- From: Craig Northway <craign@cisra.canon.com.au>
- Date: Tue, 26 Apr 2005 15:45:51 +1000
- To: Bjoern Hoehrmann <derhoermi@gmx.net>
- Cc: www-svg@w3.org, WG SVG <w3c-svg-wg@w3.org>
Hi Bjoern, Bjoern Hoehrmann wrote: >Dear Scalable Vector Graphics Working Group, > > In http://www.w3.org/TR/2005/WD-SVGMobile12-20050413/struct.html the >playbackOrder attribute seems ill-designed. The default attribute is >defined as "all" which requires implementations to assume that seeking >backwards is possible even when there is evidence in the document that >this is unreasonable (mutation events are a good indicator). > > Please >change the draft such that the default value for the attribute is a new >value like "auto" which allows implementations to behave in a more >reasonable manner.. > The author is able to use the 'playbackOrder' feature when they create documents that are not designed to be rewound (seeking backwards). For instance heavily scripted content such as most web apps, games etc... should probably set playbackOrder to forwardOnly. Some complex long running animations may allow the user to 'rewind', seek backwards and play content again, hence playbackOrder will be unspecified or 'all'. Other complex animations may use the 'discard' element to reduce the memory required by the UA, these presentations are designed to play in the forward direction only, hence the indication to the user agent by specifying 'forwardOnly' that disables controls allowing backwards navigation of the timeline. The 'all' value indicates that no specific restrictions are placed on document timeline seeking. This is the same behaviour found in SVG 1.1. Are you suggesting a new 'auto' value that allows the UA to determine whether to allow seeking backwards? If this is what you mean, I think this is probably not a good idea. Or are you suggesting the current 'all' value (default behaviour from SVG 1.1 no restrictions) should be renamed 'auto'? >The draft further states "Similarly the UA should disable any controls >it may provide in the UI for seeking backwards." > Yes, we think the UA should do this if playbackOrder = "forwardOnly". What is the problem with this statement? > Please change the draft >to include a note that implementations may offer facilities to allow >effectively reloading the document fragment which is unaffected by this >attribute. > > Yes, I agree that the specification should clarify that the document can be reloaded regardless of the value for playbackOrder. Regards, Craig
Received on Tuesday, 26 April 2005 05:45:56 UTC