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

Received on Tuesday, 16 July 2013 23:49:23 UTC