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Re: SURVEY: Accept requirement for immediate mode graphics a la canvas element?

From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
Date: Fri, 30 Nov 2007 20:28:04 +0100
To: public-html@w3.org
Message-Id: <200711302028.04956.Dr.O.Hoffmann@gmx.de>

Dave Singer wrote:

> At 16:02  +0100 30/11/07, Dr. Olaf Hoffmann wrote:
> >I think, this part of the working draft would be more convincing, if there
> > was an element like animation (as in SMIL, SVG Tiny 1.2 or vector or
> > however one might call it) to reference vector graphics too (optionally
> > with server-sided generation to avoid user-sided scripting) - either as
> > an external file similar to audio or video or to embed it in a mixed
> > document XHTML+SVG as a clear separation...
> FWIW the 'animation' element in SVG has a definition problem.  Unlike
> video, audio, or image, which talk about a media type with
> characteristics, where the actual format is defined by the MIME type
> of the thing embedded, the animation element refers directly to SVG.

This is currently a restriction for SVG tiny 1.2, in SMIL it is in general
for 'Animated vector graphics or other animated format'

> Further, it's not clear to me what the media-type difference is from
> video or audio:  a timed presentation, possibly with indefinite
> duration or fixed duration, possibly with visual appearance, and
> possibly with user interaction.  These are all true of <video>;  what
> extra semantics does <animation> bring (apart from the unfortunate
> restriction above)?

I did not look into detail of this scripted raster image, because I do not
use scripting, but isn't this argument applicable for the canvas content too?
If it is a script, the script element would be already pretty
good. If it is a (raster) image, the img element would be sufficient, if it
can be timed the video element would be fine too. And if it is timed
and can be interactive, an animation element could replace it too.  

However then all of them need a more precise definition. Why not
to use the src attribute on canvas to refer to an SVG of another
graphical object, replacing maybe the img? Could be used too for
SMIL or flash in a similar approach.
video typically is not interactive and frame based, ok maybe there
are some more advanced formats, but this is typical for videos
I have seen yet. Normally the controls are outside and not inside the
video and a video has typically a simple time structure (frame based),
while in SMIL or SVG animations any animatable property or
attribute has its own timing. Therefore for a video it is typically
simple to extract somehow a simple media duration, for a SMIL
or SVG or flash it is not.
Is a flash-document more a video, an image or an animation?
What authors have to use for it or similar formats? I never used
it, but I think, it is frame based, timed, interactive, therefore a video?
What about animated GIF?
SMIL+XHTML - can be continuous, timed, interactive, looks like a video
too. SMIL itself? (X)HTML+CSS (+scripting) is typically interactive and
somehow time dependent too can be quite similar to SVG for some 
'designers' today - video format? image format?
From this point of view maybe the object can be renamed to video
or video, audio, canvas can be skipped and everything can be left
to object, because everything has some functionality in common.
But OK, if it is intended, that SVG should be referenced with the
video element or if mixed (SVG+XHTML), that the video element
is recommended to be used as a container for SVG - why not, if it
works in this case indeed - why not, canvas would be a better 
naming for it, maybe this should work too - why to be fussy, this is
the element with the best fitting name currently...

> At 17:43  +0100 30/11/07, Dr. Olaf Hoffmann wrote:
> >Thierry Michel referred already a nice comparsion to SMIL to this
> >list. Interestingly no one commented it yet...
> >Maybe if authors have the requirement to have access to timing
> >controls, it looks like a good idea to reference a SMIL or SVG tiny 1.2
> >document instead of using the video or audio elements.
> >I think, currently several use already flash for this purpose.
> actually, there is currently no standard or recommended way to
> reference SVG or SMIL from HTML.  The <audio> and <video> elements
> are intended for this exact purpose (among others).

Well, currently in HTML4 it is simply the object element, but see the
discussion above, canvas would be a nice wording too, just the prose 
has to be improved slightly to align the functionality to the name - 
canvas as an generic element for graphical content like animation, 
video, scripted images, static images, why not? 
Maybe if canvas is defined as a generic container for grapical content, 
it is better acceptable too as something with really a functionality 
even without user sidede scripting. Currently for a markup language
it is only an empty container, hungry for some graphics.

The question about audio and video is more, why not to use
timing and some basic modules from SMIL instead of defining
this again in HTML5? Currently this looks like a more advanced
approach concerning accessibility and experience with multimedia.
Received on Friday, 30 November 2007 19:52:10 UTC

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