SMIL z-index requirement (was: Re: agenda item for w3m: CSS extension Note0

I guess the message I pointed you to is a bit confused, since
it doesn't give an exmaple where there's actually a problem.

Here is one, using CSS syntax:

>    <smil>
>      <head>
>        <style>
>	[region="c1"] { position: absolute; top: 5px; left: 5px }
>	[region="c2"] { position: absolute; z-index: 6; top: 5px; left: 5px }
>        </style>
>      </head>
>      <body>
>	<img region="c1" ... />
>	  <anchor z-index="7" coords="0,0,0,0" />
>	</img>
>	<img region="c2" src="img.gif" />
>      </body>
>    </smil>

>      _________________                 global context   local context
>     /                /
>    /________________/  anchor                 7               none ?
>      _________________
>     /                /
>    /________________/  image "c2"             6               none ?
>      _________________
>     /                /
>    /________________/  image "c1"          auto               none ?

On 15/12/1998, Bert Bos <Bert.Bos@sophia.inria.fr>  wrote:

>- The regions are all in the same "sub-space" and thus are stacked
>  simply according to the value of their z-index. The default for
>  z-index is '0' (there is no 'auto' in SMIL, luckily. I wish it
>  hadn't existed in CSS either...).

this would indeed solve the problem above, since every element
would define a local stacking context

but where in SMIL is it specified that the default is "0" ? ah, i 
see, in the DTD, and also in the "rendering" note
although the text says:
"The use and definition of this attribute are identical to the "z-index" 
property in the CSS2 specification"

and i'm pretty sure that my intention was that the default value for z-index
would be the same as in CSS, i.e. auto.

On the other hand, I seem to have explicitly changed the default value
of top and left from "auto" to "0" - otherwise the text in the SMIL
rec wouldn't mention this.

so let's assume this is not an editing error :-)

So the solution/answer to the request from SYMM would be:
 
"Just define a different default value than CSS2 (i.e. 0 instead of audio). 
Btw, you're already doing this. Then you can add a local z-index attribute
to the anchor element 
You would have to add an additional rule to your 'default stylesheet',
namely

* {z-index:0}

and while you're at it, also add the following missing rules

* {top:0}
* {left:0}

"

Do you have a way to make this an official response of the WG
to this requirement raised in the Note ?

Am i right in assuming that this would not make rendering a SMIL
document with a CSS2 based renderer more difficult ?

...

Received on Thursday, 17 December 1998 19:26:48 UTC