[Qgis-developer] QGIS+NX [was: X11 crash and clipping code]

[Maciej Sieczka]

Gary Sherman pisze:
> Has anybody made changes to the clipping code found in 
> src/core/qgsclipper.* ?
> 
> This issue (URL below) has a remarkable resemblance to the X11 bug that 
> we were plagued with until clipping was instituted:
> 
> https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/208899

Hi Gary

As nobody replies I thought it won't hurt if I add my 0.02 USD, though 
maybe not strictly related.

Using QGIS via NX (FreeNX) I have reproducible session shutdowns. They 
happen only with QGIS and only with particular vector data, that consist 
of many polygons with numerous vertices (eg. like raster to vector output).

I asked about the possible culprit on FreeNX ML [1] to not much avail, 
but by the way I learned that a similar issue has already been reported 
to NoMachine co. few months ago [2]. They have recently fixed the issue 
[3], though the fix has not yet been released by NoMachine nor FreeNX AFAIK.

My problem with QGIS & FreeNX in detail:

1. Establish an NX connection in *MODEM/ISDN/ADSL or WAN* mode (LAN mode 
will not expose the problem).
2. Start QGIS on the server.
3. Settings > Options > Rendering > Fix problems with incorectly filled
polygons
4. Load a specific shapefile into QGIS, like this one [4] (1.6MB).
5. The NX session shuts down when rendering in QGIS starts.

I can reconnect soon after, but redrawing the particular shapefile makes 
the session shut down again.

I'm using the "Fix problems with incorectly filled
polygons" becuase otherwise various display artifacts happen when using 
QGIS via NX: invisible polygon of the measure area tool, invisible line 
of the measure length tool, the backdrop map gets erased in the vicinity 
of vertex being currently dragged when digitizing etc. However with "Fix 
problems with incorectly filled polygons" I don't have crashes with any 
vector data, in any NX connection mode. It seems NX and QGIS don't like 
each other.

I wonder if my NX problems and the X server crash you mention might have 
something in common.

I will soon check how the sample dataset mentioned on the Launchpad 
interacts with NX+QGIS.

[1]http://www.nabble.com/forum/ViewPost.jtp?post=15863273&framed=y
[2]http://www.nomachine.com/tr/view.php?id=TR12E01973
[3]http://www.nomachine.com/tr/view_notes.php?commid=145&id=TR12E01973
[4]http://www.biol.uni.wroc.pl/sieczka/udostepnione/vmap0.tar.bz2 (1.6MB)

Maciek