RE: [FONTS] Embedding in ODF -- Existing Provisions

["Dennis E. Hamilton" <de...@acm.org>]

Here is the *technical* opening for font embedding in the ODF specifications.

In ODF 1.2 CS01 Part 1, sections 19.910.29 <svg:definition-src> xhtml:href attribute and  19.910.30 <svg:font-face-uri> xhtml:href attribute.  These can be relative references to internal parts of the package, of course.  That is how embedding can be done.  MIME types are needed (in META-INF/manifest.xml) for the  referenced parts.  The MIME type is what discriminate what kind of font-material is there.

Element <svg:font-face-uri> (15.24) is a none-or-more alternative child of <svg:font-face-src>.

Element <svg:font-face-src> (16.22) is an optional child of <style:font-face>.

Element <svg:definition-src> (16.25) is an optional child of <style:font-face>.

The gold is 16.21 <style:font-face>.  This only appears as a child of <office:font-face-decls> (section 13.4).

This structure has existed since ODF 1.0, so it already appears in ISO/IEC IS 26300:2006, in ODF 1.1, the forthcoming IS 26300 alignment with ODF 1.1, and now ODF 1.2.

This deals with the technical prospect for embedding.  The use cases, implementation notes, and above all the means for choosing embeddings, honoring licenses, etc., require a roadmap of progressive improvements.  And there is already here the least that could possibly work and can be used for some trials and resiliency testing with existing ODF consumers.

 - Dennis

PS: It was considered that a special kind of xlink:href could be used to directly embed font data in the single-XML document case.  A better, less-dangerous approach would be to allow an <office:binary-data> element as an alternative child in those places where an xlink:href is an option.  There would need to be another way to know the MIME type and it is probably time to add some attributes to the <office:binary-data> element to facilitate that.  This would require down-the-road, ODF 1.3+ work.

-----Original Message-----
From: Dennis E. Hamilton [mailto:dennis.hamilton@acm.org] 
Sent: Tuesday, December 13, 2011 17:03
To: ooo-dev@incubator.apache.org
Cc: 'Gianluca Turconi'; 'Bart Hanssens '
Subject: RE: [FONTS] Embedding in ODF (was RE: old colored vs new monochrome icons)

[Fixed the name of the thread]

I'm also calendar challenged.  The OIC TC teleconference is on 2011-12-14 (not -13) at 1430 UTC.

People known to this list who participate on the OIC TC include Rob Weir, Svante Schubert, Don Harbison, Louis Suarez-Potts, and Andrew Rist.

There are even more familiar faces on the ODF TC, which has its last 2011 call on 12-19.

I recall from list exchanges about the embedded font case that there is a simple addition to the current provision that would allow embedding in even the single-XML version of ODF documents.  That would also be a superior way to embed fonts that should not be easily extracted from ODF packages.  Although that would be more likely for ODF 1.3, it might be worked into a draft before that and also be available for experimental use as an ODF 1.2 extension.

Enough.  First, I need to go verify that the sample and make sure that it doesn't use anything not already provided for in ODF.

 - Dennis


-----Original Message-----
From: Dennis E. Hamilton [mailto:dennis.hamilton@acm.org] 
Sent: Tuesday, December 13, 2011 10:47
To: ooo-dev@incubator.apache.org
Cc: 'Gianluca Turconi'; Bart Hanssens ; 'Jos van den Oever'
Subject: [FONTS] Inclusion in ODF (was RE: old colored vs new monochrome icons)

A short time before the most-recent ODF Plugfest, Jos van den Oever demonstrated that ODF already has a means by which fonts can be embedded in the ODF document.  (I will dig up appropriate links when I am more awake.)

So, in fact, a *technical* solution seems to exist.  (Most of the debates about font embedding that I have been party to are around the legal and licensing niceties and avoiding becoming a contributory infringer by not handling this well. This is not entirely unlike issues around bundling of extensions that have license limitations [;<)

Staying on the technical side of the issue, the following is now known:

 1. Fonts can be embedded in ODF documents, using existing and long-present provisions of the ODF specification.  [There was some confusion about using CSS and XLink provisions but, as I recall, it is actually very simple and does not require any extension to the format or schema.  I will have to double-check that.)

There is now need for the following:

 2. Some (more) proof-of-concept sample documents that demonstrate such embedding need to be collected as test vehicles.  [Any solution applies to all ODF formats - text, spreadsheet, presentation, ... - that have a font section and definable styles in the format.]

 3. It needs to be determined what happens with ODF consumers when such unexpected documents are encountered.

 4. There needs to be some staging among ODF producers to support embedding in implementations (LO, AOO, Microsoft Office), etc.  There also needs to be upgrading of conversion software so that font embeddings can now be ported between formats that support them (and will make very many people very happy).  Consumers need to be upgraded at the same time or even ahead of producers.  There is also a concern for what happens when a down-level release encounters one of these ODF files, of course.

 5. A GREAT DEAL OF INTEROP TESTING AND RELEASE STAGING IS CALLED FOR.  (More security analysis is also needed because font injection is an exploit path and there have been past vulnerabilities around fonts.)  

 6. The next ODF Plugfest is scheduled for April in Brussels.  Now is a great time for moving proof-of-concept/prototype/finished/collaborative work forward for introduction and presentation on the agenda of that event.  The OASIS ODF Interoperability and Conformance TC has some resources (even an SVN for sample documents and test cases) and the Plugfest mailing list can be a valuable neutral forum.  (The last TC call of 2011 is tomorrow, 12-13, and this will definitely be discussed.)

 7. With regard to pro-active support and the interfaces necessary to control embedding, embedded-font usage, and when and how embedded fonts can be extracted and/or repurposed in other documents, there may need to be some technical support, and that will be a longer discussion that may require extended staging to be fully functional.  (It is in the nature of the ODF format that direct extraction of fonts embedded in the current structure is trivial for any teen-age hacker, with no cooperation of an ODF consumer required.)  Down the road, there may need to be more-specific consideration of font embedding in the ODF Specification beyond the current, simple hook.

 8. I suspect that there are cases that can be handled without too much difficulty and useful embedding can happen soon, with enrichment of the feature and functionality over time.



 - Dennis E. Hamilton
   tools for document interoperability,  <http://nfoWorks.org/>
   dennis.hamilton@acm.org  gsm: +1-206-779-9430  @orcmid




-----Original Message-----
From: Gianluca Turconi [mailto:public@letturefantastiche.com] 
Sent: Tuesday, December 13, 2011 09:13
To: ooo-dev@incubator.apache.org
Subject: Re: old colored vs new monochrome icons

[ ... ]

P.S. to whom is interested, the most wanted future by the usenet
Italian community (IMO) is font inclusion in OO Writer documents. It
caused flame wars, endless legal discussions starting
from Agfa vs. Adobe trial and a huge addition to my kill file. :-P 
-- 
Lettura gratuita o acquisto di libri e racconti di fantascienza, 
fantasy, horror, noir, narrativa fantastica e tradizionale:
http://www.letturefantastiche.com/