TR : [Moderator Action] I need more explanation of the syncbase events

-----Message d'origine-----
De : Dana Rosenfeld [mailto:dana.rosenfeld@emblaze.com] 
Envoyé : mercredi 8 janvier 2003 16:42
À : www-smil@w3.org
Objet : [Moderator Action] I need more explanation of the syncbase
events



I'm resending this mail, since I can't see it on the mail archive.
--------------------------------------------------------------------
Hi,

I have a real difficulty understanding the difference between the
syncbase values and the event values.
In the W3C SMIL 2.0 specification (chapter 10.3.3, "Building the
instance times lists") there is a description of if and when resolved
event-values & resolved synchbase-values should be cleared from the
list. What I can't understand, is what happens to events when their
element restarts. 

Consider the next example:
   <par dur="10s">
	 <par dur="5s">
	         	<img id="img1" src="../images/frown.jpg"
dur="6s"/>
	 </par>
             <img id="img2" src="../images/smile.jpg" begin="0s;5s"
end="img1.end" dur="4s"
                  restart="whenNotActive" />
	<img id="img3" src="../images/captions_off.jpg" begin="img2.end"
dur="1s"/>
    </par>

It is obvious that img1.endEvent is raised at t=5s, and img1.end is
raised at t=6s.The begin & beginEvent will be raised at t=0s.

As for the second image (img2) - I presume that the beginEvent will be
raised at t=0s & at t=5s. The endEvent will be raised at t=4s and at
t=6s.
The problem I have is for the begin & end of img2. The first question is
when would img3 begin? on t=4s? on t=6s? both?
In this example img2 instance time lists are all resolved, but what if
it was written instead: begin="img1.activateEvent" ? When should I send
the "end" event? 

To be more clear, I would like to know when do "end" and "begin"
syncbase-events are raised. 

My assumption is, that "begin" is sent at the scheduled begin of the
element (even if it doesn't really starts playing due to parent time
container's constraints etc.) - once; "end" is sent when the element was
supposed to stop (and if it has a list of const begin list - the
calculated end is the end of the last interval) - also once.
The only exception is for user dependant event values - if the element
can also begin with an "activateEvent" and/or  "click" (and restart
semantics allow that) - the element would be restarted. If this restart
changes the computed end time (new end time is bigger than the older
one) - both "end" and "begin" events would be sent when the new interval
begins and another "end" event at the end of this last interval.

I hope you could answer my questions as soon as possible, since we would
like to release a SMIL engine version soon.

Regards,

Dana Rosenfeld


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Received on Wednesday, 8 January 2003 10:44:46 UTC