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2.1
===
* Update documentation to reflect new command line flags and any
other relevant changes. Should read through ChangeLog and the
manual before releasing 2.1.
* Write documentation section on source-level API changes between 2.0
and 2.1.
* Windows release: config for both compilers, make install. Create
zip files. Probably should put the compiler name somewhere in the
directory (qpdf-version-compiler?). Need some kind of "what to
download" file.
* Make install for windows: copy system DLLs as needed excluding
msvcrt and kernel32. Update README.windows in this case including
taking out the mention of strip since it should be handled by the
install step. Make sure it works to link with the static library
when the dll is not in the same directory.
* Add comments for the security functions that map them back to the
items in Adobe's products.
* "Delphi wrapper unit 'qpdf.pas' created by Zarko Gajic
(http://delphi.about.com). .. use at your own risk and for whatever
the purpose you want .. no support provided. Sample code provided."
2.2
===
* Add ability to create new streams or replace stream data. Consider
stream data sources to include a file and offset, a buffer, or a
some kind of callback mechanism. Find messages exchanged with
Stefan Heinsen <stefan.heinsen@gmx.de> in August, 2009. He seems
to like to send encrypted mail. (key 01FCC336)
* Look at page splitting.
General
=======
* Handle embedded files. PDF Reference 1.7 section 3.10, "File
Specifications", discusses this. Once we can definitely recongize
all embedded files in a docucment, we can update the encryption
code to handle it properly. In QPDF_encryption.cc, search for
cf_file. Remove exception thrown if cf_file is different from
cf_stream, and write code in the stream decryption section to use
cf_file instead of cf_stream. In general, add interfaces to
get the list of embedded files and to extract them. To handle
general embedded files associated with the whole document, follow
root -> /Names -> /EmbeddedFiles -> /Names to get to the file
specification dictionaries. Then, in each file specification
dictionary, follow /EF -> /F to the actual stream.
* The description of Crypt filters is unclear with respect to how to
use them to override /StmF for specific streams. I'm not sure
whether qpdf will do the right thing for any specific individual
streams that might have crypt filters. The specification seems to
imply that only embedded file streams and metadata streams can have
crypt filters, and there are already special cases in the code to
handle those. Most likely, it won't be a problem, but someday
someone may find a file that qpdf doesn't work on because of crypt
filters. There is an example in the spec of using a crypt filter
on a metadata stream.
For now, we notice /Crypt filters and decode parameters consistent
with the example in the PDF specification, and the right thing
happens for metadata filters that happen to be uncompressed or
otherwise compressed in a way we can filter. This should handle
all normal cases, but it's more or less just a guess since I don't
have any test files that actually use stream-specific crypt filters
in them.
* The second xref stream for linearized files has to be padded only
because we need file_size as computed in pass 1 to be accurate. If
we were not allowing writing to a pipe, we could seek back to the
beginning and fill in the value of /L in the linearization
dictionary as an optimization to alleviate the need for this
padding. Doing so would require us to pad the /L value
individually and also to save the file descriptor and determine
whether it's seekable. This is probably not worth bothering with.
* The whole xref handling code in the QPDF object allows the same
object with more than one generation to coexist, but a lot of logic
assumes this isn't the case. Anything that creates mappings only
with the object number and not the generation is this way,
including most of the interaction between QPDFWriter and QPDF. If
we wanted to allow the same object with more than one generation to
coexist, which I'm not sure is allowed, we could fix this by
changing xref_table. Alternatively, we could detect and disallow
that case. In fact, it appears that Adobe reader and other PDF
viewing software silently ignores objects of this type, so this is
probably not a big deal.
* Pl_PNGFilter is only partially implemented. If we ever decoded
images, we'd have to finish implementing it along with the other
filter decode parameters and types. For just handling xref
streams, there's really no need as it wouldn't make sense to use
any kind of predictor other than 12 (PNG UP filter).
* If we ever want to have check mode check the integrity of the free
list, this can be done by looking at the code from prior to the
object stream support of 4/5/2008. It's in an if (0) block and
there's a comment about it. There's also something about it in
qpdf.test -- search for "free table". On the other hand, the value
of doing this seems very low since no viewer seems to care, so it's
probably not worth it.
* QPDFObjectHandle::getPageImages() doesn't notice images in
inherited resource dictionaries. See comments in that function.
* Based on an idea suggested by user "Atom Smasher", consider
providing some mechanism to recover earlier versions of a file
embedded prior to appended sections.
Splitting by Pages
==================
Although qpdf does not currently support splitting a file into pages,
the work done for linearization covers almost all the work. To do
page splitting. If this functionality is needed, study
obj_user_to_objects and object_to_obj_users created in
QPDF_optimization for ideas. It's quite possible that the information
computed by calculateLinearizationData is actually sufficient to do
page splitting in many circumstances. That code knows which objects
are used by which pages, though it doesn't do anything page-specific
with outlines, thumbnails, page labels, or anything else.
Another approach would be to traverse only pages that are being output
taking care not to traverse into the pages tree, and then to fabricate
a new pages tree.
Either way, care must be taken to handle other things such as
outlines, page labels, thumbnails, threads, zones, etc. in a sensible
way. This may include simply omitting information other than page
content.
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