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animate-elem-39-t timing issue

From: Cameron McCormack <cam@mcc.id.au>
Date: Wed, 22 Dec 2010 14:12:13 +1300
To: public-svg-wg@w3.org
Message-ID: <20101222011212.GD11105@wok.mcc.id.au>
I think animate-elem-39-t also suffers from a timing issue wrt
non-interpolable values.  The <animate> that targets the <a
xlink:href=“> is currently:

  <a xlink:href="animate-elem-09-t.svg">
    <animate attributeName="xlink:href"
      from="animate-elem-09-t.svg" to="animate-elem-03-t.svg"
      begin="1s;showAnchor2.end+1s" dur="1s"/>
  </a>

According to spec, an animation with calcMode="linear" will be treated
as calcMode="discrete" if the attribute is of a type that doesn’t have
values that can be interpolated.  A discrete from-to animation will show
the from value for the first half of the simple duration and the to
value for the second half.  Thus the link target is changed to
"animate-elem-03-t.svg" for a quarter of the time the document is
running:

  |------|------|FFFFFF|TTTTTT|------|---...
  0s     0.5s   1s     1.5s   2s     2.5s

where:

  “-” means the animation isn’t applied and the underlying value of
      the attribute is used ("animate-elem-09-t.svg")
  “F” means the animation is applied, and is applying the from value
      (also "animate-elem-09-t.svg")
  “T” means the animation is applied, and is applying the to value
      ("animate-elem-03-t.svg")

This doesn’t match up with the changes to the actual text being
displayed (the “09” or “03”).

What we instead want is either:

  |FFFFFF|FFFFFF|TTTTTT|TTTTTT|FFFFFF|FFF...
  0s     0.5s   1s     1.5s   2s     2.5s

or:

  |------|------|TTTTTT|TTTTTT|------|---...
  0s     0.5s   1s     1.5s   2s     2.5s

I propose that we change this animation to be like some of the others in
the document:

  <animate attributeName="xlink:href"
    from="animate-elem-09-t.svg" to="animate-elem-03-t.svg"
    begin="0s;showAnchor2.end" dur="2s"/>

Let me know if you agree (anyone).  I will make this change unless there
are any objections.

-- 
Cameron McCormack ≝ http://mcc.id.au/
Received on Wednesday, 22 December 2010 01:12:51 GMT

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