[Xquartz-dev] X Error

[George Peter Staplin]

Quoted nico <sl1200mk2 at gmail.com>:

> hi,
> first of all, many thanks for your great job !!
>
> i had this error :
> X Error of failed request : BadIDChoice (invalid resource ID chosen for
> this connection)
> Major opcode of failed request: 148 (RENDER)
> Minor opcode of failed request: 4 (RenderCreatePicture)
> Resource id in failed request: 0xa876d1
> Serial number of failed request: 2704569
> Current serial number in output stream: 2704572
>
> this error happens sometimes, with no particular reason, and that's a
> very bad point!!!
> it lead my app to close immediately.
> i'm using XQuartz with TK.
> this error happened with 2.3.2.1 and 2.3.3 rc3
>
> can you please have a look to this and guide me to find the bug because
> i don't know wich one of my C code, or TK or XQuartz is faulty....
>
> best regards
> nico
> __________________________

Hi Nico,

I believe I may have seen this error before in the context of Tk.  I'm  
a Tk maintainer/developer on SourceForge.

Are you trying to draw text with something like Tk_DrawChars?  Be  
aware that Tk for X11 will fail if you try to draw to a 1-bit deep  
Pixmap.  This is a regression in Tk that occurred in 8.5, when the  
libXft-based text rendering was added.  libXft IIRC uses Render.  I  
wrote a patch for this issue that solved the problem for some users  
that used BLT and other extensions, but the other Tk developers  
thought the fix was too costly, and believed it would harm network Tk  
performance.  Unfortunately there isn't a better way of solving the  
problem, and it certainly hasn't been solved by the other developers,  
so if this is the problem, you should use a deeper Pixmap, or  
--disable-xft.

An easy way to confirm if the problem is caused by what I suspect it  
is, is to configure Tk with --disable-xft.

This is from the tk/unix/README:
  --disable-xft           Disable support for antialiased fonts via the
                                 Freetype/xft library. By default, this is
                                 switched on whenever the configure script can
                                 detect the required libraries.

If the problem goes away, then look for pixmaps with limited depth,  
and try to use 8 or more as a depth.

The patch I seem to have deleted, but it basically worked by using a  
different libXft function for 1-bit deep pixmaps, based on the  
XGetGeometry depth result for a drawable.  The unfortunate problem was  
that there wasn't a way of exposing or caching the depth, because XIDs  
(used for Pixmap identifiers) are reused after destruction, and there  
wasn't enough information passed to the text drawing code. The XC-MISC  
extension provides the reuse of XIDs to clients automatically.  It  
used to be that X11 didn't reuse XIDs (before XC-MISC was added as an  
extension), and apps that ran a long time would eventually exhaust all  
space, but for the last 10-15 years that hasn't been so.


George
-- 
http://people.freedesktop.org/~gstaplin/