BadLength error. RE: [cairo] gtkcairo

Damian Dixon Damian.Dixon at
Fri Jan 5 00:00:00 PST 2007

Hi Ignas,


> The error was 'BadLength (poly request too large or internal Xlib
length erro'.


The problem is down to the X-Server buffers.


Run the program 'xdpyinfo' on the machine in question and post the
output to the cario list.


The output from one of my machines is (cut down):



name of display:    pooky:0.0

version number:    11.0

vendor string:    The Cygwin/X Project

vendor release number:    60899901

maximum request size:  16777212 bytes

motion buffer size:  256


The figure of interest is the 'maximum request size'.


The only way for this to be avoided is for polygons with large number of
points (and lines) to be split up in such away as to not exceed the
space available. This will probably need to be done in the xlib backend.
Though the user could also do this as well by clipping the offending
polygons to a line.


This is a problem I am getting with my own code (not cario) on Solaris
10 with the default installed X-Server. Lucky this does not happen with
our code too often as we filter out points when converting from user
space to device space. I will not be able to provide any pointers to a
solution for awhile though as I am currently stuck writing code for M$


The max' buffer size is only 262140 bytes! As shown below.


name of display:    pollux:0.0

version number:    11.0

vendor string:    Sun Microsystems, Inc.

vendor release number:    6620

maximum request size:  262140 bytes


Hopefully this provides some insight into the cause of the problem and a
couple of potential solutions.




Damian Dixon, BSc(Hons), BSc(Hons), FRGS.
TENET Technology Ltd., North Heath Lane, Horsham, West Sussex, RH12
5UX,United Kingdom
Tel: +44 1403 273173  Fax: +44 1403 273123
Email: damian.dixon at
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