2013-10-23 10:24:41: Created issue 'Extend the background area behind rendered text to improve readability' nickname rowPadding owned by Nigel Megitt on product TTML2, description 'The current rendering rules for TTML allow for a background colour to be specified, to be painted behind rendered text. However the edges of this background area are coincident with the foreground text boundary, or with the entire region, neither of which meets all use cases. A common practice in rendering subtitles against video is to extend slightly the background area painted behind the foreground text, e.g. by the width of one space character .
No proposed solution is available to address the general case of this, which has some complexity e.g. what to do if a <span> has a different background colour from its parent <p> and the text in the span is wrapped over a line. However the specific use case can be addressed either by specifying a generic rendering rule to cover all text in a region or even a document, e.g. a tts:rowPadding attribute with a length value. Alternative proposals for indicating the requirement for presentation processors to use this rendering behaviour are welcomed!
' non-public [Nigel Megitt]