RE: [opendocument-users] svg:d issues

[J David Eisenberg <catcode@catcode.com>]

On Fri, 20 Jan 2006, Jon Ferraiolo wrote:

> (SVG expert speaking up)
> 
> I don't understand "no mixtures of open and closed curves for one
> shape". SVG path data is built on a notion of subpaths, where each
> subpath begins with a "moveto" command (for pen plotter fans, lift the
> pen up). Perhaps this wording means that ODF only supports a single
> subpath within its path data.
> 
> Regardless of what the above quoted phrase was intended to convey, it
> goes against interoperability goals to include optional features.
> 
> I agree that elliptical arcs can be approximated easily via cubic
> beziers, but I also think it is reasonable to exclude them. One the Full
> profile of SVG supports elliptical arcs; the Tiny and Basic profiles do
> not. (http://www.w3.org/TR/SVGMobile/#sec-shapes)
> 

I've never understood why this is reasonable.  Unless someone has an easy
formula for doing these approximations, simple pie charts become a
horrible task. And no, I don't consider the formulas in 
http://www.spaceroots.org/documents/ellipse/elliptical-arc.pdf to be 
trivial. I can't believe that nobody uses arcs in ordinary drawings.
Furthermore, the corners on rounded rectangles are described in terms of
an ellipse, so the support for drawing these arcs must be there already.

-- 
J. David Eisenberg  http://catcode.com/