W3C home > Mailing lists > Public > www-svg@w3.org > May 2005

[SVGMobile12] Stroke processing model missing

From: Ian Hickson <ian@hixie.ch>
Date: Fri, 20 May 2005 13:01:41 +0000 (UTC)
To: www-svg@w3.org
Message-ID: <Pine.LNX.4.61.0505201206510.12543@dhalsim.dreamhost.com>


There does not appear to be a definition anywhere in the SVG 1.2 Tiny spec 
of how stroking is actually supposed to be rendered.

For example, I could not find a single conformance criteria relating to 
how the 'stroke-dashoffset' property is used. In fact, I could only find 
three conformance criteria in the entire section on stroke properties 
(section 11.4), namely:

  "In all cases, all stroking properties which are affected by 
  directionality [...] must be rendered such that the stroke operation 
  starts at the same point at which the graphics element starts."

  "For stroking properties such as dash patterns whose computations are 
  dependent on progress along the outline of the graphics element, 
  distance calculations are required to utilize the SVG user agent's 
  standard Distance along a path algorithms."

  "When stroking is performed using a complex paint server, such as a 
  gradient, the stroke operation must be identical to the result that 
  would have occurred if the geometric shape defined by the geometry of 
  the current graphics element and its associated stroking properties 
  were converted to an equivalent 'path'  element and then filled using 
  the given paint server."

The first of these seems meaningless -- I don't understand what it means 
to "render" a "stroking property". The second is an empty statement since 
the spec does not define any stroking property computations as far as I 
can tell. The third could be a definition of how stroking should work, I 
guess, except that it limits itself to "complex paint servers", which 
leaves the question of how to render solid strokes unanswered, and it 
relies on a geometry of the stroking properties, which is not defined.

Please define what the stroking processing model actually is, with strict 
testable conformance requirements.

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Friday, 20 May 2005 13:01:47 GMT

This archive was generated by hypermail 2.3.1 : Friday, 8 March 2013 15:54:30 GMT