Is there a defined xpixmap width limit?

[Emmanuel Thomas-Maurin]

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 at gmail.com>