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

Am 24.04.2012 16:23, schrieb Glenn Adams:
>
> On Tue, Apr 24, 2012 at 1:41 AM, Andreas Tai <tai@irt.de 
> <mailto:tai@irt.de>> wrote:
>
>     As in TTML a region has always a predefined size, tt:p- and
>     tt:span elements are the better choices to apply a non-transparent
>     background color on a subtitle block that dynamically grows and
>     shrinks with the corresponding text.
>
>
> I'm not sure I understand what you mean by "has always a predefined 
> size". If by this you mean the "same" size, then I would not agree. A 
> region's size (extent) can be changed at any time by using <tt:set>.

With "predefined" I wanted to express that the width and the height of 
the region are set before the text is rendered. The values are defined 
in a TTML document by a tts:extent attribute that applies to a region or 
(if no tts:extent attribute applies) by the default value "auto" which 
means that the region has the same width and height as the root container.

Maybe the timing semantic of "predefined" and "before" can be a bit 
misleading here. It is maybe more that the width and height of the 
region are independent of the size of the content that is flowed into 
the region.

Hope this makes it clearer.
>
>     Unfortunately padding cannot be applied to tt:p and tt:span
>     elements and the very common use case to have empty space between
>     text and the border of a centered "text box" with dynamic width is
>     hard to implement (for an illustration of two use cases see the
>     attached images).
>
>     Therefore the EBU-Working group that specifies the TTML subset
>     EBU-TT sees the requirements to add padding as an applicable style
>     property for the tt:p and tt:span elements.
>
>     Best regards,
>
>     Andreas
>


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Production Systems Television IRT - Institut fuer Rundfunktechnik GmbH
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