Legacy Document

Inside Macintosh: Imaging With QuickDraw /

Chapter 3 - QuickDraw Drawing / QuickDraw Drawing Reference

Routines / Managing the Graphics Pen

HidePen

To give the graphics pen invisible ink (which means that pen drawing doesn't show on the screen), use the HidePen procedure.

PROCEDURE HidePen; 

DESCRIPTION

The HidePen procedure decrements the pnVis field of the current graphics port. The pnVis field is initialized to 0 by the OpenPort procedure. Whenever pnVis is negative, the pen doesn't draw on the screen. The pnVis field keeps track of the number of times the pen has been hidden to compensate for nested calls to the HidePen and ShowPen routines.

Every call to HidePen should be balanced by a subsequent call to ShowPen, which is described next.

The HidePen procedure is called by the OpenRgn, OpenPicture, and OpenPoly routines so that you can create regions, pictures, and polygons without drawing on the screen.