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Re: [svg-developers] <use> an external file

From: Thomas DeWeese <Thomas.DeWeese@Kodak.com>
Date: Wed, 07 Jan 2004 08:06:21 -0500
Message-ID: <3FFC044D.7090209@Kodak.com>
To: Jonathan Chetwynd <j.chetwynd@btinternet.com>
Cc: svg-developers@yahoogroups.com, www-svg@w3.org

Jonathan Chetwynd wrote:
> Dean,
> 
> Gifs, bitmaps, jpgs, png, MSvector are all external files, why is SVG 
> different?

     It isn't in SVG Tiny (aimed at cellphones) all these files
would have to be included 'inline' (data protocol).

> Is there another graphics format that isn't linked to externally?
> 
> Can we please have an explanation of what the particular issue is with 
> respect to SVG?

    Use (especially external use) is difficult to implement properly
because all the CSS stylesheets are the ones from the referenced
document but CSS property inheritance is "as though" the referenced
content is a child of the use element.

    Add to this the fact that modifying the referenced content must
update all use instances and you have a real nightmare to implement
(ASV 6.0 is the only implementation to get it right yet for dynamic).

    But I think this misses the point, from a spec perspective
use of external elements is required (except for tiny which doesn't
require support for any external resources).  It is the
implementations that are the problem here (now it might be argued
that SVG 1.0 should have made implementation easier but that is
a rather pointless argument to make today).

> Graphics do need to be portable, upgradeable and maintainable,
> Wherever the problem is it needs a serious rethink.
> 
> Having now completed the accessible site, all 5 pages, I can safely 
> state that this will not be happening again in a hurry.
> 
> thanks again
> 
> Jonathan
> On Tuesday, January 6, 2004, at 03:18 pm, Dean Jackson wrote:
> 
>     On Tue 06 Jan 2004, Jonathan Chetwynd wrote:
> 
>      > I would like to emphasise what a ridiculous hassle it is updating
>     and
>      > maintaining an SVG site where "<use> an external file" is not
>     available
>      > Being in the process of making our site
>      > _http://www.peepo.co.uk/launch/index.svg_ accessible on a variety of
>      > browsers.
>      >
>      > This would appear to be a relatively minor technical problem to
>     solve
> 
>     Unfortunately it is a very difficult technical problem :(
>     Probably one of the hardest bits of an SVG implementation (IMO).
> 
>      > and should be essential in all SVG standards including tiny and
>      > mobile....
> 
>     The lack of CSS in Tiny makes it a little easier to do external <use>,
>     but we try to avoid all external references in Tiny.
> 
>     Dean
> 
> 
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> <image.tiff>
> 
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> 
> Jonathan Chetwynd
> http://www.peepo.co.uk
> "A web by people with learning difficulties"
> 
Received on Wednesday, 7 January 2004 08:10:05 GMT

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