[Okular-devel] How to best express annotations
Jakob Voss
jakob.voss at gbv.de
Thu Nov 4 12:26:55 CET 2010
Hi,
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.
Jakob
--
Jakob Voß <jakob.voss at gbv.de>, skype: nichtich
Verbundzentrale des GBV (VZG) / Common Library Network
Platz der Goettinger Sieben 1, 37073 Göttingen, Germany
+49 (0)551 39-10242, http://www.gbv.de
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