Possible X11 server bug

[Jon TURNEY]

On 05/09/2014 17:55, mathog wrote:
> I have run into an issue which _may_ indicate a bug in the cygwin X11
> server.  The issue is documented here:
>
>     https://bugs.launchpad.net/inkscape/+bug/1365153
>
> In brief, for certain test files viewed in Inkscape (current trunk at
> least) over a putty ssh tunnel from an Ubuntu 12.04lts system to the
> cygwin 1.14.1.0 X11 server there are glitches in the image when it is
> zoomed in and out.  This does not occur if the same program is run
> locally on the console of the test machine.

Thanks for reporting this problem.

It's not quite clear, but I think you are saying that it renders 
correctly when run locally on the Ubuntu 12.04 system?

There are a couple of possible variables, which might affect things

The version of the X server may not be the same.  It would be useful to 
compare the same version, and also be helpful if you could test with the 
most recent X server (1.16.0)

FWIW, the .svgs attached to that bug seem to render identically 
(although I'm not sure what correctly looks like) using a Cygwin 
Inkscape 0.48.4 r9939 (from cygwinports) and X server 1.16.0-1

> It also does not happen if
> I run a native Windows version (not cygwin, not X11) of Inkscape on the
> same PC which hosts that X11 server on the same test files.  The glitch
> does not occur with a huge number of other test files I have looked at
> over the years.  It seems there is something specific to the clipping
> code in Inkscape and this particular X11 transport path/server
> combination.  Moreover, it looks like the problem is only manifested (or
> only manifested frequently) when the clipping path consists of two (or
> more?) disjoint sections.
>
> When the glitches occur nothing is added to XWin.0.log.
>
> Also this X11 server is not running in the full cygwin environment, but
> rather in one edited down to just the minimum needed to run the X11
> server.  I distribute this version here:
>
>     http://sourceforge.net/projects/minimalcygwinx/
>
> I don't think this is a factor though, since all of the action is going
> on inside the X11 server process(es).

-- 
Jon TURNEY
Volunteer Cygwin/X X Server maintainer

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