UnionRgn

Calculate the combined area of two regions

#include <Quickdraw.h> Quickdraw

void UnionRgn(srcRgnA, srcRgnB, destRgn );

RgnHandle srcRgnA ; the two existing . . .

RgnHandle srcRgnB ; . . . source regions

RgnHandle destRgn ; handle of region to hold result

UnionRgn calculates the union of two regions (the combined area of both)

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 the union 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 union of srcRgnA and

srcRgnB is calculated, and the result is stored as destRgn :

srcRgnA srcRgnB destRgn

If both regions are empty, destRgn is set to a region defined by the empty

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

Referenced by (11):