- From: Helder Magalhães <helder.magalhaes@gmail.com>
- Date: Thu, 26 Jun 2008 12:17:43 +0100
- To: "Dr. Olaf Hoffmann" <Dr.O.Hoffmann@gmx.de>
- Cc: www-svg@w3.org
> I think, the missing arc commands are more related to a tiny profile than to > version 1.2, because they are not available in SVG tiny 1.1 too: > http://www.w3.org/TR/SVGMobile/#sec-shapes Agreed. :-) > As many other shapes elliptical arcs cannot be exactly expressed with > cubic curves. > Depending on the accuracy requirements, an author can compute > a set of cubic curve fragments to replace an elliptical arc approximately. > Typically a good approach is to demand that position and derivates fit > together at the end of cubic curve fragments joined together to an > approximation of an elliptical arc. > How many curve fragments are needed to get the desired > accuracy obviously depends on the requirements of the author, > therefore there cannot be a general rule to do this approximation. > However, the rule described above is an even more general > rule how to approximate any continuously differentiable curve > with a cubic curve, but this needs some calculations, either analytical > or numerical. Sounds well. I'd challenge you to marsh up these suggestions into a cleaner writing (possibly with already referred arc implementation notes [1] look) and posting them here (or in a separate thread), potentially accompanied by relevant illustrations. This would allow the WG to more easily pick this up and (possibly) add to a (new?) specification annex, labeled "SVG Full to Tiny content migration" or equivalent. :-) > I needed for some reasons already a cubic curve replacement > for an ellipse, circle and some other shapes like spirals, atomic > transition dipole moment shapes, therefore I already did this with > a small PHP script analytically or numerically and it is not really > a big issue if one is familiar with basic analytics. Could you share it? Reinventing the wheel is not one of those tasks anyone wants to deal with - if this would be publicly made available, it would probably help many to prepare for SVG Tiny content. ;-) As a side note: how about creating a "SVG Full to SVG Tiny path data converter" tool? It would parse the path data and replace the arc commands with your PHP script output. Of course a general "SVG Full to SVG Tiny" content converter would be even more interesting, which could then warned about possible content conversion limitations. I wonder if I'm also proposing a wheel reinvention and such tool is already available...? :-D Best regards, Helder Magalhães [1] http://www.w3.org/TR/SVG11/implnote.html#ArcImplementationNotes
Received on Thursday, 26 June 2008 11:18:19 UTC