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From: klee@wsl.dec.com (Ken Lee)
Newsgroups: comp.windows.x
Subject: Re: XFillRectangles X Protocol error in R3
Message-ID: <1990Aug28.175614.4903@wrl.dec.com>
Date: 28 Aug 90 17:56:14 GMT
References: <9008272045.AA06156@pi3.local>
Sender: news@wrl.dec.com (News)
Reply-To: klee@wsl.dec.com
Organization: DEC Western Software Laboratory
Lines: 28


In article <9008272045.AA06156@pi3.local>, blakec@pi3.local (Carl D. Blake)
writes:
|> I have been using XFillRectangles to draw up to approximately 20,000
|> rectangles and have been getting the following X Protocol error:
|> 
|> X Protocol error:  BadLength poly request too large or internal Xlib length
error
|> Major opcode of failed request: 70 (X_PolyFillRectangle)
|> Minor opcode of failed request: 0

According to the X protocol, servers must accept protocol requests of
at least 16K bytes.  PolyFillRectangle is 8 bytes per rectangle plus 12
bytes of header, so you can send about 2000 rectangles with any
implementation.  Some implementations have higher limits.  Some Xlib
implementations, especially those based on the X11R4 sample Xlib, break
up the PolyFillRectangle requests to pieces within the 16K limit; with
these Xlib's, XFillRectangles calls can send many more rectangles
without worrying about the limit.

The same problem exists for other variable-length protocol requests.
Again, some Xlib's try to break up the long requests, but this is too
complicated for some requests, like FillPoly.

Ken Lee
DEC Western Software Laboratory, Palo Alto, Calif.
Internet: klee@wsl.dec.com
uucp: uunet!decwrl!klee