Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!wuarchive!zaphod.mps.ohio-state.edu!mips!sgi!shinobu!fido.wpd.sgi.com!marktwain.rad.sgi.com!linton
From: linton@marktwain.rad.sgi.com (Mark Linton)
Newsgroups: comp.windows.interviews
Subject: Re: GetCanvas returns NULL
Message-ID: <1991May14.220623.19750@fido.wpd.sgi.com>
Date: 14 May 91 22:06:23 GMT
References: <9105120300.AA29103@shiva.trl.OZ.AU> <1991May13.161932.28060@fido.wpd.sgi.com> <1991May14.052613.29659@bellcore.bellcore.com>
Sender: news@fido.wpd.sgi.com (Usenet News Admin)
Reply-To: linton@marktwain.rad.sgi.com (Mark Linton)
Organization: sgi
Lines: 16

In article <1991May14.052613.29659@bellcore.bellcore.com>, doron@mobydick.leis.bellcore.com (Doron Shalmon) writes:
|> Is there some point in the life of an interactor when it is guaranteed
|> to be mapped?  What I'm looking for is some member function in which
|> I can be guaranteed that the canvas is not nil (much the same way as
|> you *know* that the interactor knows about its parents and the world
|> in Reconfig).
|> 
|> Specifically, I have a damage object that needs to know the canvas
|> of a graphic block, and I'd like to have the graphic block take care
|> of this when it gets mapped (rather than do some explicit Set call
|> after I insert the graphic block into the world).

Resize is called when an interactor has a canvas.  However, there
is no corresponding call when a canvas is unmapped or removed.
Your damage object is therefore better off with a pointer to the graphic block and
calling GetCanvas on it.