[poppler] Filled text field data not visible in saved document

Albert Astals Cid aacid at kde.org
Sun Oct 14 09:32:11 PDT 2012

El Diumenge, 14 d'octubre de 2012, a les 02:49:09, Fabio D'Urso va escriure:
> On Tuesday, September 18, 2012 07:52:23 PM Albert Astals Cid wrote:
> > El Dimarts, 18 de setembre de 2012, a les 07:49:05, vau escriure:
> > > Hi Albert, Hi Fabio,
> > > 
> > > the solution from Fabio worked quite well to me.
> > > There are still some PDFs remaining which do not have their application
> > > stream changed - at least it looks like that.
> > > 
> > > But for most of the files I tried it works fine.
> > > Hence, a big "thank you" to Fabio and I would recommend to apply that
> > > patch to an upcoming release.
> > 
> > Spoke with Fabio in private and he seems not to be happy with it, he'll be
> > working in a better one once he gets a bit of time.
> Here we go. I've rewritten the patches in a cleaner way and now I'm
> satisfied with them.
> Short recap: After filling and saving a PDF form, filled text fields are
> still shown with their old value (usually blank) in acroread (and in
> poppler too, when you open the resulting PDF file) because we don't update
> the annotation widgets' appearance streams.

I think i have a pdf (that i'm not sure i can share) that has the problems you 
describe but doesn't seem to be fixed by the patches, i'll send it your way.


> With these patches, the appearance stream gets rewritten for text and
> choice fields (for button fields it's not necessary).
> Note that choice fields still don't work in acroread, because of some
> unrelated issues that I'll discuss in a new thread.
> Patches in detail:
> 0001
> Patch 0001 adds a AnnotWidget::updateAppearanceStream() method that is
> called by form handling code to inform the widget annotation that its
> appearance stream is no longer valid and needs to be rebuilt.
> This information was previously obtained by the widget annotation by testing
> field->isModified() before drawing. This new "push" approach has two
> advantages:
> 1) The appearance is now rebuilt only once after the contents are modified.
> Previously, field->isModified() stayed always true, even after the first
> draw() call, causing the apperance stream to be rebuilt on every subsequent
> draw() call too, even if contents stayed the same.
> 2) It gives the possibility to react to modifications immediatly, without
> having to wait for the next rendering.
> 0002
> This patch creates the new appearance stream in
> AnnotWidget::updateAppearanceStream() and writes it in the xref. This patch
> fixes the original bug, but...
> Note: ...every time the field is modified (eg in okular it happens every
> time the the user adds or removes a character) the old apprearance stream
> is deleted and a new one is generated. This means that the xref entry for
> the old appearance is freed and a new one is allocated. Since every time a
> xref entry is freed its generation number gets incremented, repeated edits
> result in generation numbers rapidily growing. The next patch solves this
> issue.
> 0003
> This patch avoids going through xref entry deallocation+allocation on every
> modification. Now it only happens the first time, and references to the
> newly allocated xref entry are kept, so that subsequent
> updateAppearanceStream invocations can do a simple overwrite instead.
> These patches are supposed to fix exactly the same documents that the
> previous proof-of-concept patch fixed. Please let me know if you find any
> difference.
> Thank you,
> Fabio

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