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List:       freedesktop-xorg
Subject:    Re: Is there a defined xpixmap width limit?
From:       Emmanuel Thomas-Maurin <manutm007 () gmail ! com>
Date:       2011-04-22 16:58:06
Message-ID: 4DB1B39E.8000806 () gmail ! com
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On 04/22/2011 06:39 PM, Marty Jack wrote:
> 
> 
> On 04/22/2011 11:44 AM, Emmanuel Thomas-Maurin wrote:
> > On 04/22/2011 04:48 PM, Michael Stapelberg wrote:
> > > Hi Emmanuel,
> > > 
> > > Excerpts from Emmanuel Thomas-Maurin's message of 2011-04-22 14:31:04 +0200:
> > > > I've been searching for this for a while: Is there a width and height
> > > > limit for xpixmaps? I'm using GTK and I know GDK pixmaps and windows
> > > > can't be wider than 65535. And I suspect for X, it's 32767.
> > > As the width/height fields in the CreatePixmap request are CARD16s, the highest
> > > value is (2^16)-1 = 65535. This is documented in the X protocol, see
> > > http://www.x.org/releases/X11R7.6/doc/xproto/x11protocol.pdf (page 56 in the
> > > pdf).
> > > 
> > > Best regards,
> > > Michael
> > 
> > Thanks Michael, that's what I was looking for. Maybe the results I got
> > from the test come from some specific implementation that's not 100 %
> > fully compliant with the protocol but that's really not that important
> > anyways.
> > 
> > Best regards,
> > Manu
> > 
> 
> Despite the fact that CARD16 is unsigned, in practice widths and heights are \
> limited to the signed range, up to 32767. 
> Here is an old paper by some of the original implementors that discusses the \
> problems with mixing signed and unsigned in the protocol. 
> www.std.org/~msm/common/WhyX.pdf

Thanks for the clarification. It would be much better if GDK could use
the same limit so I will probably file a GDK-bug.

-- 
Emmanuel Thomas-Maurin <manutm007@gmail.com>
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