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From: linton@marktwain.rad.sgi.com (Mark Linton)
Newsgroups: comp.windows.interviews
Subject: Re: GetCanvas returns NULL
Message-ID: <1991May13.161932.28060@fido.wpd.sgi.com>
Date: 13 May 91 16:19:32 GMT
References: <9105120300.AA29103@shiva.trl.OZ.AU>
Sender: news@fido.wpd.sgi.com (Usenet News Admin)
Reply-To: linton@marktwain.rad.sgi.com (Mark Linton)
Organization: sgi
Lines: 21

In article <9105120300.AA29103@shiva.trl.OZ.AU>, s.michnowicz@trl.oz.au (Simon Michnowicz - A Free Spirit) writes:
|> I have an application, which consists uses a painter to
|> display text.
|> 
|> i.e.
|> Redraw()
|>   {
|>   C=GetCanvas()
|>   P= new Painter;
|>   P->Text(...)
|>   }
|> 
|> THis works when I raise and lower the window.  I print
|> out the value of the pointers generated.
|> However when I call redraw explicitely, to update the
|> screen,  GetCanvas() returns a null pointer , and the
|> program crashes.

Please explain in what context you are calling redraw explicitly.
If you call redraw when the window is unmapped, for example,
the canvas will be nil.