- From: Andreas Tai <tai@irt.de>
- Date: Sun, 03 Nov 2013 19:27:10 +0100
- To: Glenn Adams <glenn@skynav.com>
- CC: public-tt <public-tt@w3.org>
- Message-ID: <5276957E.4020901@irt.de>
Apalogies if I did not made my intention clear enough. It was to prove that my interpretation is not correct and that the use of the feature is as defined in XSL:FO and CSS. My original interpretation of tts:overflow was always that it has the same semantics as in CSS. But in a conversation the part highlighted below was mentioned and I needed some clarification. In general I see it as a huge benefit that the layout and formatting of TTML is nearly fully compatible with CSS. This allows a smooth integration in web technologies like HTML 5. Thanks and best regards, Andreas Am 03.11.2013 07:10, schrieb Glenn Adams: > Basically, TTML is doing precisely what XSL-FO and CSS both do here, > as defined by the preliminary material in [1]. If you find yourself > interpreting TTML style properties in a way that is distinct from CSS > semantics, then you should question your interpretation first. We > never intentionally diverge except in noted extensions, particularly > the use of 'c' metric and the potential use of an anamorphic font size. > > [1] http://www.w3.org/TR/CSS2/visufx.html#overflow-clipping > > On Sat, Nov 2, 2013 at 12:00 PM, Andreas Tai <tai@irt.de > <mailto:tai@irt.de>> wrote: > > Thanks Glenn for the clarification! > > >> >> >> >From the TTML Spec: >> >> "If the value of this attribute is visible [...] region >> composition and layout must be performed as if the region's >> width and height were unconstrained" [1] >> >> >From my reading content that overflows the region extents >> the "box" of the region. >> >> >> No. It merely goes outside of that box (and is not clipped by it). >> >> That is different what is shown in the first example of >> tts:overflow where the background color is only applied to >> the contrained region extent. Only the text content is >> rendered outside of the regions box. >> >> >> The size of the box should not be changed for the purpose of >> drawing its background. > > OK. Seems that I misunderstood it. But from the conversation I had > with others I am not the only one. From my view the text marked in > red (and '*') leads to this misreading. From my view it would be > better to omit it (but possibly it is to late for a change). > > "If the value of this attribute is|visible|, then content should > not be clipped outside of the affected region*, and region > composition and layout must be performed as if the region's width > and height were unconstrained, but with a well-defined origin*. " > > > - Andreas > > > Am 01.11.2013 18:56, schrieb Glenn Adams: >> >> On Fri, Nov 1, 2013 at 10:30 AM, Andreas Tai <tai@irt.de >> <mailto:tai@irt.de>> wrote: >> >> I need some clarification regarding the tts:overflow [1] >> attribute in TTML 1.0 (2nd edition). >> >> 1) Is this attribute only an indicator how presentation >> processors should handle content that overflows a region? >> >> In the description of the desired presentation behaviour for >> "visible" and "hidden" the key word "should" and not "must" >> is used. >> (This seems to reflect the usage of overflow in XSL 1.1 and CSS) >> >> >> Yes. I suspect we used "should not be clipped" because other >> semantics outside the scope of interpreting this property may >> cause clipping. >> >> >> 2) Does tts:overflow "hidden" create a "dynamic sized region" >> where width and height adopts to the size of the content? >> >> >> No. It simply behaves as if the region into which this content is >> selected is unconstrained in width (or height) in the inline >> progression dimension. >> >> >> >From the TTML Spec: >> >> "If the value of this attribute is visible [...] region >> composition and layout must be performed as if the region's >> width and height were unconstrained" [1] >> >> >From my reading content that overflows the region extents >> the "box" of the region. >> >> >> No. It merely goes outside of that box (and is not clipped by it). >> >> That is different what is shown in the first example of >> tts:overflow where the background color is only applied to >> the contrained region extent. Only the text content is >> rendered outside of the regions box. >> >> >> The size of the box should not be changed for the purpose of >> drawing its background. >> >> >> Furthermore I believe that if the constrain is meant in that >> way it is not compatible with CSS. >> >> >> I'm not sure what you mean here. Could you be more precise, and >> provide an example (in both TTML and HTML/CSS)? >> >> >> - Andreas >> >> [1] http://www.w3.org/TR/ttaf1-dfxp/#style-attribute-overflow >> >> >> > > > -- > ------------------------------------------------ > Andreas Tai > Production Systems Television IRT - Institut fuer Rundfunktechnik GmbH > R&D Institute of ARD, ZDF, DRadio, ORF and SRG/SSR > Floriansmuehlstrasse 60, D-80939 Munich, Germany > > Phone:+49 89 32399-389 <tel:%2B49%2089%2032399-389> | Fax:+49 89 32399-200 <tel:%2B49%2089%2032399-200> > http:www.irt.de <http://www.irt.de> | Email:tai@irt.de <mailto:tai@irt.de> > ------------------------------------------------ > > registration court& managing director: > Munich Commercial, RegNo. B 5191 > Dr. Klaus Illgner-Fehns > ------------------------------------------------ > > -- ------------------------------------------------ Andreas Tai Production Systems Television IRT - Institut fuer Rundfunktechnik GmbH R&D Institute of ARD, ZDF, DRadio, ORF and SRG/SSR Floriansmuehlstrasse 60, D-80939 Munich, Germany Phone: +49 89 32399-389 | Fax: +49 89 32399-200 http: www.irt.de | Email: tai@irt.de ------------------------------------------------ registration court& managing director: Munich Commercial, RegNo. B 5191 Dr. Klaus Illgner-Fehns ------------------------------------------------
Received on Sunday, 3 November 2013 18:28:04 UTC