RE: ISSUE-257: Interpretation of percentage tts:fontSize on root (tt) element

Also, ditto for metadata attributes I think.

 

And re xml.xsd, see: http://www.w3.org/AudioVideo/TT/tracker/actions/60 

 

From: Michael Dolan [mailto:mdolan@newtbt.com] 
Sent: Tuesday, July 16, 2013 5:43 PM
To: 'public-tt'
Subject: RE: ISSUE-257: Interpretation of percentage tts:fontSize on root (tt) element

 

Agreed.  The new XML schema currently permits style attributes, and should be corrected.

 

Unrelated, but also about the schema, I thought we had found the authoritative xml.xsd on ww3.org a while back and we were going to defer to that and not include our own copy?

 

                Mike

 

From: Glenn Adams [mailto:glenn@skynav.com] 
Sent: Tuesday, July 16, 2013 4:49 PM
To: public-tt
Subject: Re: ISSUE-257: Interpretation of percentage tts:fontSize on root (tt) element

 

I was reviewing the recently closed ISSUE-257 today, and after further consideration, have determined it was incorrect, and needed to be reverted which I have done in [1].

 

The basic problem with the previous resolution is that TT Style Attributes are not defined for use on the tt element (with the exception of the special case of tts:extent). Furthermore, the outermost Content element [2] used during content style inheritance is the body element.

 

Ultimately, there is no element on which tts:fontSize can be specified that doesn't have a parent element. In the case of body, if no tts:fontSize is specified, then region style inheritance comes into effect. So that leaves us with a tts:fontSize potentially specified on region as the outermost inheritable font size. Accordingly, if the region's font size is specified in percentage, then we do need to resolve it against something other than its parent, since no ancestor of region participates in style inheritance.

 

I will now re-implement a fix for this issue based on the need to resolve percentage on region. 

 

[1] https://dvcs.w3.org/hg/ttml/rev/0355e9473d7e

[2] https://dvcs.w3.org/hg/ttml/raw-file/default/ttml10/spec/ttaf1-dfxp.html#element-vocab-type-content