W3C home > Mailing lists > Public > www-svg@w3.org > April 2010

Is implied lineto after moveto ambiguous?

From: Rick <graham.rick@gmail.com>
Date: Wed, 21 Apr 2010 13:18:52 -0400
Message-ID: <l2u18569e001004211018kdd3ed2cawb7782df3715bab27@mail.gmail.com>
To: www-svg <www-svg@w3.org>
Hello Working Group.

In packing path data for a high traffic web feature, I came across
what I think is an ambiguity in the spec:

The definition for the moveto command (
http://www.w3.org/TR/SVG/paths.html#PathDataMovetoCommands ) in path
is as follows:

--
Start a new sub-path at the given (x,y) coordinate. M (uppercase)
indicates that absolute coordinates will follow; m (lowercase)
indicates that relative coordinates will follow. If a relative moveto
(m) appears as the first element of the path, then it is treated as a
pair of absolute coordinates. If a moveto is followed by multiple
pairs of coordinates, the subsequent pairs are treated as implicit
lineto commands.
--

Lineto comes in two flavours, but no mention is made in the
definition, or in the implementation notes (
http://www.w3.org/TR/SVG/implnote.html#PathElementImplementationNotes
), as to which lineto is implied.

It would seem to me that a relative move should imply a relative
lineto and an absolute move would imply an absolute lineto.

Further to this, if a path starts with a relative move, it is seen as
an absolute move, since there is nothing for it to be relative to, but
it could/should be used to imply a relative lineto.

I haven't tested browsers, I would be willing to expend the effort if
any interest is shown.

-- 
Cheers!
Rick
Received on Wednesday, 21 April 2010 17:19:24 GMT

This archive was generated by hypermail 2.3.1 : Friday, 8 March 2013 15:54:44 GMT