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RE: 3 questions: path syntax, path lengths, and animation syntax

From: Barend Köbben <kobben@itc.nl>
Date: Fri, 30 Dec 2005 16:53:15 +0100
Message-ID: <36141C39871E4D4DAE92F79D18385436017647E0@itcnt14.itc.nl>
To: <www-svg@w3.org>

Hi Patrick,
re. 1. and 2. I'll let others have their (more informed) say...
On the anmimate element the obvious advantage of having it as a child element to the rect (or whatever) is that you can have several child elements each doing their thing:
    <animate id=1 animates x from 10 to 100 in 30 seconds and ends then>
    <animate id=2 animates fillcolour from red to green every second and repeating>
    <animate id=3 animates rotation from 0 to 360 degrees verey 2 seconds>
Try putting that in your kind of syntax and uit quickly becomes unreadable...!
Barend Köbben 
International Institute for Geo-information Sciences and  Earth Observation (ITC) 
PO Box 6, 7500AA Enschede (The Netherlands) 
ph: +31-(0)534874253; fax: +31-(0)534874335 


From: www-svg-request@w3.org on behalf of Patrick Doyle
Sent: Wed 28.12.2005 18:34
To: www-svg@w3.org
Subject: 3 questions: path syntax, path lengths, and animation syntax


I have some questions for those of you in the know.  I'm sure these
issues have been addressed already on this list, but I had a look in
the archives and had a hard time finding anything that addressed these
issues specifically.

I'd appreciate it if anyone could point me toward answers for these questions...

1. Paths

It seems unfortunate that paths are not specified in XML, but rather
in a mini-language contained in the "d" attribute.  I fear that makes
them unavailable to the DOM, so (for instance) XSLT could not
translate paths.  The justification given is file size, but that seems
a poor reason to subvert the XML language.  Those concerned with file
size can use compression; surely, these days, any device capable of
processing SVG can also handle at least zip compression?

2. Path lengths

The effects of path length specifications seem somewhat ill-defined,
but I may have simply misunderstood.  The wording of section 8.4 seems
to imply that the user agent is entitled to presume that the path
length specified in an SVG file will be similar to the one computed by
the user agent, with the former more precise than the latter.  Why not
let the author specify any length he wants?  Why have the user agent
compute path lengths at all?  (Unless, of course, they are not
specified in the file.)

3. Animation

The "animate" elements seem inelegant to me.  I was hoping animation
would be accomplished by some syntax like <rect x="(t lt 10)?t:10"
y="3" width="4" height="5">, with an expression for the x value in
terms of time t in seconds.  This particular expressions says that
when t is less than 10, x=t, and afterward, x=10.  (Ok, this may not
be the ideal syntax, but you get the idea.)  Was this kind of approach
considered?  Do the "animate" elements have an advantage over this

Patrick Doyle
Received on Saturday, 31 December 2005 07:47:33 UTC

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