[cairo] Why 16bit coordinate space.

[Fabien Costantini]

Also, there is a chance that floating to fixed 24.8 conversion will be a bit faster than 22.10 because
the latest requires bit shifting and mask operations ...

----- Message d'origine ----
De : Bill Spitzak <spitzak at d2.com>
À : Carl Worth <cworth at cworth.org>
Cc : cairo at cairographics.org
Envoyé le : Lundi, 26 Juin 2006, 10h58mn 48s
Objet : Re: [cairo] Why 16bit coordinate space.

Google Fight:
Searches are for "fixed point 24.8", etc:

Format     Hits
24.8    1,090,000
22.10     260,000
20.12     265,000
18.14     148,000
16.16     197,000
14.18     185,000
12.20     349,000
10.22     554,000 (many uses of 10.22 as sample value)
  8.24     453,000

I would say that anything other than 24.8 is going to be a mistake due 
to the likelihood of hardware and/or library support.

Carl Worth wrote:

> Now, I don't think that anyone has ever argued that cairo really needs
> as many as 16 bits of sub-pixel positioning, so we could change that
> from 16.16 to something else. Where to put the dividing point? I know
> that fewer than 8 bits of sub-pixel precision would not be
> desirable. Is it enough? Maybe we would want something like 22.10 ?
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