XorRgn

Find the union, less the intersection of two regions

#include <Quickdraw.h> Quickdraw

void XorRgn(srcRgnA, srcRgnB, destRgn );

RgnHandle srcRgnA ; the two existing . . .

RgnHandle srcRgnB ; . . . source regions

RgnHandle destRgn ; handle of region to hold result

XorRgn calculates the union of two regions, except for any portions that

overlap, and stores the result into a third region.

srcRgnA and . . .

srcRgnB are handles of existing regions in the current GrafPort.

destRgn is the handle of an existing region. Its current structure is

destroyed and it is given the structure defining a logical XOR of the

areas of srcRgnA and srcRgnB . It is OK if this parameter is the

same as either of the source regions.

Notes: The destRgn must already exist (see NewRgn). The difference between

the union and the intersection of srcRgnA and srcRgnB is calculated, and

the result is stored as destRgn :

srcRgnA srcRgnB destRgn

This is functionally equivalent to the following sequence:

RgnHandle uRgn, sRgn;

NewRgn( uRgn );

NewRgn( sRgn );

UnionRgn( srcRgnA, srcRgnB, uRgn );

SectRgn( srcRgnA, srcRgnB, sRgn );

DiffRgn( uRgn, sRgn, destRgn );

If srcRgnA is identical to srcRgnB , then destRgn is set to a region defined

by the empty rectangle (0,0)(0,0). You can test for this via EmptyRgn.

Referenced by (7):