Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!usc!zaphod.mps.ohio-state.edu!uwm.edu!psuvax1!psuvm!cxt105
From: CXT105@psuvm.psu.edu (Christopher Tate)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Emergeny help on picture drawing wanted!!!
Message-ID: <91029.212938CXT105@psuvm.psu.edu>
Date: 30 Jan 91 02:29:38 GMT
References: <1991Jan29.194323.7665@cs.umu.se>
Organization: Penn State University
Lines: 22

You need to call SetClip() before you construct the picture, otherwise
the problem you mention might happen:  you won't get any drawing at all
when you try to use DrawPicture() later on.

Initially, the clip region for the picture is set to the default,
arbitrarily large (or at least *very* large) rectangle.  Following
the call to OpenPicture(), you need to call SetClip() (or ClipRect()
or whatever is most appropriate) to reduce the clipping region to
something more managable.  Using the bounding rectangle of the PICT
is a good way to go.

I don't know why DrawPicture() behaves this way, but unless you set
the clipping region to be small, the picture won't produce output.
This is documented in Inside Macintosh Volume I, in the QuickDraw
chapter, in the section on OpenPicture() and DrawPicture().

-------
Christopher Tate                  |  I hate writing, and I hate statistics,
                                  |  but most of all I hate writing about
cxt105@psuvm.psu.edu              |  statistics.  I'd rather go to the
 ...!psuvax1!psuvm.bitnet!cxt105  |  dentist; at least there you get to spit.
cxt105@psuvm.bitnet               |                      - Ed Sewell