[Rd] X11 help please

Peter Dalgaard p.dalgaard at biostat.ku.dk
Tue Jun 19 08:51:45 CEST 2007

Duncan Murdoch wrote:
> Duncan Murdoch wrote:
>> The rgl package currently crashes R when running under Xvfb (the 
>> "virtual frame buffer" server), at least on MacOSX.  It makes sense that 
>> it shouldn't be able to work there (it needs interactivity), but I don't 
>> know how to detect the problems before they cause the crash.
>> Currently the error happens the first time you try to open an rgl 
>> window; when rgl calls XCreateWindow R crashes with the error message
>> X Error of failed request:  BadMatch (invalid parameter attributes)
>>   Major opcode of failed request:  1 (X_CreateWindow)
>>   Serial number of failed request:  28
>>   Current serial number in output stream:  29
>> I've checked and as far as I can see all the parameters we're sending to 
>> XCreateWindow are valid, but I might have missed something:  I don't 
>> know much about X11 programming.  (The call is
>>   ::Window xwindow = XCreateWindow(
>>     xdisplay, RootWindow(xdisplay, DefaultScreen(xdisplay)),
>>     0, 0, 256, 256, 0,
>>     xvisualinfo->depth,
>>     InputOutput,
>>     xvisualinfo->visual,
>>     valuemask,
>>     &attrib
>>   );
>> but without context that's probably not worth much to others.)
Just a hunch: Is it possible that "attrib" contains uninitialized 
variables or is getting overwritten with random data?

>> Are there any experienced X11 programmers out there who can suggest what 
>> to do next?
> I have now committed some changes to rgl to avoid the crash -- it 
> converts the above error into an R error.
> I think to actually fix it, I'd need to debug the MacOSX Xvfb code to 
> see exactly what it's complaining about.  I don't know where to find 
> that source, so this isn't likely to happen soon.
> Are there any X11/MacOSX programmers going to the UseR! meeting in 
> August?  I'd guess if I could sit down with someone who had experience 
> with both of those we could track this down fairly quickly, but I don't 
> think I'll be able to do it without that.
> Duncan Murdoch
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