Toying with using "qpdf" on PDFs...

Previous Topic Next Topic
classic Classic list List threaded Threaded
1 message Options
Reply | Threaded
Open this post in threaded view

Toying with using "qpdf" on PDFs...


More on PDFs:  I'm slogging slowly towards having Tecgraf IM/CD/IUP
graphical tools available on GNU/Linux platforms that I use; part
of the effort in porting is contemplating a regression test rig.

Provided that a PDF is not encrypted, "qpdf" can unpack (undo zlib
compression) on a PDF, and is able to select page(s) to operate on.

Two identical runs of a short script that uses CD (Canvas Draw),
then draws some extremely simple primitives on it, and then saves it
as a PDF, result in a difference -- at least, there is a different
timestamp in the header.

Once qpdf has unpacked the PDF back into its PostScript text
format, the timestamp can be set to a nominal time (e.g. using a
simple text editing tool such as "sed", and the differences between
the PDFs becomes smaller.  [There's also what may be a checksum and
possibly an encryption/signature line at the end of the file; these
can also be text-edited to eliminate variance.]

This looks like a promising avenue for building a regression test
rig in the future; for now, there's too much groundwork/framework to
be laid first in order to release my "IM/CD/IUP Assistant", and so
things like "qpdf" have to remain on the back-burner for me at present.

However, this tool may be of interest as it can provide various ways of
manipulating PDFs, including splitting apart large files into smaller


sur-behoffski (Brenton Hoff)   (*NOT TO BE CONFUSED WITH "BIG SUR"*)
programmer, Grouse Software