Re: [evince] what missing functionality is this document using?

["D. Hugh Redelmeier" <hugh mimosa com>]

| From: "jose aliste gmail com" <jose aliste gmail com>

| On Wed, Jan 19, 2011 at 5:26 PM, D. Hugh Redelmeier <hugh mimosa com> wrote:

| > I'm trying to fill out this form.
| > <http://www.passport.gc.ca/form/pdfs/pptc054.pdf>

| > 3) is there any way for a user to know that some feature of a document is
| >   not being rendered by Evince?
| 
| The only way is the natural one, open the pdf with Evince and
| acroread, I am not aware of any other method.

I think that it would be good for evince to tell me that it isn't
doing something that the document specifies.  I quite understand not
implementing some features, but silently doing so isn't as good.

================

For the record, I'll document some problems I had trying to fill out
this government form.  (I mention "government" because I don't like
proprietary programs being forced on me by my government.)

The fonts in my Linux system must be a little different from those
that the pdf creator used: text didn't properly fit in boxes.  But
it was "close enough for government work" as they say.

One funny example: checked tick boxes looked like they had " marks
rather than check marks.  Today the passport officer did ask me about
that.

When I went to save the filled in form, I got a warning that the
form was encrypted and Evince refused to save it.  I sure would have
liked to know BEFORE I went to the work of filling it in.

(One reason that I had not used Adobe Reader to fill in the form was
because AR does not allow saving.  I hate starting from scratch
every time.)

I googled and found that this was a known limitation.
<https://bugs.launchpad.net/ubuntu/+source/evince/+bug/492959>
So I unencrypted the document:
	qpdf --decrypt original.pdf unencrypted.pdf

(If the original was encrypted, how come I could read it?  Is it
actually just authenticated with a cryptographic signature?  That
would make more sense.)

I then filled out the form again, starting from the unencrypted pdf.
I could save it!

I tried to view the filled in document with AR9 (on WinXP).  I wanted
to use the form's "validate and print" button to check my work.
But AR9 would not load the saved copy.  It said:

	This document enabled extended features in Adobe Reader.  The
	document has been changed since it was created and use of
	extended features is no longer available.  Please contact the
	author for the original version of the document.

Is this just a polite way of saying that this document was originally
signed and it isn't any longer?

Anyway, the upshot is that I cannot verify my work because Evince
doesn't implement JavaScript and AR9 doesn't like forms filled by
Evince.