- From: Sjoerd Mullender <sjoerd@acm.org>
- Date: Wed, 27 Jun 2007 13:01:57 +0200
- To: www-smil@w3.org
- CC: Cyril Concolato <cyril.concolato@enst.fr>, Bjoern Hoehrmann <derhoermi@gmx.net>, Cameron McCormack <cam-www-smil@aka.mcc.id.au>, Patrick Schmitz <cogit@ludicrum.org>
- Message-ID: <468243A5.6050604@acm.org>
Several people have reported in the past that there is a contradiction in SMIL 2.0 (and 2.1) Animation with respect to the CSS OM. I am now trying to address this issue, but I would like to get some feedback. But first my apologies that this took so long. Until recently there was nobody within the Working Group really responsible for Animation. I am now trying to resolve these old issues in preparation for the next version of SMIL. The problem, as I understand it, is that in the Sandwich Model we say: - the value on which the animation is to operate is read from the CSS OM using getComputedStyle(); - the new, computed value is written to the override style sheet in the CSS OM. The problem with this is that getComputedStyle() (apparently -- I am not a CSS expert) takes the override style sheet into account, and thus there is at the very least confusion, and quite possibly a contradiction, with the possible result that animations are applied more than once. This is of course not the intention. SMIL Animations should be applied once, so we should fix the text to make that clear(er). Of course, we should keep in mind that the relevant text is all only informative. The current text says: "When animation is applied to CSS properties of a particular element, the base value to be animated is read using the (readonly) getComputedStyle() method on that element. The values produced by the animation are written into an override stylesheet for that element, which may be obtained using the getOverrideStyle() method." My proposal is to tack a sentence on to this: "Note that it is assumed that before reading the value, the override stylesheet is cleared so that the animation works on the original document value." My question to the various reporters (and others): would this be sufficient to resolve the issue? Links: The relevant bit in the latest public Working Draft of SMIL 3.0: http://www.w3.org/TR/2006/WD-SMIL3-20061220/smil-animation.html#animationNS-AnimationSandwichModel The relevant bit in the current recommendation (SMIL 2.1): http://www.w3.org/TR/2005/REC-SMIL2-20051213/animation.html#animationNS-AnimationSandwichModel Messages in which the issue was reported: http://lists.w3.org/Archives/Public/www-smil/2005OctDec/0027 http://lists.w3.org/Archives/Public/www-smil/2006JanMar/0017 http://lists.w3.org/Archives/Public/www-smil/2006JulSep/0019 -- Sjoerd Mullender
Received on Wednesday, 27 June 2007 11:07:42 UTC