Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!bloom-beacon!eru!luth!sunic!ifi!m2cs.uu.no!tomas
From: tomas@m2cs.uu.no (Tomas Felner)
Newsgroups: comp.windows.news
Subject: Re: Flickering canvases
Keywords: moving canvas flickering
Message-ID: <1989Nov9.071316.1617@m2cs.uu.no>
Date: 9 Nov 89 07:13:16 GMT
References: <1989Nov6.111754.11056@m2cs.uu.no> <1272@odin.SGI.COM>
Organization: Modula-2 CASE Systems A/S, Oslo, Norway
Lines: 36

msc@ramoth.esd.sgi.com (Mark Callow) writes:
>In article <1989Nov6.111754.11056@m2cs.uu.no>, tomas@m2cs.uu.no (Tomas
>Felner) writes:
>> I have a problem with moving canvases that has been bothering me for
>> quite some time. The basic situation is as follows: I have a canvas
>> ontop of which I have another canvas, on top of which another one, etc. I
>> have code to grab one of those canvases with the mouse and move them around.
>> All the canvases on top of the grabbed canvas are then moved together
>> with the grabbed one. When moving this "stack of canvases" the moving of 
>> the bottommost canvas goes smoothly, but all the canvases on top of it
>> flicker like crazy! This effect appears with any stack of canvases and 
>> with an arbitray number of canvases on top of the bottom canvas.

>You don't say what version of NeWS you are running...

Sorry, it's NeWS 1.1 on a Sun 3/50.

>In NeWS 1.1 (and 4Sight) when you move a canvas containing opaque children,
>the opaque children are unmapped while the canvas is moved then remapped. 
>This may be the cause of your flickering.  The unmapping was done to ensure
>that some obscure case involving retained canvases and save unders would
>work correctly.  I believe Sun found this to be unnecessary so NeWS 2.0
>(X11/NeWS) doesn't unmap the canvases anymore. 

Is there any way to avoid this mapping/unmapping under NeWS 1.1 or does
anyone have a good solution for this. I haven't ported my stuff to
X11/NeWS yet, but if it works there, I guess I have to look into it (I
have to do it anyway sooner or later).

Tomas
-- 
                          Tomas Felner
     Modula-2 CASE Systems AS  |  Internet: tomas@m2cs.uu.no
            Maridalsveien 139  |  Phone: +47 2 379784
        N-0461 Oslo 4, Norway  |  FAX: +47 2 356448