Legacy Document

Inside Macintosh: Imaging With QuickDraw /

Chapter 3 - QuickDraw Drawing / QuickDraw Drawing Reference

Routines / Creating and Managing Regions

SetEmptyRgn

To set an existing region to be empty, use the SetEmptyRgn procedure.

PROCEDURE SetEmptyRgn (rgn:\xDDRgnHandle);

rgn

A handle to the region to be made empty.

DESCRIPTION

The SetEmptyRgn procedure destroys the previous structure of the region whose handle you pass in the rgn parameter; it then sets the new structure to the empty region defined by the rectangle (0,0,0,0).

SPECIAL CONSIDERATIONS

The SetEmptyRgn procedure may move or purge memory blocks in the application heap. Your application should not call this procedure at interrupt time.