[Okular-devel] Re: How to best express annotations

[Albert Astals Cid]

A Divendres, 5 de novembre de 2010, Jakob Voss va escriure:
> Albert Astals Cid wrote:
> >> Apparently annotations are an issue that is still not resolved. You
> >> should be able to read and modify annotations that were created by other
> >> PDF readers, but poppler does not support it. There are also good
> >> reasons to store annotations separated from the original document. But
> >> each applications seems to have its own proprietary format to store and
> >> exchange annotations. I summarized some notes here:
> >> 
> >> https://github.com/nichtich/marginalia/wiki/Support-of-PDF-annotations
> >> 
> >> It looks like Okular uses its own proprietary format to express
> >> annotations in metadata.xml. Can you point me to any documentation of
> >> this format? How does it compare to the format used by other
> >> applications (Xournal, iAnnotate, Evernote etc.).
> >> 
> >> You could transform okular annotations to PDF annotations, and vice
> >> versa. The iText PDF library seems to support reading and adding PDF
> >> annotations. A simple sample script can be found at:
> >> 
> >> https://github.com/nichtich/marginalia
> >> 
> >> you should be able to get it running thanks to Maven, which makes
> >> programming in Java suck at least less. But before programming a
> >> converter for each custom annotation format - why not just using a
> >> subset of XFDF? XFDF is known for storing PDF form data, but it also
> >> supports PDF annotations in XML:
> >> 
> >> XML Forms Data Format Specification (XFDF) 2.0 (2007).
> >> http://partners.adobe.com/public/developer/en/xml/xfdf_2.0.pdf
> >> 
> >> PDF annotations are defined in chapter 8.4 of the PDF reference (2006),
> >> page 604-647. see
> >> http://www.verypdf.com/document/pdf-format-reference/pg_0604.htm
> >> 
> >> Anyway, a standard file format for Annotations which can be extracted
> >> from and added to PDF files, would be best.
> > 
> > We do know how to improve Annotation support in Okular, it's just that we
> > do not have time for it.
> 
> Well, does this knowledge only exist in your heads, 

Yes

> or can you point me
> to some documentation, plans etc.? As far as I understand support of
> embedded annotations depend on poppler, but external annotations can be
> improved independent from that.
> 
> I know found that the important parts of Annotation format are located
> in class Okular::Annotation, and in the methods
> Okular::Annotation::store and Okular::AnnotationUtils::storeAnnotation.
> 
>  > Forgot to say that if you have time you are very welcome to help :-)
> 
> My strategy is to create a tool to both extract annotations from a PDF,
> and to merge annotations with a PDF. Okular file format could be used
> for the step between, but I'd strongly prefer a standardized format like
> XFDF, that can also be used by other clients.

Patches welcome :-)

BTW if you feel you like a more real time discussion we are usually online in 
IRC in european evenings at the #okular channel in the freenode network.

Albert

> 
> Cheers
> Jakob