Re: Padding on tt:p and tt:span elements

On Wed, Apr 25, 2012 at 5:22 AM, John Birch <John.Birch@screensystems.tv>wrote:

>  In TTML as I understand it(as a result of derivation from xsl:fo?),
> there is no possible mechanism that can *set* the region size as a result
> of a calculation of the *rendered* text size on the display. In contrast
> to broadcast practises, in TTML the text is fitted inside a predefined
> region (or overflows / clips), rather than the region (growing) fitting the
> text.
>

it can, if the size can be determined at authoring time; but that will
depend on font usage; so you are correct that if the font size is unknown,
then you may have to overestimate the size, e.g., by using em or c length
units