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From "Graham Sanderson" <graham.sander...@lombardisoftware.com>
Subject RE: Custom elements and the "style" attribute
Date Wed, 12 Oct 2005 15:11:56 GMT
>From a literal reading of the two (though the CSS2 is a bit vague in the
unknown properties section), it seems that the two are not necessarily
contradictory:

a) CSSStyleDeclaration says all unknown properties must be exposed via
CSSStyleDeclaration
b) CSS2 states that illegal (not unknown) parts of the style sheet must
be ignored.
c) CSS2 states that to allow for future properties the user agent must
act as if the style had not contained the unknown attribute. Presumably
this implies that the unknown attribute must have no visible effect on
the user agent (in the absence of additional user script/java which
interprets the style settings). The question is, what effect would
adding a real style with the same name as some custom style later have
on the custom code; which seems like a lesser issue.

Of course my interpretation in c) could be entirely wrong, and the CSS2
may mean that the unknown declaration really must be ignored. In this
case (or the case in c) above) this certainly implies that the style is
not inherited. The question then becomes, should the CSSStyleDeclaration
interface perhaps allow you to get the "declared" properties instead.
Which is of course just a convenience method to parse the single element
level "style" attribute, and as such perhaps isn't super useful.

-----Original Message-----
From: Cameron McCormack [mailto:cam-batik-dev@aka.mcc.id.au] 
Sent: Wednesday, October 12, 2005 5:21 AM
To: batik-dev@xmlgraphics.apache.org
Subject: Re: Custom elements and the "style" attribute

Graham Sanderson:
> From the CSSStyleDeclaration documentation:
> 
>  
> 
> "While an implementation may not recognize all CSS properties within a
> CSS declaration block, it is expected to provide access to all
specified
> properties in the style sheet through the CSSStyleDeclaration
> interface."

That's interesting, since CSS 2 states[1]:

  In some cases, user agents must ignore part of an illegal style sheet.
  This specification defines ignore to mean that the user agent parses
  the illegal part (in order to find its beginning and end), but
  otherwise acts as if it had not been there.

  To ensure that new properties and new values for existing properties
  can be added in the future, user agents are required to obey the
  following rules when they encounter the following scenarios:

      * Unknown properties. User agents must ignore a declaration with
        an unknown property. For example, if the style sheet is:

            H1 { color: red; rotation: 70minutes }

        the user agent will treat this as if the style sheet had been

	    H1 { color: red }

This seems to contradict what's said in DOM 2 Style.  Certainly Batik's
CSS engine currently doesn't store any non-SVG CSS properties at the
moment.

Cameron

[1] http://www.w3.org/TR/CSS2/syndata.html#parsing-errors

-- 
  e-mail : cam (at) mcc.id.au    	icq : 26955922
     web : http://mcc.id.au/	        msn : cam-msn (at) aka.mcc.id.au
  office : +61399055779		     jabber : heycam (at) jabber.org

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