Legacy Document

Inside Macintosh: Imaging With QuickDraw /

Chapter 3 - QuickDraw Drawing / QuickDraw Drawing Reference

Routines / Creating and Managing Regions

NewRgn

To begin creating a new region, use the NewRgn function.

FUNCTION NewRgn: RgnHandle;

DESCRIPTION

The NewRgn function allocates space for a new, variable-size region; initializes it to the empty region defined by the rectangle (0,0,0,0); and returns a handle to the new region. This is the only function that creates a new region; other routines merely alter the size or shape of existing regions.

To begin defining a region, use the OpenRgn procedure, described next.

SPECIAL CONSIDERATIONS

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

Use the Memory Manager function MaxMem (described in Inside Macintosh: Memory) to determine whether the memory for the region is valid before using NewRgn.

SEE ALSO

Listing 3-8 on page 3-24 and Listing 3-9 on page 3-25 illustrate how to use this function.