Hi Victor,
One of aXSL's other potential client applications has suggested that points
(represented by floats) be used instead of millipoints for parameters and
return values in the font system. I thought I had seen something on fop-dev
recently that made me think that a similar move was being considered for
other parts of FOP, but I may have dreamed it.
Related issues have been raised here:
http://marc.theaimsgroup.com/?l=fop-dev&m=112538394431613&w=2
I have never felt strongly about the matter either way. aXSL is till
malleable enough to bend to such a change, and FOray will go along. If such
a move is a benefit to FOP, all other known interested parties will be OK
with it also, and I will handle the work on the aXSL and FOray sides. If it
is *not* a benefit to FOP, IMO that kills the matter and aXSL will continue
to use millipoints and other parties can convert as needed. I mention the
whole thing only as an opportunity.
The task of converting FOP may be non-trivial, so I wouldn't assume that
Vincent has signed up for that as part of his current work.
I'm personally in favor of the best technical solution. In a first look I would
tend to think that floats are better suited as they are potentially more precise
than integers representing millipoints. In millipoints usual values will be
comprised between 0 and 5,000,000 (2m paper sheet), that is only a part of the
integer range. With integers it isn't possible to represent values inferior to 1
millipoint, whereas it is possible with floats. That could result in less
rounding errors.
That said, millipoint already is a very small length unit. Rounding errors at
the millipoint level may not be perceptible. Let's imagine we cumulate an error
as much as 0.5 mpt on a 2m paper sheet, we end up with a less than 3 pt error.
Of course if we multiply rounded values the error might grow up.
To conclude, I'm not sure if it will be a great benefit to switch to float
values. I don't know how the values are manipulated and which are the
requirements of the renderers. I'm asking for others' opinions.
Of course the switching won't simplify my work, but I'm not obliged to do it
right now. I'm working on snapshots of aXSL and FOray and I'm not required to
update them. I could to the conversion after a primary version is integrated
into the trunk.
Vincent
