Inside Macintosh: Imaging With QuickDraw /

Chapter 3 - QuickDraw Drawing / QuickDraw Drawing Reference

Routines / Creating and Managing Regions

RectRgn

To change the structure of an existing region to that of a rectangle, you can use the RectRgn procedure.

PROCEDURE RectRgn (rgn:†RgnHandle; r:†Rect);

rgn

A handle to the region to restructure as a rectangle.

r

The rectangle structure to use.

DESCRIPTION

The RectRgn procedure destroys the previous structure of the SetRectRgn procedure, and it then sets the new structure to a rectangle that you specify in the r parameter.

As an alternative to the RectRgn procedure, you can use the SetRectRgn procedure, which accepts as parameters four coordinates instead of a rectangle.

SPECIAL CONSIDERATIONS

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