[cairo] Floating point API in Pixman

Dov Grobgeld dov.grobgeld at gmail.com
Wed Aug 11 06:16:20 PDT 2010

I'm sure that there are many others beside me who would like to have
inkscape working on ARM tables without having to resort to floating point
emulation libraries for cairo, as that will probably slow down inkscape
quite a lot. (But I'm just guessing.) Thus, an integer solution, might be
preferable for performance reasons. (At least optionally).


On Wed, Aug 11, 2010 at 11:50, Jean-Claude Repetto <jcrml at mxm.eu> wrote:

> Le 11/08/2010 08:00, M Joonas Pihlaja a écrit :
>> On Wed, 11 Aug 2010, Soeren Sandmann wrote:
>>  For the matrix in pixman_image_t, I think we need to just move to
>>> single precision floating point unconditionally. There are several
>>> cases where 16.16 fixed point simply doesn't have enough either range
>>> or precision.
>> [snip]
>> Before deciding on the kind of floating point, could we think very
>> hard about the precision and accuracy guarantees pixman would like to
>> make for each of its operations?  Single precision floating point is
>> not very far off from 16.16 after all, so I worry that we'll be in the
>> same boat very quickly again if we're not careful.
>> Joonas
> Please don't forget that Cairo is used on some processors that don't have
> FPU (such as ARM processors). So if you introduce floating point, it MUST be
> optional.
> Jean-Claude
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