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getPresentationTrait needs clarifications

From: Nicolas Pierre <nicolas.pierre@streamezzo.com>
Date: Mon, 28 Aug 2006 17:40:11 +0200
Message-ID: <8FEC5B98BD05584C9DBA4EF7116BB3116399EE@rennes.streamezzo.lan>
To: <www-svg@w3.org>

Hello SVG Working Group,

During our implementation we had some questions about
getPresentationTrait. I think that some clarifications should to be
added to avoid interoperatibility issues.

1. Should a presentation value be computed more than once within the
same frame ? Is it a compliant viewer if it performs only one
computation per frame ?
Consider the following scene part :
<g id="myg" fill="red">
   <rect id="myrect" fill="inherit" ...>
      <animateColor from="inherit" to="black" attributeName="fill" ..../>
   </rect>
</g>

And this script :
r = document.getElementById("myrect"); 
g = document.getElementById("myg"); 
v1 = myrect.getPresentationTrait("fill");
g.setAttributeNS(null, "fill", "blue");
v2 = myrect.getPresentationTrait("fill");

v1 is a color between red and black according to the animateColor state.
To compute v1 inheritance and animation interpolation need to be
performed.
If the expected value for v2 is a color between blue and black the
presentation value must be recomputed.
Is it the conformant behavior ?

2. Presentation value for an element within a defs.
Consider this content :
<svg ...>
   <defs>
      <g>
         <rect id="r1" fill="inherit">
            <animateColor from="inherit" to="black" attributeName="fill"
..../>
         </rect>
      </g>
   </defs>
   <rect id="r2" ...>
      <handler type="application/ecmascript" ev:event="click">
         r = document.getElementById("r1");
         v = r1.getPresentationTrait("fill");
      </handler> 
</svg>

What is the expected value returned by the getPresentationTrait since r1
is never rendered?
Similarly, are presentation values available even if the element is
excluded from the rendering tree (display='none') ?

3. Presentation value availability when load event is fired.
Consider this content :
<svg ...>
   <rect id="myrect" fill="red">
      <handler type="application/ecmascript" ev:event="load">
         r = document.getElementById("myrect");
         v = r1.getPresentationTrait("fill");
      </handler> 
      <set to="black" attributeName="fill" begin="0"/>
   </rect>
</svg>

I think the retrieved presentation value depends on the value of
svg.timelineBegin attribute. Is it correct ?
If svg.timelineBegin = onLoad what is the presentation value since the
document timeline is not initialized ?

Thanks in advance.
Received on Tuesday, 29 August 2006 13:40:31 GMT

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