Article View: comp.windows.interviews
Article #1137Re: GetCanvas returns NULL
From: Mark Linton
Date: Mon, 13 May 1991 16:19
Date: Mon, 13 May 1991 16:19
21 lines
1232 bytes
1232 bytes
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.
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<1991May13.161932.28060@fido.wpd.sgi.com>Path:
arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!mips!sgi!shinobu!fido.wpd.sgi.com!marktwain.rad.sgi.com!lintonReferences:
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!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: <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