[cairo] Floating point API in Pixman

Jean-Claude Repetto jcrml at mxm.eu
Wed Aug 11 01:50:47 PDT 2010

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.


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