const Rect *r, 
     rgn
);

Parameter descriptions

r

The rectangle to check for intersection.

rgn

A handle to the region to check.

function result

TRUE if the rectangle specified in the r parameter intersects the region whose handle is specified in the rgn parameter. The RectInRgn function returns TRUE if the intersection encloses at least 1 bit or FALSE if it does not.

DISCUSSION

If the points or rectangles supplied to this function are defined in a graphics port other than your current graphics port, you must convert them to the local coordinate system of your current graphics port. You can accomplish this by using the SetPort function to change to the graphics port containing the points or rectangles, using the LocalGlobal function to convert their locations to global coordinates, using SetPort to return to your starting graphics port, and then using the GlobalToLocal function to convert the locations of points or rectangles to the local coordinates of your current graphics port.

SPECIAL CONSIDERATIONS

The RectInRgn function sometimes returns TRUE when the rectangle merely intersects the region’s bounding rectangle. If you need to know exactly whether a given rectangle intersects the actual region, use RectRgn to set the rectangle to a region, and call SectRgn to see whether the two regions intersect. If the result of SectRgn is an empty region, then the rectangle does not intersect the region.

AVAILABILITY

Supported in Carbon. Available in Carbon 1.0.2 and later when running Mac OS 8.1 or later.

© 2000 Apple Computer, Inc. (Last Updated 6/30/2000)