Calculates the difference between the union and the intersection of two regions.

void XorRgn (
     srcRgnA, 
     srcRgnB, 
     dstRgn
);

srcRgnA

A handle to the first of two regions to compare.

srcRgnB

A handle to the second of two regions to compare.

dstRgn

On return, a handle to the region holding the result.

This does not create the destination region; you must have already allocated memory for it by using the NewRgn function.

If the regions are coincident, XorRgn sets the destination region to the empty region defined by the rectangle (0,0,0,0).

DISCUSSION

The XorRgn procedure calculates the difference between the union and the intersection of the regions whose handles you pass in the srcRgnA and srcRgnB parameters and places the result in the region whose handle you pass in the dstRgn parameter.

This does not create the destination region; you must have already allocated memory for it by using the NewRgn function.

If the regions are coincident, XorRgn sets the destination region to the empty region defined by the rectangle (0,0,0,0).

SPECIAL CONSIDERATIONS

The XorRgn function may temporarily use heap space that’s twice the size of the two input regions.

The XorRgn function may move or purge memory blocks in the application heap; do not call this function at interrupt time.

AVAILABILITY

Supported in Carbon. Available in CarbonLib 1.0 and later when InterfaceLib 7.1 or later is installed. Exported by CarbonLib 1.0 and later and by InterfaceLib 7.1 and later.

© 2000 Apple Computer, Inc. — (Last Updated 4/14/2000)