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244 lines
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244 lines
10 KiB
Plaintext
Next
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====
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*** ABI changes have been made. build.mk has been updated.
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* 64-bit windows build, remaining steps
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- new external-libs have been built and copied into
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~/Q/storage/releases/qpdf/external-libs. Release is done in
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git. Just need to upload when ready. Remember to document that
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this version is needed for > 2.3.1.
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- update README-windows.txt docs to indicate that MSVC 2010 is the
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supported version and to update the information about mingw,
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including the need for the _FILE_OFFSET_BITS workaround on the
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32-bit version.
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* Document that your compiler has to support long long.
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* Make sure that the release notes call attention to the one API
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breaking change: removal of length from replaceStreamData.
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* Document thread safety: One individual QPDF or QPDFWriter object
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can only be used by one thread at a time, but multiple threads can
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simultaneously use separate objects.
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* Mention QPDFObjectHandle::parse in the documentation.
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* Manual: empty --empty as an input file name option
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* copyForeignObject, merge/split documentation:
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document details of --pages option in manual. Include nuances of
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range parsing, such as backward ranges and "z". Discuss
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implications of using --empty vs. using one of the source files as
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the original file including Outlines (which basically work) and
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page labels (which don't). Also mention trick of specifying two
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different paths to the same file get duplication.
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Command line is
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--pages infile [ --password=pwd ] range ... --
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The regular input referenced would be the one whose other data
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would be preserved (like trailer, info, encryption, outlines,
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etc.). It can be but doesn't have to be one of the files selected.
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Example: to grab pages 1-5 from file1 and 11-15 from file2 in
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reverse:
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qpdf file1.pdf out.pdf --pages file1.pdf 1-5 file2.pdf 15-11 --
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Use comments in qpdf.cc to guide internals documentation when
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discussing implementation. Also see copyForeignObject as a source
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for documentation.
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Document that makeIndirectObject doesn't handle foreign objects
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automatically because copying a foreign object is a big enough deal
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that it should be explicit. However addPages* does handle foreign
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page objects automatically.
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* Document --copy-encryption and --encryption-file-password in
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manual. Mention that the first half of /ID as well as all the
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encryption parameters are copied. Maybe mention about StrF and
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StrM with respect to AES here and also with encryption
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preservation.
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Soon
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====
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* See if I can support the new encryption formats mentioned in the
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open bug on sourceforge. Check other sourceforge bugs.
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General
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=======
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* Look for %PDF header somewhere within the first 1024 bytes of the
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file. Also accept headers of the form "%!PS−Adobe−N.n PDF−M.m".
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See Implementation notes 13 and 14 in appendix H of the PDF 1.7
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specification. This is bug 3267974.
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* Update qpdf docs about non-ascii passwords. See thread from
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2010-12-07,08 for details.
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* Consider impact of article threads on page splitting/merging.
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Subramanyam provided a test file; see ../misc/article-threads.pdf.
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Email Q-Count: 431864 from 2009-11-03. Other things to consider:
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outlines, page labels, thumbnails, zones. There are probably
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others.
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* See whether it's possible to remove the call to
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flattenScalarReferences. I can't easily figure out why I do it,
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but removing it causes strange test failures in linearization. I
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would have to study the optimization and linearization code to
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figure out why I added this to begin with and what in the code
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assumes it's the case. For enqueueObject and unparseChild in
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QPDFWriter, simply removing the checks for indirect scalars seems
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sufficient. Looking back at the branch in the apex epub
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repository, before flattening scalar references, there was special
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case code in QPDFWriter to avoid writing out indirect nulls. It's
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still not obvious to me why I did it though.
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To pursue this, remove the call to flattenScalarReferences in
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QPDFWriter.cc and disable the logic_error exceptions for indirect
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scalars. Just search for flattenScalarReferences in QPDFWriter.cc
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since the logic errors have comments that mention
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flattenScalarReferences. Then run the test suite. Several files
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that explicitly test flattening of scalar references fail, but the
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indirect scalars are properly preserved and written. But then
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there are some linearized files that have a bunch of unreferenced
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objects that contain scalars. Need to figure out what these are
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and why they're there. Maybe they're objects that used to be
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stream lengths. Probably we just need to make sure don't traverse
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through a stream's /Length stream when enqueueing stream
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dictionaries. This could potentially happen with any object that
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QPDFWriter replaces when writing out files. Such objects would be
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orphaned in the newly written file. This could be fixed, but it
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may not be worth fixing.
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If flattenScalarReferences is removed, a new method will be needed
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for checking PDF files.
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* See if we can avoid preserving unreferenced objects in object
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streams even when preserving the object streams.
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* For debugging linearization bugs, consider adding an option to save
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pass 1 of linearization. This code is sufficient. Change the
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interface to allow specification of a pass1 file, which would
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change the behavior as in this patch.
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------------------------------
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Index: QPDFWriter.cc
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===================================================================
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--- QPDFWriter.cc (revision 932)
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+++ QPDFWriter.cc (working copy)
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@@ -1965,11 +1965,15 @@
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// Write file in two passes. Part numbers refer to PDF spec 1.4.
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+ FILE* XXX = 0;
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for (int pass = 1; pass <= 2; ++pass)
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{
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if (pass == 1)
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{
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- pushDiscardFilter();
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+// pushDiscardFilter();
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+ XXX = fopen("/tmp/pass1.pdf", "w");
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+ pushPipeline(new Pl_StdioFile("pass1", XXX));
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+ activatePipelineStack();
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}
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// Part 1: header
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@@ -2204,6 +2208,8 @@
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// Restore hint offset
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this->xref[hint_id] = QPDFXRefEntry(1, hint_offset, 0);
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+ fclose(XXX);
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+ XXX = 0;
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}
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}
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}
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------------------------------
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* Handle embedded files. PDF Reference 1.7 section 3.10, "File
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Specifications", discusses this. Once we can definitely recongize
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all embedded files in a docucment, we can update the encryption
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code to handle it properly. In QPDF_encryption.cc, search for
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cf_file. Remove exception thrown if cf_file is different from
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cf_stream, and write code in the stream decryption section to use
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cf_file instead of cf_stream. In general, add interfaces to get
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the list of embedded files and to extract them. To handle general
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embedded files associated with the whole document, follow root ->
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/Names -> /EmbeddedFiles -> /Names to get to the file specification
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dictionaries. Then, in each file specification dictionary, follow
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/EF -> /F to the actual stream. There may be other places file
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specification dictionaries may appear, and there are also /RF keys
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with related files, so reread section 3.10 carefully.
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* The description of Crypt filters is unclear with respect to how to
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use them to override /StmF for specific streams. I'm not sure
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whether qpdf will do the right thing for any specific individual
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streams that might have crypt filters. The specification seems to
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imply that only embedded file streams and metadata streams can have
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crypt filters, and there are already special cases in the code to
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handle those. Most likely, it won't be a problem, but someday
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someone may find a file that qpdf doesn't work on because of crypt
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filters. There is an example in the spec of using a crypt filter
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on a metadata stream.
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For now, we notice /Crypt filters and decode parameters consistent
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with the example in the PDF specification, and the right thing
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happens for metadata filters that happen to be uncompressed or
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otherwise compressed in a way we can filter. This should handle
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all normal cases, but it's more or less just a guess since I don't
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have any test files that actually use stream-specific crypt filters
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in them.
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* The second xref stream for linearized files has to be padded only
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because we need file_size as computed in pass 1 to be accurate. If
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we were not allowing writing to a pipe, we could seek back to the
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beginning and fill in the value of /L in the linearization
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dictionary as an optimization to alleviate the need for this
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padding. Doing so would require us to pad the /L value
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individually and also to save the file descriptor and determine
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whether it's seekable. This is probably not worth bothering with.
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* The whole xref handling code in the QPDF object allows the same
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object with more than one generation to coexist, but a lot of logic
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assumes this isn't the case. Anything that creates mappings only
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with the object number and not the generation is this way,
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including most of the interaction between QPDFWriter and QPDF. If
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we wanted to allow the same object with more than one generation to
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coexist, which I'm not sure is allowed, we could fix this by
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changing xref_table. Alternatively, we could detect and disallow
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that case. In fact, it appears that Adobe reader and other PDF
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viewing software silently ignores objects of this type, so this is
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probably not a big deal.
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* Pl_PNGFilter is only partially implemented. If we ever decoded
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images, we'd have to finish implementing it along with the other
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filter decode parameters and types. For just handling xref
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streams, there's really no need as it wouldn't make sense to use
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any kind of predictor other than 12 (PNG UP filter).
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* If we ever want to have check mode check the integrity of the free
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list, this can be done by looking at the code from prior to the
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object stream support of 4/5/2008. It's in an if (0) block and
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there's a comment about it. There's also something about it in
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qpdf.test -- search for "free table". On the other hand, the value
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of doing this seems very low since no viewer seems to care, so it's
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probably not worth it.
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* QPDFObjectHandle::getPageImages() doesn't notice images in
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inherited resource dictionaries. See comments in that function.
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* Based on an idea suggested by user "Atom Smasher", consider
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providing some mechanism to recover earlier versions of a file
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embedded prior to appended sections.
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* From a suggestion in bug 3152169, consisder having an option to
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re-encode inline images with an ASCII encoding.
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