[Okular-devel] Possible bug with annotations?

[Fabio D'Urso]

On Monday, December 16, 2013 10:19:08 PM Albert Astals Cid wrote:
> El Dilluns, 16 de desembre de 2013, a les 17:16:20, Edward Rosten va 
escriure:
> > Hi All,
> 
> Hi
> 
> > I'm having a problem with annotations and I'm not sure if it's a bug.
> > 
> > I've attached 3 files. The original is hello.pdf, a very plain PDF
> > made with PDFlatex.
> > 
> > The next file hello-okular.pdf has been annotated with okular. The
> > problem with this file is that annotations don't appear in all
> > readers. They don't appear in xpdf and (worse) don't appear in the PDF
> > reader built into gmail, or the one built into Firefox. They do appear
> > in evince, okular and Acrobat Reader.
> > 
> > For the final file, I loaded hello-okular.pdf into Acrobat Reader and
> > saved as hello-okular-adobereader.pdf without making any explicit
> > modifications. Now the annotations appear in all readers.
> > 
> > It appears that the annotations only semi-work in other PDF readers at
> > the moment. I also have a vague memory which I can't verify that
> > okular annotations have previously been readable in xpdf (and
> > presumably the others, though I don't remember).
> > 
> > Is this a bug?
> 
> Looks like it to me. What could be otherwise?

Sounds like xpdf, gmail and Firefox don't know how to handle annotations 
without an appearance stream (Poppler -the library we use to handle PDFs- 
doesn't store the appearance stream within the PDF file, whereas Acrobat 
does). Basically we're saying "you have to draw a circle annotation" but we're 
not telling how (ie "draw a curve using these control points").

If they used to work, then I'm wrong and it is a bug.


According to the specs the appearance stream is optional, therefore I'm 
tempted to say this is not our/Poppler's bug. OTOH, given that so many readers 
show this issue, we may want to change Poppler's behavior.

There is a reason why I haven't done this yet: we would need to embed a font 
in case of text notes, but I don't know enough about fonts to do that and I 
guess there are also licensing issues to keep in mind.

Albert, what do you think?

Fabio

> Cheers,
>   Albert
> 
> > Regards
> > 
> > -Ed
> 
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-- 
Fabio