[cairo] Why 16bit coordinate space.

Vladimir Vukicevic vladimirv at gmail.com
Mon Jun 26 10:57:12 PDT 2006


On 6/26/06, Paul Giblock <drfaygo at gmail.com> wrote:
> > Would 6 more bits be enough for your application?
>
> 22.10 _would_ be enough for my application. 2M is quite an increase
> from 32K.  I imagine that someone would still run into this problem
> for very large scrollable areas (ie. web pages).  However, this is
> where the userlevel hack can be applied by translating the area and
> then subtracting from the coordinates being drawn.

As long as there's a limit, you'll always have to write code that does
the translation anyway, especially if the user can add an arbitrary
data to whatever display you're using.  16.16 is only a problem if you
have a device that can display more than 32k x 32k pixels at a time,
but I think it will be a while before we get there -- and we can
always increase this to 24.8 or even start using 64-bit integers at
that point.

Otherwise, I'd suggest that this be handled via documentation -- just
describe what the limitation is, and that it only applies to
transformed coordinates.  Translating to some x,y base and then just
rendering everything with that x,y offset shouldn't be all that
complex to deal with.

   - Vlad


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