# Release Notes

For a detailed list of changes, please see the file `ChangeLog` in the source distribution.

11.1.1: October 1, 2022

  - Bug fixes

    - Fix edge case with character encoding for strings whose initial characters happen to coincide with Unicode markers.

    - Fix issue with AppImage discarding the first command-line argument when invoked as the name of one of the embedded executables. Also, fix-qdf, for unknown reasons, had the wrong runpath and would use a qpdf library that was installed on the system.

  - Test improvements

    - Exercise the case of `char` being `unsigned` by default in automated tests.

    - Add AppImage-specific tests to CI to ensure that the AppImage works in the various ways it is intended to be invoked.

  - Other changes

    - Include more code tidying and performance improvements from M. Holger.

11.1.0: September 14, 2022

  - Build fixes

    - Remove `LL_FMT` tests, which were broken for cross compilation. The code just uses `%lld` now.

    - Some symbols were not properly exported for the Windows DLL build.

    - Force project-specific header files to precede all others in the build so that a previous qpdf installation won’t break building qpdf from source.

  - Packaging note omitted from 11.0.0 release notes:

    - On GitHub, the release tags are now `vX.Y.Z` instead of `release-qpdf-X.Y.Z` to be more consistent with current practice.

11.0.0: September 10, 2022

  - Replacement of `PointerHolder` with `std::shared_ptr`

    - The qpdf-specific `PointerHolder` smart pointer implementation has now been completely replaced with `std::shared_ptr` through the qpdf API. Please see Smart Pointers for details about this change and a comprehensive migration plan. Note that a backward-compatible `PointerHolder` class is provided and is enabled by default. A warning is issued, but this can be turned off by following the migration steps outlined in the manual.

  - qpdf JSON version 2

    - qpdf’s JSON output mode is now at version 2. This fixes several flaws with version 1. Version 2 JSON output is unambiguous and complete, and bidirectional conversion between JSON and PDF is supported. Command-line options and library API are available for creating JSON from PDF, creating PDF from JSON and updating existing PDF at the object level from JSON.

    - New command-line arguments: `--json-output`, `--json-input`, `--update-from-json`

    - New C++ API calls: `QPDF::writeJSON`, `QPDF::createFromJSON`, `QPDF::updateFromJSON`

    - New C API calls: `qpdf_create_from_json_file`, `qpdf_create_from_json_data`, `qpdf_update_from_json_file`, `qpdf_update_from_json_data`, and `qpdf_write_json`.

    - Complete documentation can be found at qpdf JSON. A comprehensive list of changes from version 1 to version 2 can be found at Changes from JSON v1 to v2.

  - Build replaced with cmake

    - The old autoconf-based build has been replaced with CMake. CMake version 3.16 or newer is required. For details, please read Building and Installing QPDF and, if you package qpdf for a distribution, Notes for Packagers.

    - For the most part, other than being familiar with generally how to build things with cmake, what you need to know to convert your build over is described in Converting From autoconf to cmake. Here are a few changes in behavior to be aware of:

      - Example sources are installed by default in the documentation directory.

      - The configure options to enable image comparison and large file tests have been replaced by environment variables. The old options set environment variables behind the scenes. Before, to skip image tests, you had to set `QPDF_SKIP_TEST_COMPARE_IMAGES=1`, which was done by default. Now these are off by default, and you have to set `QPDF_TEST_COMPARE_IMAGES=1` to enable them.

      - In the default configuration, the native crypto provider is only selected when explicitly requested or when there are no other options. See Build-time Crypto Selection for a detailed discussion.

      - Windows external libraries are detected by default if the `external-libraries` directory is found. Static libraries for zlib, libjpeg, and openssl are provided as described in `README-windows.md`. They are only compatible with non-debug builds.

      - A new directory called `pkg-tests` has been added which contains short shell scripts that can be used to smoke test an installed qpdf package. These are used by the debian `autopkgtest` framework but can be used by others. See `pkg-test/README.md` for details.

  - Performance improvements

    - Many performance enhancements have been added. In developer performance benchmarks, gains on the order of 20% have been observed. Most of that work, including major optimization of qpdf’s lexical and parsing layers, was done by M. Holger.

  - CLI: breaking changes

    - The `--show-encryption` flag now provides encryption information even if a correct password is not supplied. If you were relying on its not working in this case, see `--requires-password` for a reliable test.

    - The default json output version when `--json` is specified has been changed from `1` to `latest`, which is now `2`.

    - The `--allow-weak-crypto` flag is now mandatory when explicitly creating files with weak cryptographic algorithms. See Weak Cryptography for a discussion.

  - API: breaking changes

    - Deprecate `QPDFObject.hh` for removal in qpdf 12. The only use case for including `qpdf/QPDFObject.hh` was to get `QPDFObject::object_type_e`. Since 10.5.0, this has been an alias to `qpdf_object_type_e`, defined in `qpdf/Constants.h`. To fix your code, replace any includes of `qpdf/QPDFObject.hh` with `qpdf/Constants.h`, and replace all occurrences of `QPDFObject::ot_` with `::ot_`. If you need your code to be backward compatible to qpdf versions prior to 10.5.0, you can check that the preprocessor symbol `QPDF_MAJOR_VERSION` is defined and `>= 11`. As a stop-gap, you can `#define QPDF_OBJECT_NOWARN` to suppress the warning.

    - `Pipeline::write` now takes `unsigned char const*` instead of `unsigned char*`. Callers don’t need to change anything, but you no longer have to pass writable pointers to pipelines. If you’ve implemented your own pipeline classes, you will need to update them.

    - Remove deprecated `QPDFAcroFormDocumentHelper::copyFieldsFromForeignPage`. This method never worked and only did something in qpdf version 10.2.x.

    - Remove deprecated `QPDFNameTreeObjectHelper` and `QPDFNumberTreeObjectHelper` constructors that don’t take a `QPDF&` argument.

    - The function passed to and called by `QPDFJob::doIfVerbose` now takes a `Pipeline&` argument instead of a `std::ostream&` argument.

    - Intentionally break API to call attention to operations that write files with insecure encryption:

      - Remove pre qpdf-8.4.0 encryption API methods from `QPDFWriter` and their corresponding C API functions

      - Add `Insecure` to the names of some `QPDFWriter` methods and `_insecure` to the names of some C API functions without otherwise changing their behavior

      - See API-Breaking Changes in qpdf 11.0 for specific details, and see Weak Cryptography for a general discussion.

    - `QPDFObjectHandle::warnIfPossible` no longer takes an optional argument to throw an exception if there is no description. If there is no description, it writes to the default `QPDFLogger`’s error stream. (`QPDFLogger` is new in qpdf 11—see below.)

    - `QPDF` objects can no longer be copied or assigned to. It has never been safe to do this because of assumptions made by library code. Now it is prevented by the API. If you run into trouble, use `QPDF::create()` to create `QPDF` shared pointers (or create them in some other way if you need backward compatibility with older qpdf versions).

  - CLI Enhancements

    - `qpdf --list-attachments --verbose` includes some additional information about attachments. Additional information about attachments is also included in the `attachments` JSON key with `--json`.

    - For encrypted files, `qpdf --json` reveals the user password when the specified password did not match the user password and the owner password was used to recover the user password. The user password is not recoverable from the owner password when 256-bit keys are in use.

    - `--verbose` and `--progress` may be now used when writing the output PDF to standard output. In that case, the verbose and progress messages are written to standard error.

  - Library Enhancements

    - A new object `QPDFLogger` has been added. Details are in `include/qpdf/QPDFLogger.hh`.

      - `QPDF` and `QPDFJob` both use the default logger by default but can have their loggers overridden. The `setOutputStreams` method is deprecated in both classes.

      - A few things from `QPDFObjectHandle` that used to be exceptions now write errors with the default logger.

      - By configuring the default logger, it is possible to capture output and errors that slipped through the cracks with `setOutputStreams`.

      - A C API is available in `include/qpdf/qpdflogger-c.h`.

      - See examples `examples/qpdfjob-save-attachment.cc` and `examples/qpdfjob-c-save-attachment.cc`.

    - In `QPDFObjectHandle`, new methods `insertItemAndGetNew`, `appendItemAndGetNew`, and `replaceKeyAndGetNew` return the newly added item. New methods `eraseItemAndGetOld`, `replaceKeyAndGetOld`, and `removeKeyAndGetOld` return the item that was just removed or, in the case of `replaceKeyAndGetOld`, a `null` object if the object was not previously there.

    - The `QPDFObjectHandle::isDestroyed` method can be used to detect when an indirect object `QPDFObjectHandle` belongs to a `QPDF` that has been destroyed. Any attempt to unparse this type of `QPDFObjectHandle` will throw a logic error.

    - The `QPDFObjectHandle::getOwningQPDF` method now returns a null pointer rather than an invalid pointer when the owning `QPDF` object has been destroyed. Indirect objects whose owning `QPDF` has been destroyed become invalid. Direct objects just lose their owning `QPDF` but continue to be valid.

    - The method `QPDFObjectHandle::getQPDF` is an alternative to `QPDFObjectHandle::getOwningQPDF`. It returns a `QPDF&` rather than a `QPDF*` and can be used when the object is known to have an owning `QPDF`. It throws an exception if the object does not have an owning `QPDF`. Only indirect objects are guaranteed to have an owning `QPDF`. Direct objects may have one if they were initially read from a PDF input source that is still valid, but it’s also possible to have direct objects that don’t have an owning `QPDF`.

    - Add method `QPDFObjectHandle::isSameObjectAs` for testing whether two `QPDFObjectHandle` objects point to the same underlying object, meaning changes to one will be reflected in the other. Note that this method does not compare the contents of the objects, so two distinct but structurally identical objects will not be considered the same object.

    - New factory method `QPDF::create()` returns a `std::shared_ptr<QPDF>`.

    - New `Pipeline` methods have been added to reduce the amount of casting that is needed:

      - `write`: overloaded version that takes `char const*` in addition to the one that takes `unsigned char const*`

      - `writeCstr`: writes a null-terminated C string

      - `writeString`: writes a std::string

      - `operator <<`: for null-terminated C strings, std::strings, and integer types

    - New `Pipeline` type `Pl_OStream` writes to a `std::ostream`.

    - New `Pipeline` type `Pl_String` appends to a `std::string`.

    - New `Pipeline` type `Pl_Function` can be used to call an arbitrary function on write. It supports `std::function` for C++ code and can also accept C-style functions that indicate success using a return value and take an extra parameter for passing user data.

    - Methods have been added to `QUtil` for converting PDF timestamps and `QPDFTime` objects to ISO-8601 timestamps.

    - Enhance JSON class to better support incrementally reading and writing large amounts of data without having to keep everything in memory.

    - Add new functions to the C API for `qpdfjob` that use a `qpdfjob_handle`. Like with the regular C API for qpdf, you have to call `qpdfjob_init` first, pass the handle to the functions, and call `qpdfjob_cleanup` at the end. This interface offers more flexibility than the old interface, which remains available.

    - Add `QPDFJob::registerProgressReporter` and `qpdfjob_register_progress_reporter` to allow a custom progress reporter to be used with `QPDFJob`. The `QPDFJob` object must be configured to report progress (via command-line argument or otherwise) for this to be used.

    - Add new overloads to `QPDFObjectHandle::StreamDataProvider::provideStreamData` that take `QPDFObjGen const&` instead of separate object ID and generation parameters. The old versions will continue to be supported and are not deprecated.

    - In `QPDFPageObjectHelper`, add a `copy_if_fallback` parameter to most of the page bounding box methods, and clarify in the comments about the difference between `copy_if_shared` and `copy_if_fallback`.

    - Add a move constructor to the `Buffer` class.

  - Other changes

    - On GitHub, the release tags are now vX.Y.Z instead of release-qpdf-X.Y.Z to be more consistent with current practice.

    - In JSON v1 mode, the `"objects"` key now reflects the repaired pages tree if `"pages"` (or any other key that has the side effect of repairing the page tree) is specified. To see the original objects with any unrepaired page tree errors, specify `"objects"` and/or `"objectinfo"` by themselves. This is consistent with how JSON v2 behaves.

    - A new chapter on contributing to qpdf has been added to the documentation. See Contributing to qpdf.

    - The qpdf source code is now formatted automatically with `clang-format`. See Code Formatting for information.

    - Test coverage with `QTC` is enabled during development but compiled out of distributed qpdf binaries by default. This results in a significant performance improvement, especially on Windows. `QTC::TC` is still available in the library and is still usable by end user code even though calls to it made internally by the library are turned off. Internally, there is some additional caching to reduce the overhead of repeatedly reading environment variables at runtime.

    - The test files used by the `performance_check` script at the top of the repository are now available in the qpdf/performance-test-files github repository. In addition to running time, memory usage is also included in performance test results when available. The `performance_check` tool has only been tested on Linux.

    - Lots of code cleanup and refactoring work was contributed in multiple pull requests by M. Holger. This includes the work required to enable detection of `QPDFObjectHandle` objects that belong to destroyed `QPDF` objects.

10.6.3: March 8, 2022

  - Announcement of upcoming change:

    - qpdf 11 will be built with cmake. The qpdf 11 documentation will include detailed migration instructions.

  - Bug fixes:

    - Recognize strings explicitly encoded as UTF-8 as allowed by the PDF 2.0 spec.

    - Fix edge cases with appearance stream generation for form fields whose `/DA` field lacks proper font size specification or that specifies auto sizing. At this time, qpdf does not support auto sizing.

    - Minor, non-functional changes to build and documentation to accommodate a wider range of compilation environments in preparation for migration to cmake.

10.6.2: February 16, 2022

  - Bug fixes:

    - Recognize strings encoded as UTF-16LE as Unicode. The PDF spec only allows UTF-16BE, but most readers accept UTF16-LE as well.

    - Fix a regression in command-line argument parsing to restore a previously undocumented behavior that some people were relying on.

    - Fix one more problem with mapping Unicode to PDF doc encoding

10.6.1: February 11, 2022

  - Fix compilation errors on some platforms

10.6.0: February 9, 2022

  - Preparation for replacement of `PointerHolder`

    The next major release of qpdf will replace `PointerHolder` with `std::shared_ptr` across all of qpdf’s public API. No action is required at this time, but if you’d like to prepare, read the comments in `include/qpdf/PointerHolder.hh` and see Smart Pointers for details on what you can do now to create code that will continue to work with older versions of qpdf and be easier to switch over to qpdf 11 when it comes out.

  - Preparation for a new JSON output version

    - The `--json` option takes an optional parameter indicating the version of the JSON output. At present, there is only one JSON version (`1`), but there are plans for an updated version in a coming release. Until the release of qpdf 11, the default value of `--json` is `1` for compatibility. Once qpdf 11 is out, the default version will be `latest`. If you are depending on the exact format of `--json` for code, you should start using `--json=1` in preparation.

  - New QPDFJob API exposes CLI functionality

    Prior to qpdf 10.6, a lot of the functionality implemented by the qpdf CLI executable was built into the executable itself and not available from the library. qpdf 10.6 introduces a new object, `QPDFJob`, that exposes all of the command-line functionality. This includes a native `QPDFJob` API with fluent interfaces that mirror the command-line syntax, a JSON syntax for specifying the equivalent of a command-line invocation, and the ability to run a qpdf “job” by passing a null-terminated array of qpdf command-line options. The command-line argument array and JSON methods of invoking `QPDFJob` are also exposed to the C API. For details, see QPDFJob: a Job-Based Interface.

  - Other Library Enhancements

    - New `QPDFObjectHandle` literal syntax using C++’s user-defined literal syntax. You can use

          auto oh = "<</Some (valid) /PDF (object)>>"_qpdf;

      to create a QPDFObjectHandle. It is a shorthand for `QPDFObjectHandle::parse`.

    - Preprocessor symbols `QPDF_MAJOR_VERSION`, `QPDF_MINOR_VERSION`, and `QPDF_PATCH_VERSION` are now available and can be used to make it easier to write code that supports multiple versions of qpdf. You don’t have to include any new header files to get these, which makes it possible to write code like this:

          #if !defined(QPDF_MAJOR_VERSION) || QPDF_MAJOR_VERSION < 11
              // do something using qpdf 10 or older API
          #else
              // do something using qpdf 11 or newer API
          #endif

      Since this was introduced only in qpdf version 10.6.0, testing for an undefined value of `QPDF_MAJOR_VERSION` is equivalent to detecting a version prior to 10.6.0.

      The symbol `QPDF_VERSION` is also defined as a string containing the same version number that is returned by `QPDF::QPDFVersion`. Note that `QPDF_VERSION` may differ from `QPDF::QPDFVersion()` if your header files and library are out of sync with each other.

    - The method `QPDF::QPDFVersion` and corresponding C API call `qpdf_get_qpdf_version` are now both guaranteed to return a reference (or pointer) to a static string, so you don’t have to copy these if you are using them in your software. They have always returned static values. Now the fact that they return static values is part of the API contract and can be safely relied upon.

    - New accessor methods for `QPDFObjectHandle`. In addition to the traditional ones, such as `getIntValue`, `getName`, etc., there are a family of new accessors whose names are of the form `getValueAsX`. The difference in behavior is as follows:

      - The older accessor methods, which will continue to be supported, return the value of the object if it is the expected type. Otherwise, they return a fallback value and issue a warning.

      - The newer accessor methods return a boolean indicating whether or not the object is of the expected type. If it is, a reference to a variable of the correct type is initialized.

      In many cases, the new interfaces will enable more compact code and will also never generate type warnings. Thanks to M. Holger for contributing these accessors. Search for `getValueAs` in `include/qpdf/QPDFObjectHandle.hh` for a complete list.

      These are also exposed in the C API in functions whose names start with `qpdf_oh_get_value_as`.

    - New convenience methods in `QPDFObjectHandle`: `isDictionaryOfType`, `isStreamOfType`, and `isNameAndEquals` allow more compact querying of dictionaries. Also added to the C API: `qpdf_oh_is_dictionary_of_type` and `qpdf_oh_is_name_and_equals`. Thanks to M. Holger for the contribution.

    - New convenience method in `QPDFObjectHandle`: `getKeyIfDict` returns null when called on null and otherwise calls `getKey`. This makes it easier to access optional, lower-level dictionaries. It is exposed in the C API `qpdf_oh_get_key_if_dict`. Thanks to M. Holger for the contribution.

    - New functions added to `QUtil`: `make_shared_cstr` and `make_unique_cstr` copy `std::string` to `std::shared_ptr<char>` and `std::unique_ptr<char[]>`. These are alternatives to the existing `QUtil::copy_string` function which offer other ways to get a C string with safer memory management.

    - New function `QUtil::file_can_be_opened` tests to see whether a file can actually be opened by attempting to open it and close it again.

    - There is a new version of `QUtil::call_main_from_wmain` that takes a `const` argv array and calls a main that takes a `const` argv array.

    - `QPDF::emptyPDF` has been exposed to the C API as `qpdf_empty_pdf`. This makes it possible to create a PDF from scratch with the C API.

    - New C API functions `qpdf_oh_get_binary_utf8_value` and `qpdf_oh_new_binary_unicode_string` take length parameters, which makes it possible to handle UTF-8-encoded C strings with embedded NUL characters. Thanks to M. Holger for the contribution.

    - There is a new `PDFVersion` class for representing a PDF version number with the ability to compare and order PDF versions. Methods `QPDF::getVersionAsPDFVersion` and a new version of `QPDFWriter::setMinimumPDFVersion` use it. This makes it easier to create an output file whose PDF version is the maximum of the versions across all the input files that contributed to it.

    - The `JSON` object in the qpdf library has been enhanced to include a parser and the ability to get values out of the `JSON` object. Previously it was a write-only interface. Even so, qpdf’s `JSON` object is not intended to be a general-purpose JSON implementation as discussed in `include/qpdf/JSON.hh`.

    - The `JSON` object’s “schema” checking functionality now allows for optional keys. Note that this “schema” functionality doesn’t conform to any type of standard. It’s just there to help with error reporting with qpdf’s own JSON support.

  - Documentation Enhancements

    - Documentation for the command-line tool has been completely rewritten. This includes a top-to-bottom rewrite of Running qpdf in the manual. Command-line arguments are now indexed, and internal links can appear to them within the documentation.

    - The output of `qpdf --help` is generated from the manual and is divided into help topics that parallel the sections of the manual. When you run `qpdf --help`, instead of getting a Great Wall of Text, you are given basic usage information and a list of help topics. It is possible to request help for any individual topic or any specific command-line option, or you can get a dump of all available help text. The manual continues to contain a greater level of detail and more examples.

  - Bug Fixes

    - Some characters were not correctly translated from PDF doc encoding to Unicode.

    - When splitting or combining pages, ensure that all output files have a PDF version greater than or equal to the maximum version of all the input files.

10.5.0: December 21, 2021

  - Packaging changes

    - Pre-built documentation is no longer distributed with the source distribution. The AppImage and Windows binary distributions still contain embedded documentation, and a separate `doc` distribution file is available from the qpdf release site. Documentation is now available at https://qpdf.readthedocs.io for every major/minor version starting with version 10.5. Please see Packaging Documentation for details on how packagers should handle documentation.

    - The documentation sources have been switched from docbook to reStructuredText processed with Sphinx. This will break previous documentation links. A redirect is in place on the main website. A top-to-bottom review of the documentation is planned for an upcoming release.

  - Library Enhancements

    - Since qpdf version 8, using object accessor methods on an instance of `QPDFObjectHandle` may create warnings if the object is not of the expected type. These warnings now have an error code of `qpdf_e_object` instead of `qpdf_e_damaged_pdf`. Also, comments have been added to `QPDFObjectHandle.hh` to explain in more detail what the behavior is. See Object Accessor Methods for a more in-depth discussion.

    - Add `Pl_Buffer::getMallocBuffer()` to initialize a buffer allocated with `malloc()` for better cross-language interoperability.

  - C API Enhancements

    - Many thanks to M. Holger whose contributions have heavily influenced these C API enhancements. His several suggestions, pull requests, questions, and critical reading of documentation and comments have resulted in significant usability improvements to the C API.

    - Overhaul error handling for the object handle functions C API. Some rare error conditions that would previously have caused a crash are now trapped and reported, and the functions that generate them return fallback values. See comments in the `ERROR HANDLING` section of `include/qpdf/qpdf-c.h` for details. In particular, exceptions thrown by the underlying C++ code when calling object accessors are caught and converted into errors. The errors can be checked by calling `qpdf_has_error`. Use `qpdf_silence_errors` to prevent the error from being written to stderr.

    - Add `qpdf_get_last_string_length` to the C API to get the length of the last string that was returned. This is needed to handle strings that contain embedded null characters.

    - Add `qpdf_oh_is_initialized` and `qpdf_oh_new_uninitialized` to the C API to make it possible to work with uninitialized objects.

    - Add `qpdf_oh_new_object` to the C API. This allows you to clone an object handle.

    - Add `qpdf_get_object_by_id`, `qpdf_make_indirect_object`, and `qpdf_replace_object`, exposing the corresponding methods in `QPDF` and `QPDFObjectHandle`.

    - Add several functions for working with pages. See `PAGE FUNCTIONS` in `include/qpdf/qpdf-c.h` for details.

    - Add several functions for working with streams. See `STREAM FUNCTIONS` in `include/qpdf/qpdf-c.h` for details.

    - Add `qpdf_oh_get_type_code` and `qpdf_oh_get_type_name`.

    - Add `qpdf_oh_get_binary_string_value` and `qpdf_oh_new_binary_string` for making it easier to deal with strings that contain embedded null characters.

10.4.0: November 16, 2021

  - Handling of Weak Cryptography Algorithms

    - From the qpdf CLI, the `--allow-weak-crypto` is now required to suppress a warning when explicitly creating PDF files using RC4 encryption. While qpdf will always retain the ability to read and write such files, doing so will require explicit acknowledgment moving forward. For qpdf 10.4, this change only affects the command-line tool. Starting in qpdf 11, there will be small API changes to require explicit acknowledgment in those cases as well. For additional information, see Weak Cryptography.

  - Bug Fixes

    - Fix potential bounds error when handling shell completion that could occur when given bogus input.

    - Properly handle overlay/underlay on completely empty pages (with no resource dictionary).

    - Fix crash that could occur under certain conditions when using `--pages` with files that had form fields.

  - Library Enhancements

    - Make `QPDF::findPage` functions public.

    - Add methods to `Pl_Flate` to be able to receive warnings on certain recoverable conditions.

    - Add an extra check to the library to detect when foreign objects are inserted directly (instead of using `QPDF::copyForeignObject`) at the time of insertion rather than when the file is written. Catching the error sooner makes it much easier to locate the incorrect code.

  - CLI Enhancements

    - Improve diagnostics around parsing `--pages` command-line options

  - Packaging Changes

    - The Windows binary distribution is now built with crypto provided by OpenSSL 3.0.

10.3.2: May 8, 2021

  - Bug Fixes

    - When generating a file while preserving object streams, unreferenced objects are correctly removed unless `--preserve-unreferenced` is specified.

  - Library Enhancements

    - When adding a page that already exists, make a shallow copy instead of throwing an exception. This makes the library behavior consistent with the CLI behavior. See `ChangeLog` for additional notes.

10.3.1: March 11, 2021

  - Bug Fixes

    - Form field copying failed on files where /DR was a direct object in the document-level form dictionary.

10.3.0: March 4, 2021

  - Bug Fixes

    - The code for handling form fields when copying pages from 10.2.0 was not quite right and didn’t work in a number of situations, such as when the same page was copied multiple times or when there were conflicting resource or field names across multiple copies. The 10.3.0 code has been much more thoroughly tested with more complex cases and with a multitude of readers and should be much closer to correct. The 10.2.0 code worked well enough for page splitting or for copying pages with form fields into documents that didn’t already have them but was still not quite correct in handling of field-level resources.

    - When `QPDF::replaceObject` or `QPDF::swapObjects` is called, existing `QPDFObjectHandle` instances no longer point to the old objects. The next time they are accessed, they automatically notice the change to the underlying object and update themselves. This resolves a very longstanding source of confusion, albeit in a very rarely used method call.

    - Fix form field handling code to look for default appearances, quadding, and default resources in the right places. The code was not looking for things in the document-level interactive form dictionary that it was supposed to be finding there. This required adding a few new methods to `QPDFFormFieldObjectHelper`.

  - Library Enhancements

    - Reworked the code that handles copying annotations and form fields during page operations. There were additional methods added to the public API from 10.2.0 and a one deprecation of a method added in 10.2.0. The majority of the API changes are in methods most people would never call and that will hopefully be superseded by higher-level interfaces for handling page copies. Please see the `ChangeLog` file for details.

    - The method `QPDF::numWarnings` was added so that you can tell whether any warnings happened during a specific block of code.

10.2.0: February 23, 2021

  - CLI Behavior Changes

    - Operations that work on combining pages are much better about protecting form fields. In particular, `--split-pages` and `--pages` now preserve interaction form functionality by copying the relevant form field information from the original files. Additionally, if you use `--pages` to select only some pages from the original input file, unused form fields are removed, which prevents lots of unused annotations from being retained.

    - By default, qpdf no longer allows creation of encrypted PDF files whose user password is non-empty and owner password is empty when a 256-bit key is in use. The `--allow-insecure` option, specified inside the `--encrypt` options, allows creation of such files. Behavior changes in the CLI are avoided when possible, but an exception was made here because this is security-related. qpdf must always allow creation of weird files for testing purposes, but it should not default to letting users unknowingly create insecure files.

  - Library Behavior Changes

    - Note: the changes in this section cause differences in output in some cases. These differences change the syntax of the PDF but do not change the semantics (meaning). I make a strong effort to avoid gratuitous changes in qpdf’s output so that qpdf changes don’t break people’s tests. In this case, the changes significantly improve the readability of the generated PDF and don’t affect any output that’s generated by simple transformation. If you are annoyed by having to update test files, please rest assured that changes like this have been and will continue to be rare events.

    - `QPDFObjectHandle::newUnicodeString` now uses whichever of ASCII, PDFDocEncoding, of UTF-16 is sufficient to encode all the characters in the string. This reduces needless encoding in UTF-16 of strings that can be encoded in ASCII. This change may cause qpdf to generate different output than before when form field values are set using `QPDFFormFieldObjectHelper` but does not change the meaning of the output.

    - The code that places form XObjects and also the code that flattens rotations trim trailing zeroes from real numbers that they calculate. This causes slight (but semantically equivalent) differences in generated appearance streams and form XObject invocations in overlay/underlay code or in user code that calls the methods that place form XObjects on a page.

  - CLI Enhancements

    - Add new command line options for listing, saving, adding, removing, and and copying file attachments. See Embedded Files/Attachments for details.

    - Page splitting and merging operations, as well as `--flatten-rotation`, are better behaved with respect to annotations and interactive form fields. In most cases, interactive form field functionality and proper formatting and functionality of annotations is preserved by these operations. There are still some cases that aren’t perfect, such as when functionality of annotations depends on document-level data that qpdf doesn’t yet understand or when there are problems with referential integrity among form fields and annotations (e.g., when a single form field object or its associated annotations are shared across multiple pages, a case that is out of spec but that works in most viewers anyway).

    - The option `--password-file=filename` can now be used to read the decryption password from a file. You can use `-` as the file name to read the password from standard input. This is an easier/more obvious way to read passwords from files or standard input than using `@file` for this purpose.

    - Add some information about attachments to the JSON output, and added `attachments` as an additional JSON key. The information included here is limited to the preferred name and content stream and a reference to the file spec object. This is enough detail for clients to avoid the hassle of navigating a name tree and provides what is needed for basic enumeration and extraction of attachments. More detailed information can be obtained by following the reference to the file spec object.

    - Add numeric option to `--collate`. If `--collate=n` is given, take pages in groups of `n` from the given files.

    - It is now valid to provide `--rotate=0` to clear rotation from a page.

  - Library Enhancements

    - This release includes numerous additions to the API. Not all changes are listed here. Please see the `ChangeLog` file in the source distribution for a comprehensive list. Highlights appear below.

    - Add `QPDFObjectHandle::ditems()` and `QPDFObjectHandle::aitems()` that enable C++-style iteration, including range-for iteration, over dictionary and array QPDFObjectHandles. See comments in `include/qpdf/QPDFObjectHandle.hh` and `examples/pdf-name-number-tree.cc` for details.

    - Add `QPDFObjectHandle::copyStream` for making a copy of a stream within the same `QPDF` instance.

    - Add new helper classes for supporting file attachments, also known as embedded files. New classes are `QPDFEmbeddedFileDocumentHelper`, `QPDFFileSpecObjectHelper`, and `QPDFEFStreamObjectHelper`. See their respective headers for details and `examples/pdf-attach-file.cc` for an example.

    - Add a version of `QPDFObjectHandle::parse` that takes a `QPDF` pointer as context so that it can parse strings containing indirect object references. This is illustrated in `examples/pdf-attach-file.cc`.

    - Re-implement `QPDFNameTreeObjectHelper` and `QPDFNumberTreeObjectHelper` to be more efficient, add an iterator-based API, give them the capability to repair broken trees, and create methods for modifying the trees. With this change, qpdf has a robust read/write implementation of name and number trees.

    - Add new versions of `QPDFObjectHandle::replaceStreamData` that take `std::function` objects for cases when you need something between a static string and a full-fledged StreamDataProvider. Using this with `QUtil::file_provider` is a very easy way to create a stream from the contents of a file.

    - The `QPDFMatrix` class, formerly a private, internal class, has been added to the public API. See `include/qpdf/QPDFMatrix.hh` for details. This class is for working with transformation matrices. Some methods in `QPDFPageObjectHelper` make use of this to make information about transformation matrices available. For an example, see `examples/pdf-overlay-page.cc`.

    - Several new methods were added to `QPDFAcroFormDocumentHelper` for adding, removing, getting information about, and enumerating form fields.

    - Add method `QPDFAcroFormDocumentHelper::transformAnnotations`, which applies a transformation to each annotation on a page.

    - Add `QPDFPageObjectHelper::copyAnnotations`, which copies annotations and, if applicable, associated form fields, from one page to another, possibly transforming the rectangles.

  - Build Changes

    - A C++-14 compiler is now required to build qpdf. There is no intention to require anything newer than that for a while. C++-14 includes modest enhancements to C++-11 and appears to be supported about as widely as C++-11.

  - Bug Fixes

    - The `--flatten-rotation` option applies transformations to any annotations that may be on the page.

    - If a form XObject lacks a resources dictionary, consider any names in that form XObject to be referenced from the containing page. This is compliant with older PDF versions. Also detect if any form XObjects have any unresolved names and, if so, don’t remove unreferenced resources from them or from the page that contains them. Unfortunately this has the side effect of preventing removal of unreferenced resources in some cases where names appear that don’t refer to resources, such as with tagged PDF. This is a bit of a corner case that is not likely to cause a significant problem in practice, but the only side effect would be lack of removal of shared resources. A future version of qpdf may be more sophisticated in its detection of names that refer to resources.

    - Properly handle strings if they appear in inline image dictionaries while externalizing inline images.

10.1.0: January 5, 2021

  - CLI Enhancements

    - Add `--flatten-rotation` command-line option, which causes all pages that are rotated using parameters in the page’s dictionary to instead be identically rotated in the page’s contents. The change is not user-visible for compliant PDF readers but can be used to work around broken PDF applications that don’t properly handle page rotation.

  - Library Enhancements

    - Support for user-provided (pluggable, modular) stream filters. It is now possible to derive a class from `QPDFStreamFilter` and register it with `QPDF` so that regular library methods, including those used by `QPDFWriter`, can decode streams with filters not directly supported by the library. The example `examples/pdf-custom-filter.cc` illustrates how to use this capability.

    - Add methods to `QPDFPageObjectHelper` to iterate through XObjects on a page or form XObjects, possibly recursing into nested form XObjects: `forEachXObject`, `ForEachImage`, `forEachFormXObject`.

    - Enhance several methods in `QPDFPageObjectHelper` to work with form XObjects as well as pages, as noted in comments. See `ChangeLog` for a full list.

    - Rename some functions in `QPDFPageObjectHelper`, while keeping old names for compatibility:

      - `getPageImages` to `getImages`

      - `filterPageContents` to `filterContents`

      - `pipePageContents` to `pipeContents`

      - `parsePageContents` to `parseContents`

    - Add method `QPDFPageObjectHelper::getFormXObjects` to return a map of form XObjects directly on a page or form XObject

    - Add new helper methods to `QPDFObjectHandle`: `isFormXObject`, `isImage`

    - Add the optional `allow_streams` parameter `QPDFObjectHandle::makeDirect`. When `QPDFObjectHandle::makeDirect` is called in this way, it preserves references to streams rather than throwing an exception.

    - Add `QPDFObjectHandle::setFilterOnWrite` method. Calling this on a stream prevents `QPDFWriter` from attempting to uncompress, recompress, or otherwise filter a stream even if it could. Developers can use this to protect streams that are optimized should be protected from `QPDFWriter`’s default behavior for any other reason.

    - Add `ostream` `<<` operator for `QPDFObjGen`. This is useful to have for debugging.

    - Add method `QPDFPageObjectHelper::flattenRotation`, which replaces a page’s `/Rotate` keyword by rotating the page within the content stream and altering the page’s bounding boxes so the rendering is the same. This can be used to work around buggy PDF readers that can’t properly handle page rotation.

  - C API Enhancements

    - Add several new functions to the C API for working with objects. These are wrappers around many of the methods in `QPDFObjectHandle`. Their inclusion adds considerable new capability to the C API.

    - Add `qpdf_register_progress_reporter` to the C API, corresponding to `QPDFWriter::registerProgressReporter`.

  - Performance Enhancements

    - Improve steps `QPDFWriter` takes to prepare a `QPDF` object for writing, resulting in about an 8% improvement in write performance while allowing indirect objects to appear in `/DecodeParms`.

    - When extracting pages, the qpdf CLI only removes unreferenced resources from the pages that are being kept, resulting in a significant performance improvement when extracting small numbers of pages from large, complex documents.

  - Bug Fixes

    - `QPDFPageObjectHelper::externalizeInlineImages` was not externalizing images referenced from form XObjects that appeared on the page.

    - `QPDFObjectHandle::filterPageContents` was broken for pages with multiple content streams.

    - Tweak zsh completion code to behave a little better with respect to path completion.

10.0.4: November 21, 2020

  - Bug Fixes

    - Fix a handful of integer overflows. This includes cases found by fuzzing as well as having qpdf not do range checking on unused values in the xref stream.

10.0.3: October 31, 2020

  - Bug Fixes

    - The fix to the bug involving copying streams with indirect filters was incorrect and introduced a new, more serious bug. The original bug has been fixed correctly, as has the bug introduced in 10.0.2.

10.0.2: October 27, 2020

  - Bug Fixes

    - When concatenating content streams, as with `--coalesce-contents`, there were cases in which qpdf would merge two lexical tokens together, creating invalid results. A newline is now inserted between merged content streams if one is not already present.

    - Fix an internal error that could occur when copying foreign streams whose stream data had been replaced using a stream data provider if those streams had indirect filters or decode parameters. This is a rare corner case.

    - Ensure that the caller’s locale settings do not change the results of numeric conversions performed internally by the qpdf library. Note that the problem here could only be caused when the qpdf library was used programmatically. Using the qpdf CLI already ignored the user’s locale for numeric conversion.

    - Fix several instances in which warnings were not suppressed in spite of `--no-warn` and/or errors or warnings were written to standard output rather than standard error.

    - Fixed a memory leak that could occur under specific circumstances when `--object-streams=generate` was used.

    - Fix various integer overflows and similar conditions found by the OSS-Fuzz project.

  - Enhancements

    - New option `--warning-exit-0` causes qpdf to exit with a status of `0` rather than `3` if there are warnings but no errors. Combine with `--no-warn` to completely ignore warnings.

    - Performance improvements have been made to `QPDF::processMemoryFile`.

    - The OpenSSL crypto provider produces more detailed error messages.

  - Build Changes

    - The option `--disable-rpath` is now supported by qpdf’s ./configure script. Some distributions’ packaging standards recommended the use of this option.

    - Selection of a printf format string for `long long` has been moved from `ifdefs` to an autoconf test. If you are using your own build system, you will need to provide a value for `LL_FMT` in `libqpdf/qpdf/qpdf-config.h`, which would typically be `"%lld"` or, for some Windows compilers, `"%I64d"`.

    - Several improvements were made to build-time configuration of the OpenSSL crypto provider.

    - A nearly stand-alone Linux binary zip file is now included with the qpdf release. This is built on an older (but supported) Ubuntu LTS release, but would work on most reasonably recent Linux distributions. It contains only the executables and required shared libraries that would not be present on a minimal system. It can be used for including qpdf in a minimal environment, such as a docker container. The zip file is also known to work as a layer in AWS Lambda.

    - QPDF’s automated build has been migrated from Azure Pipelines to GitHub Actions.

  - Windows-specific Changes

    - The Windows executables distributed with qpdf releases now use the OpenSSL crypto provider by default. The native crypto provider is also compiled in and can be selected at runtime with the `QPDF_CRYPTO_PROVIDER` environment variable.

    - Improvements have been made to how a cryptographic provider is obtained in the native Windows crypto implementation. However mostly this is shadowed by OpenSSL being used by default.

10.0.1: April 9, 2020

  - Bug Fixes

    - 10.0.0 introduced a bug in which calling `QPDFObjectHandle::getStreamData` on a stream that can’t be filtered was returning the raw data instead of throwing an exception. This is now fixed.

    - Fix a bug that was preventing qpdf from linking with some versions of clang on some platforms.

  - Enhancements

    - Improve the `pdf-invert-images` example to avoid having to load all the images into RAM at the same time.

10.0.0: April 6, 2020

  - Performance Enhancements

    - The qpdf library and executable should run much faster in this version than in the last several releases. Several internal library optimizations have been made, and there has been improved behavior on page splitting as well. This version of qpdf should outperform any of the 8.x or 9.x versions.

  - Incompatible API (source-level) Changes (minor)

    - The `QUtil::srandom` method was removed. It didn’t do anything unless insecure random numbers were compiled in, and they have been off by default for a long time. If you were calling it, just remove the call since it wasn’t doing anything anyway.

  - Build/Packaging Changes

    - Add a `openssl` crypto provider, which is implemented with OpenSSL and also works with BoringSSL. Thanks to Dean Scarff for this contribution. If you maintain qpdf for a distribution, pay special attention to make sure that you are including support for the crypto providers you want. Package maintainers will have to weigh the advantages of allowing users to pick a crypto provider at runtime against the disadvantages of adding more dependencies to qpdf.

    - Allow qpdf to built on stripped down systems whose C/C++ libraries lack the `wchar_t` type. Search for `wchar_t` in qpdf’s README.md for details. This should be very rare, but it is known to be helpful in some embedded environments.

  - CLI Enhancements

    - Add `objectinfo` key to the JSON output. This will be a place to put computed metadata or other information about PDF objects that are not immediately evident in other ways or that seem useful for some other reason. In this version, information is provided about each object indicating whether it is a stream and, if so, what its length and filters are. Without this, it was not possible to tell conclusively from the JSON output alone whether or not an object was a stream. Run qpdf --json-help for details.

    - Add new option `--remove-unreferenced-resources` which takes `auto`, `yes`, or `no` as arguments. The new `auto` mode, which is the default, performs a fast heuristic over a PDF file when splitting pages to determine whether the expensive process of finding and removing unreferenced resources is likely to be of benefit. For most files, this new default will result in a significant performance improvement for splitting pages.

    - The `--preserve-unreferenced-resources` is now just a synonym for `--remove-unreferenced-resources=no`.

    - If the `QPDF_EXECUTABLE` environment variable is set when invoking qpdf --bash-completion or qpdf --zsh-completion, the completion command that it outputs will refer to qpdf using the value of that variable rather than what qpdf determines its executable path to be. This can be useful when wrapping qpdf with a script, working with a version in the source tree, using an AppImage, or other situations where there is some indirection.

  - Library Enhancements

    - Random number generation is now delegated to the crypto provider. The old behavior is still used by the native crypto provider. It is still possible to provide your own random number generator.

    - Add a new version of `QPDFObjectHandle::StreamDataProvider::provideStreamData` that accepts the `suppress_warnings` and `will_retry` options and allows a success code to be returned. This makes it possible to implement a `StreamDataProvider` that calls `pipeStreamData` on another stream and to pass the response back to the caller, which enables better error handling on those proxied streams.

    - Update `QPDFObjectHandle::pipeStreamData` to return an overall success code that goes beyond whether or not filtered data was written successfully. This allows better error handling of cases that were not filtering errors. You have to call this explicitly. Methods in previously existing APIs have the same semantics as before.

    - The `QPDFPageObjectHelper::placeFormXObject` method now allows separate control over whether it should be willing to shrink or expand objects to fit them better into the destination rectangle. The previous behavior was that shrinking was allowed but expansion was not. The previous behavior is still the default.

    - When calling the C API, any non-zero value passed to a boolean parameter is treated as `TRUE`. Previously only the value `1` was accepted. This makes the C API behave more like most C interfaces and is known to improve compatibility with some Windows environments that dynamically load the DLL and call functions from it.

    - Add `QPDFObjectHandle::unsafeShallowCopy` for copying only top-level dictionary keys or array items. This is unsafe because it creates a situation in which changing a lower-level item in one object may also change it in another object, but for cases in which you know you are only inserting or replacing top-level items, it is much faster than `QPDFObjectHandle::shallowCopy`.

    - Add `QPDFObjectHandle::filterAsContents`, which filter’s a stream’s data as a content stream. This is useful for parsing the contents for form XObjects in the same way as parsing page content streams.

  - Bug Fixes

    - When detecting and removing unreferenced resources during page splitting, traverse into form XObjects and handle their resources dictionaries as well.

    - The same error recovery is applied to streams in other than the primary input file when merging or splitting pages.

9.1.1: January 26, 2020

  - Build/Packaging Changes

    - The fix-qdf program was converted from perl to C++. As such, qpdf no longer has a runtime dependency on perl.

  - Library Enhancements

    - Added new helper routine `QUtil::call_main_from_wmain` which converts `wchar_t` arguments to UTF-8 encoded strings. This is useful for qpdf because library methods expect file names to be UTF-8 encoded, even on Windows

    - Added new `QUtil::read_lines_from_file` methods that take `FILE*` arguments and that allow preservation of end-of-line characters. This also fixes a bug where `QUtil::read_lines_from_file` wouldn’t work properly with Unicode filenames.

  - CLI Enhancements

    - Added options `--is-encrypted` and `--requires-password` for testing whether a file is encrypted or requires a password other than the supplied (or empty) password. These communicate via exit status, making them useful for shell scripts. They also work on encrypted files with unknown passwords.

    - Added `encrypt` key to JSON options. With the exception of the reconstructed user password for older encryption formats, this provides the same information as `--show-encryption` but in a consistent, parseable format. See output of qpdf --json-help for details.

  - Bug Fixes

    - In QDF mode, be sure not to write more than one XRef stream to a file, even when `--preserve-unreferenced` is used. fix-qdf assumes that there is only one XRef stream, and that it appears at the end of the file.

    - When externalizing inline images, properly handle images whose color space is a reference to an object in the page’s resource dictionary.

    - Windows-specific fix for acquiring crypt context with a new keyset.

9.1.0: November 17, 2019

  - Build Changes

    - A C++-11 compiler is now required to build qpdf.

    - A new crypto provider that uses gnutls for crypto functions is now available and can be enabled at build time. See Crypto Providers for more information about crypto providers and Build-time Crypto Selection for specific information about the build.

  - Library Enhancements

    - Incorporate contribution from Masamichi Hosoda to properly handle signature dictionaries by not including them in object streams, formatting the `Contents` key has a hexadecimal string, and excluding the `/Contents` key from encryption and decryption.

    - Incorporate contribution from Masamichi Hosoda to provide new API calls for getting file-level information about input and output files, enabling certain operations on the files at the file level rather than the object level. New methods include `QPDF::getXRefTable()`, `QPDFObjectHandle::getParsedOffset()`, `QPDFWriter::getRenumberedObjGen(QPDFObjGen)`, and `QPDFWriter::getWrittenXRefTable()`.

    - Support build-time and runtime selectable crypto providers. This includes the addition of new classes `QPDFCryptoProvider` and `QPDFCryptoImpl` and the recognition of the `QPDF_CRYPTO_PROVIDER` environment variable. Crypto providers are described in depth in Crypto Providers.

  - CLI Enhancements

    - Addition of the `--show-crypto` option in support of selectable crypto providers, as described in Crypto Providers.

    - Allow `:even` or `:odd` to be appended to numeric ranges for specification of the even or odd pages from among the pages specified in the range.

    - Fix shell wildcard expansion behavior (`*` and `?`) of the qpdf.exe as built my MSVC.

9.0.2: October 12, 2019

  - Bug Fix

    - Fix the name of the temporary file used by `--replace-input` so that it doesn’t require path splitting and works with paths include directories.

9.0.1: September 20, 2019

  - Bug Fixes/Enhancements

    - Fix some build and test issues on big-endian systems and compilers with characters that are unsigned by default. The problems were in build and test only. There were no actual bugs in the qpdf library itself relating to endianness or unsigned characters.

    - When a dictionary has a duplicated key, report this with a warning. The behavior of the library in this case is unchanged, but the error condition is no longer silently ignored.

    - When a form field’s display rectangle is erroneously specified with inverted coordinates, detect and correct this situation. This avoids some form fields from being flipped when flattening annotations on files with this condition.

9.0.0: August 31, 2019

  - Incompatible API (source-level) Changes (minor)

    - The method `QUtil::strcasecmp` has been renamed to `QUtil::str_compare_nocase`. This incompatible change is necessary to enable qpdf to build on platforms that define `strcasecmp` as a macro.

    - The `QPDF::copyForeignObject` method had an overloaded version that took a boolean parameter that was not used. If you were using this version, just omit the extra parameter.

    - There was a version `QPDFTokenizer::expectInlineImage` that took no arguments. This version has been removed since it caused the tokenizer to return incorrect inline images. A new version was added some time ago that produces correct output. This is a very low level method that doesn’t make sense to call outside of qpdf’s lexical engine. There are higher level methods for tokenizing content streams.

    - Change `QPDFOutlineDocumentHelper::getTopLevelOutlines` and `QPDFOutlineObjectHelper::getKids` to return a `std::vector` instead of a `std::list` of `QPDFOutlineObjectHelper` objects.

    - Remove method `QPDFTokenizer::allowPoundAnywhereInName`. This function would allow creation of name tokens whose value would change when unparsed, which is never the correct behavior.

  - CLI Enhancements

    - The `--replace-input` option may be given in place of an output file name. This causes qpdf to overwrite the input file with the output. See the description of `--replace-input` for more details.

    - The `--recompress-flate` instructs qpdf to recompress streams that are already compressed with `/FlateDecode`. Useful with `--compression-level`.

    - The `--compression-level=level` sets the zlib compression level used for any streams compressed by `/FlateDecode`. Most effective when combined with `--recompress-flate`.

  - Library Enhancements

    - A new namespace `QIntC`, provided by `qpdf/QIntC.hh`, provides safe conversion methods between different integer types. These conversion methods do range checking to ensure that the cast can be performed with no loss of information. Every use of `static_cast` in the library was inspected to see if it could use one of these safe converters instead. See Casting Policy for additional details.

    - Method `QPDF::anyWarnings` tells whether there have been any warnings without clearing the list of warnings.

    - Method `QPDF::closeInputSource` closes or otherwise releases the input source. This enables the input file to be deleted or renamed.

    - New methods have been added to `QUtil` for converting back and forth between strings and unsigned integers: `uint_to_string`, `uint_to_string_base`, `string_to_uint`, and `string_to_ull`.

    - New methods have been added to `QPDFObjectHandle` that return the value of `Integer` objects as `int` or `unsigned int` with range checking and sensible fallback values, and a new method was added to return an unsigned value. This makes it easier to write code that is safe from unintentional data loss. Functions: `getUIntValue`, `getIntValueAsInt`, `getUIntValueAsUInt`.

    - When parsing content streams with `QPDFObjectHandle::ParserCallbacks`, in place of the method `handleObject(QPDFObjectHandle)`, the developer may override `handleObject(QPDFObjectHandle, size_t offset, size_t length)`. If this method is defined, it will be invoked with the object along with its offset and length within the overall contents being parsed. Intervening spaces and comments are not included in offset and length. Additionally, a new method `contentSize(size_t)` may be implemented. If present, it will be called prior to the first call to `handleObject` with the total size in bytes of the combined contents.

    - New methods `QPDF::userPasswordMatched` and `QPDF::ownerPasswordMatched` have been added to enable a caller to determine whether the supplied password was the user password, the owner password, or both. This information is also displayed by qpdf --show-encryption and qpdf --check.

    - Static method `Pl_Flate::setCompressionLevel` can be called to set the zlib compression level globally used by all instances of Pl_Flate in deflate mode.

    - The method `QPDFWriter::setRecompressFlate` can be called to tell `QPDFWriter` to uncompress and recompress streams already compressed with `/FlateDecode`.

    - The underlying implementation of QPDF arrays has been enhanced to be much more memory efficient when dealing with arrays with lots of nulls. This enables qpdf to use drastically less memory for certain types of files.

    - When traversing the pages tree, if nodes are encountered with invalid types, the types are fixed, and a warning is issued.

    - A new helper method `QUtil::read_file_into_memory` was added.

    - All conditions previously reported by `QPDF::checkLinearization()` as errors are now presented as warnings.

    - Name tokens containing the `#` character not preceded by two hexadecimal digits, which is invalid in PDF 1.2 and above, are properly handled by the library: a warning is generated, and the name token is properly preserved, even if invalid, in the output. See `ChangeLog` for a more complete description of this change.

  - Bug Fixes

    - A small handful of memory issues, assertion failures, and unhandled exceptions that could occur on badly mangled input files have been fixed. Most of these problems were found by Google’s OSS-Fuzz project.

    - When qpdf --check or qpdf --check-linearization encounters a file with linearization warnings but not errors, it now properly exits with exit code 3 instead of 2.

    - The `--completion-bash` and `--completion-zsh` options now work properly when qpdf is invoked as an AppImage.

    - Calling `QPDFWriter::set*EncryptionParameters` on a `QPDFWriter` object whose output filename has not yet been set no longer produces a segmentation fault.

    - When reading encrypted files, follow the spec more closely regarding encryption key length. This allows qpdf to open encrypted files in most cases when they have invalid or missing /Length keys in the encryption dictionary.

  - Build Changes

    - On platforms that support it, qpdf now builds with `-fvisibility=hidden`. If you build qpdf with your own build system, this is now safe to use. This prevents methods that are not part of the public API from being exported by the shared library, and makes qpdf’s ELF shared libraries (used on Linux, MacOS, and most other UNIX flavors) behave more like the Windows DLL. Since the DLL already behaves in much this way, it is unlikely that there are any methods that were accidentally not exported. However, with ELF shared libraries, typeinfo for some classes has to be explicitly exported. If there are problems in dynamically linked code catching exceptions or subclassing, this could be the reason. If you see this, please report a bug at https://github.com/qpdf/qpdf/issues/.

    - QPDF is now compiled with integer conversion and sign conversion warnings enabled. Numerous changes were made to the library to make this safe.

    - QPDF’s make install target explicitly specifies the mode to use when installing files instead of relying the user’s umask. It was previously doing this for some files but not others.

    - If pkg-config is available, use it to locate `libjpeg` and `zlib` dependencies, falling back on old behavior if unsuccessful.

  - Other Notes

    - QPDF has been fully integrated into Google’s OSS-Fuzz project. This project exercises code with randomly mutated inputs and is great for discovering hidden security crashes and security issues. Several bugs found by oss-fuzz have already been fixed in qpdf.

8.4.2: May 18, 2019

  This release has just one change: correction of a buffer overrun in the Windows code used to open files. Windows users should take this update. There are no code changes that affect non-Windows releases.

8.4.1: April 27, 2019

  - Enhancements

    - When qpdf --version is run, it will detect if the qpdf CLI was built with a different version of qpdf than the library, which may indicate a problem with the installation.

    - New option `--remove-page-labels` will remove page labels before generating output. This used to happen if you ran qpdf --empty --pages .. --, but the behavior changed in qpdf 8.3.0. This option enables people who were relying on the old behavior to get it again.

    - New option `--keep-files-open-threshold=count` can be used to override number of files that qpdf will use to trigger the behavior of not keeping all files open when merging files. This may be necessary if your system allows fewer than the default value of 200 files to be open at the same time.

  - Bug Fixes

    - Handle Unicode characters in filenames on Windows. The changes to support Unicode on the CLI in Windows broke Unicode filenames for Windows.

    - Slightly tighten logic that determines whether an object is a page. This should resolve problems in some rare files where some non-page objects were passing qpdf’s test for whether something was a page, thus causing them to be erroneously lost during page splitting operations.

    - Revert change that included preservation of outlines (bookmarks) in `--split-pages`. The way it was implemented in 8.3.0 and 8.4.0 caused a very significant degradation of performance for splitting certain files. A future release of qpdf may re-introduce the behavior in a more performant and also more correct fashion.

    - In JSON mode, add missing leading 0 to decimal values between -1 and 1 even if not present in the input. The JSON specification requires the leading 0. The PDF specification does not.

8.4.0: February 1, 2019

  - Command-line Enhancements

    - Non-compatible CLI change: The qpdf command-line tool interprets passwords given at the command-line differently from previous releases when the passwords contain non-ASCII characters. In some cases, the behavior differs from previous releases. For a discussion of the current behavior, please see Unicode Passwords. The incompatibilities are as follows:

      - On Windows, qpdf now receives all command-line options as Unicode strings if it can figure out the appropriate compile/link options. This is enabled at least for MSVC and mingw builds. That means that if non-ASCII strings are passed to the qpdf CLI in Windows, qpdf will now correctly receive them. In the past, they would have either been encoded as Windows code page 1252 (also known as “Windows ANSI” or as something unintelligible. In almost all cases, qpdf is able to properly interpret Unicode arguments now, whereas in the past, it would almost never interpret them properly. The result is that non-ASCII passwords given to the qpdf CLI on Windows now have a much greater chance of creating PDF files that can be opened by a variety of readers. In the past, usually files encrypted from the Windows CLI using non-ASCII passwords would not be readable by most viewers. Note that the current version of qpdf is able to decrypt files that it previously created using the previously supplied password.

      - The PDF specification requires passwords to be encoded as UTF-8 for 256-bit encryption and with PDF Doc encoding for 40-bit or 128-bit encryption. Older versions of qpdf left it up to the user to provide passwords with the correct encoding. The qpdf CLI now detects when a password is given with UTF-8 encoding and automatically transcodes it to what the PDF spec requires. While this is almost always the correct behavior, it is possible to override the behavior if there is some reason to do so. This is discussed in more depth in Unicode Passwords.

    - New options `--externalize-inline-images`, `--ii-min-bytes`, and `--keep-inline-images` control qpdf’s handling of inline images and possible conversion of them to regular images. By default, `--optimize-images` now also applies to inline images.

    - Add options `--overlay` and `--underlay` for overlaying or underlaying pages of other files onto output pages. See Overlay and Underlay for details.

    - When opening an encrypted file with a password, if the specified password doesn’t work and the password contains any non-ASCII characters, qpdf will try a number of alternative passwords to try to compensate for possible character encoding errors. This behavior can be suppressed with the `--suppress-password-recovery` option. See Unicode Passwords for a full discussion.

    - Add the `--password-mode` option to fine-tune how qpdf interprets password arguments, especially when they contain non-ASCII characters. See Unicode Passwords for more information.

    - In the `--pages` option, it is now possible to copy the same page more than once from the same file without using the previous workaround of specifying two different paths to the same file.

    - In the `--pages` option, allow use of “.” as a shortcut for the primary input file. That way, you can do qpdf in.pdf --pages . 1-2 -- out.pdf instead of having to repeat `in.pdf` in the command.

    - When encrypting with 128-bit and 256-bit encryption, new encryption options `--assemble`, `--annotate`, `--form`, and `--modify-other` allow more fine-grained granularity in configuring options. Before, the `--modify` option only configured certain predefined groups of permissions.

  - Bug Fixes and Enhancements

    - Potential data-loss bug: Versions of qpdf between 8.1.0 and 8.3.0 had a bug that could cause page splitting and merging operations to drop some font or image resources if the PDF file’s internal structure shared these resource lists across pages and if some but not all of the pages in the output did not reference all the fonts and images. Using the `--preserve-unreferenced-resources` option would work around the incorrect behavior. This bug was the result of a typo in the code and a deficiency in the test suite. The case that triggered the error was known, just not handled properly. This case is now exercised in qpdf’s test suite and properly handled.

    - When optimizing images, detect and refuse to optimize images that can’t be converted to JPEG because of bit depth or color space.

    - Linearization and page manipulation APIs now detect and recover from files that have duplicate Page objects in the pages tree.

    - Using older option `--stream-data=compress` with object streams, object streams and xref streams were not compressed.

    - When the tokenizer returns inline image tokens, delimiters following `ID` and `EI` operators are no longer excluded. This makes it possible to reliably extract the actual image data.

  - Library Enhancements

    - Add method `QPDFPageObjectHelper::externalizeInlineImages` to convert inline images to regular images.

    - Add method `QUtil::possible_repaired_encodings()` to generate a list of strings that represent other ways the given string could have been encoded. This is the method the QPDF CLI uses to generate the strings it tries when recovering incorrectly encoded Unicode passwords.

    - Add new versions of `QPDFWriter::setR{3,4,5,6}EncryptionParameters` that allow more granular setting of permissions bits. See `QPDFWriter.hh` for details.

    - Add new versions of the transcoders from UTF-8 to single-byte coding systems in `QUtil` that report success or failure rather than just substituting a specified unknown character.

    - Add method `QUtil::analyze_encoding()` to determine whether a string has high-bit characters and is appears to be UTF-16 or valid UTF-8 encoding.

    - Add new method `QPDFPageObjectHelper::shallowCopyPage()` to copy a new page that is a “shallow copy” of a page. The resulting object is an indirect object ready to be passed to `QPDFPageDocumentHelper::addPage()` for either the original `QPDF` object or a different one. This is what the qpdf command-line tool uses to copy the same page multiple times from the same file during splitting and merging operations.

    - Add method `QPDF::getUniqueId()`, which returns a unique identifier for the given QPDF object. The identifier will be unique across the life of the application. The returned value can be safely used as a map key.

    - Add method `QPDF::setImmediateCopyFrom`. This further enhances qpdf’s ability to allow a `QPDF` object from which objects are being copied to go out of scope before the destination object is written. If you call this method on a `QPDF` instances, objects copied from this instance will be copied immediately instead of lazily. This option uses more memory but allows the source object to go out of scope before the destination object is written in all cases. See comments in `QPDF.hh` for details.

    - Add method `QPDFPageObjectHelper::getAttribute` for retrieving an attribute from the page dictionary taking inheritance into consideration, and optionally making a copy if your intention is to modify the attribute.

    - Fix long-standing limitation of `QPDFPageObjectHelper::getPageImages` so that it now properly reports images from inherited resources dictionaries, eliminating the need to call `QPDFPageDocumentHelper::pushInheritedAttributesToPage` in this case.

    - Add method `QPDFObjectHandle::getUniqueResourceName` for finding an unused name in a resource dictionary.

    - Add method `QPDFPageObjectHelper::getFormXObjectForPage` for generating a form XObject equivalent to a page. The resulting object can be used in the same file or copied to another file with `copyForeignObject`. This can be useful for implementing underlay, overlay, n-up, thumbnails, or any other functionality requiring replication of pages in other contexts.

    - Add method `QPDFPageObjectHelper::placeFormXObject` for generating content stream text that places a given form XObject on a page, centered and fit within a specified rectangle. This method takes care of computing the proper transformation matrix and may optionally compensate for rotation or scaling of the destination page.

    - Exit codes returned by `QPDFJob::run()` and the C API wrappers are now defined in `qpdf/Constants.h` in the `qpdf_exit_code_e` type so that they are accessible from the C API. They were previously only defined as constants in `qpdf/QPDFJob.hh`.

  - Build Improvements

    - Add new configure option `--enable-avoid-windows-handle`, which causes the preprocessor symbol `AVOID_WINDOWS_HANDLE` to be defined. When defined, qpdf will avoid referencing the Windows `HANDLE` type, which is disallowed with certain versions of the Windows SDK.

    - For Windows builds, attempt to determine what options, if any, have to be passed to the compiler and linker to enable use of `wmain`. This causes the preprocessor symbol `WINDOWS_WMAIN` to be defined. If you do your own builds with other compilers, you can define this symbol to cause `wmain` to be used. This is needed to allow the Windows qpdf command to receive Unicode command-line options.

8.3.0: January 7, 2019

  - Command-line Enhancements

    - Shell completion: you can now use eval $(qpdf --completion-bash) and eval $(qpdf --completion-zsh) to enable shell completion for bash and zsh.

    - Page numbers (also known as page labels) are now preserved when merging and splitting files with the `--pages` and `--split-pages` options.

    - Bookmarks are partially preserved when splitting pages with the `--split-pages` option. Specifically, the outlines dictionary and some supporting metadata are copied into the split files. The result is that all bookmarks from the original file appear, those that point to pages that are preserved work, and those that point to pages that are not preserved don’t do anything. This is an interim step toward proper support for bookmarks in splitting and merging operations.

    - Page collation: add new option `--collate`. When specified, the semantics of `--pages` change from concatenation to collation. See Page Selection for examples and discussion.

    - Generation of information in JSON format, primarily to facilitate use of qpdf from languages other than C++. Add new options `--json`, `--json-key`, and `--json-object` to generate a JSON representation of the PDF file. Run qpdf --json-help to get a description of the JSON format. For more information, see qpdf JSON.

    - The `--generate-appearances` flag will cause qpdf to generate appearances for form fields if the PDF file indicates that form field appearances are out of date. This can happen when PDF forms are filled in by a program that doesn’t know how to regenerate the appearances of the filled-in fields.

    - The `--flatten-annotations` flag can be used to flatten annotations, including form fields. Ordinarily, annotations are drawn separately from the page. Flattening annotations is the process of combining their appearances into the page’s contents. You might want to do this if you are going to rotate or combine pages using a tool that doesn’t understand about annotations. You may also want to use `--generate-appearances` when using this flag since annotations for outdated form fields are not flattened as that would cause loss of information.

    - The `--optimize-images` flag tells qpdf to recompresses every image using DCT (JPEG) compression as long as the image is not already compressed with lossy compression and recompressing the image reduces its size. The additional options `--oi-min-width`, `--oi-min-height`, and `--oi-min-area` prevent recompression of images whose width, height, or pixel area (width × height) are below a specified threshold.

    - The `--show-object` option can now be given as `--show-object=trailer` to show the trailer dictionary.

  - Bug Fixes and Enhancements

    - QPDF now automatically detects and recovers from dangling references. If a PDF file contained an indirect reference to a non-existent object, which is valid, when adding a new object to the file, it was possible for the new object to take the object ID of the dangling reference, thereby causing the dangling reference to point to the new object. This case is now prevented.

    - Fixes to form field setting code: strings are always written in UTF-16 format, and checkboxes and radio buttons are handled properly with respect to synchronization of values and appearance states.

    - The `QPDF::checkLinearization()` no longer causes the program to crash when it detects problems with linearization data. Instead, it issues a normal warning or error.

    - Ordinarily qpdf treats an argument of the form `@file` to mean that command-line options should be read from `file`. Now, if `file` does not exist but `@file` does, qpdf will treat `@file` as a regular option. This makes it possible to work more easily with PDF files whose names happen to start with the `@` character.

  - Library Enhancements

    - Remove the restriction in most cases that the source QPDF object used in a `QPDF::copyForeignObject` call has to stick around until the destination QPDF is written. The exceptional case is when the source stream gets is data using a QPDFObjectHandle::StreamDataProvider. For a more in-depth discussion, see comments around `copyForeignObject` in `QPDF.hh`.

    - Add new method `QPDFWriter::getFinalVersion()`, which returns the PDF version that will ultimately be written to the final file. See comments in `QPDFWriter.hh` for some restrictions on its use.

    - Add several methods for transcoding strings to some of the character sets used in PDF files: `QUtil::utf8_to_ascii`, `QUtil::utf8_to_win_ansi`, `QUtil::utf8_to_mac_roman`, and `QUtil::utf8_to_utf16`. For the single-byte encodings that support only a limited character sets, these methods replace unsupported characters with a specified substitute.

    - Add new methods to `QPDFAnnotationObjectHelper` and `QPDFFormFieldObjectHelper` for querying flags and interpretation of different field types. Define constants in `qpdf/Constants.h` to help with interpretation of flag values.

    - Add new methods `QPDFAcroFormDocumentHelper::generateAppearancesIfNeeded` and `QPDFFormFieldObjectHelper::generateAppearance` for generating appearance streams. See discussion in `QPDFFormFieldObjectHelper.hh` for limitations.

    - Add two new helper functions for dealing with resource dictionaries: `QPDFObjectHandle::getResourceNames()` returns a list of all second-level keys, which correspond to the names of resources, and `QPDFObjectHandle::mergeResources()` merges two resources dictionaries as long as they have non-conflicting keys. These methods are useful for certain types of objects that resolve resources from multiple places, such as form fields.

    - Add methods `QPDFPageDocumentHelper::flattenAnnotations()` and `QPDFAnnotationObjectHelper::getPageContentForAppearance()` for handling low-level details of annotation flattening.

    - Add new helper classes: `QPDFOutlineDocumentHelper`, `QPDFOutlineObjectHelper`, `QPDFPageLabelDocumentHelper`, `QPDFNameTreeObjectHelper`, and `QPDFNumberTreeObjectHelper`.

    - Add method `QPDFObjectHandle::getJSON()` that returns a JSON representation of the object. Call `serialize()` on the result to convert it to a string.

    - Add a simple JSON serializer. This is not a complete or general-purpose JSON library. It allows assembly and serialization of JSON structures with some restrictions, which are described in the header file. This is the serializer used by qpdf’s new JSON representation.

    - Add new `QPDFObjectHandle::Matrix` class along with a few convenience methods for dealing with six-element numerical arrays as matrices.

    - Add new method `QPDFObjectHandle::wrapInArray`, which returns the object itself if it is an array, or an array containing the object otherwise. This is a common construct in PDF. This method prevents you from having to explicitly test whether something is a single element or an array.

  - Build Improvements

    - It is no longer necessary to run autogen.sh to build from a pristine checkout. Automatically generated files are now committed so that it is possible to build on platforms without autoconf directly from a clean checkout of the repository. The configure script detects if the files are out of date when it also determines that the tools are present to regenerate them.

    - Pull requests and the master branch are now built automatically in Azure Pipelines, which is free for open source projects. The build includes Linux, mac, Windows 32-bit and 64-bit with mingw and MSVC, and an AppImage build. Official qpdf releases are now built with Azure Pipelines.

  - Notes for Packagers

    - A new section has been added to the documentation with notes for packagers. Please see Notes for Packagers.

    - The qpdf detects out-of-date automatically generated files. If your packaging system automatically refreshes libtool or autoconf files, it could cause this check to fail. To avoid this problem, pass `--disable-check-autofiles` to configure.

    - If you would like to have qpdf completion enabled automatically, you can install completion files in the distribution’s default location. You can find sample completion files to install in the `completions` directory.

8.2.1: August 18, 2018

  - Command-line Enhancements

    - Add `--keep-files-open=[yn]` to override default determination of whether to keep files open when merging. Please see the discussion of `--keep-files-open` for additional details.

8.2.0: August 16, 2018

  - Command-line Enhancements

    - Add `--no-warn` option to suppress issuing warning messages. If there are any conditions that would have caused warnings to be issued, the exit status is still 3.

  - Bug Fixes and Optimizations

    - Performance fix: optimize page merging operation to avoid unnecessary open/close calls on files being merged. This solves a dramatic slow-down that was observed when merging certain types of files.

    - Optimize how memory was used for the TIFF predictor, drastically improving performance and memory usage for files containing high-resolution images compressed with Flate using the TIFF predictor.

    - Bug fix: end of line characters were not properly handled inside strings in some cases.

    - Bug fix: using `--progress` on very small files could cause an infinite loop.

  - API enhancements

    - Add new class `QPDFSystemError`, derived from `std::runtime_error`, which is now thrown by `QUtil::throw_system_error`. This enables the triggering `errno` value to be retrieved.

    - Add `ClosedFileInputSource::stayOpen` method, enabling a `ClosedFileInputSource` to stay open during manually indicated periods of high activity, thus reducing the overhead of frequent open/close operations.

  - Build Changes

    - For the mingw builds, change the name of the DLL import library from `libqpdf.a` to `libqpdf.dll.a` to more accurately reflect that it is an import library rather than a static library. This potentially clears the way for supporting a static library in the future, though presently, the qpdf Windows build only builds the DLL and executables.

8.1.0: June 23, 2018

  - Usability Improvements

    - When splitting files, qpdf detects fonts and images that the document metadata claims are referenced from a page but are not actually referenced and omits them from the output file. This change can cause a significant reduction in the size of split PDF files for files created by some software packages. In some cases, it can also make page splitting slower. Prior versions of qpdf would believe the document metadata and sometimes include all the images from all the other pages even though the pages were no longer present. In the unlikely event that the old behavior should be desired, or if you have a case where page splitting is very slow, the old behavior (and speed) can be enabled by specifying `--preserve-unreferenced-resources`.

    - When merging multiple PDF files, qpdf no longer leaves all the files open. This makes it possible to merge numbers of files that may exceed the operating system’s limit for the maximum number of open files.

    - The `--rotate` option’s syntax has been extended to make the page range optional. If you specify `--rotate=angle` without specifying a page range, the rotation will be applied to all pages. This can be especially useful for adjusting a PDF created from a multi-page document that was scanned upside down.

    - When merging multiple files, the `--verbose` option now prints information about each file as it operates on that file.

    - When the `--progress` option is specified, qpdf will print a running indicator of its best guess at how far through the writing process it is. Note that, as with all progress meters, it’s an approximation. This option is implemented in a way that makes it useful for software that uses the qpdf library; see API Enhancements below.

  - Bug Fixes

    - Properly decrypt files that use revision 3 of the standard security handler but use 40 bit keys (even though revision 3 supports 128-bit keys).

    - Limit depth of nested data structures to prevent crashes from certain types of malformed (malicious) PDFs.

    - In “newline before endstream” mode, insert the required extra newline before the `endstream` at the end of object streams. This one case was previously omitted.

  - API Enhancements

    - The first round of higher level “helper” interfaces has been introduced. These are designed to provide a more convenient way of interacting with certain document features than using `QPDFObjectHandle` directly. For details on helpers, see Helper Classes. Specific additional interfaces are described below.

    - Add two new document helper classes: `QPDFPageDocumentHelper` for working with pages, and `QPDFAcroFormDocumentHelper` for working with interactive forms. No old methods have been removed, but `QPDFPageDocumentHelper` is now the preferred way to perform operations on pages rather than calling the old methods in `QPDFObjectHandle` and `QPDF` directly. Comments in the header files direct you to the new interfaces. Please see the header files and `ChangeLog` for additional details.

    - Add three new object helper class: `QPDFPageObjectHelper` for pages, `QPDFFormFieldObjectHelper` for interactive form fields, and `QPDFAnnotationObjectHelper` for annotations. All three classes are fairly sparse at the moment, but they have some useful, basic functionality.

    - A new example program `examples/pdf-set-form-values.cc` has been added that illustrates use of the new document and object helpers.

    - The method `QPDFWriter::registerProgressReporter` has been added. This method allows you to register a function that is called by `QPDFWriter` to update your idea of the percentage it thinks it is through writing its output. Client programs can use this to implement reasonably accurate progress meters. The qpdf command line tool uses this to implement its `--progress` option.

    - New methods `QPDFObjectHandle::newUnicodeString` and `QPDFObject::unparseBinary` have been added to allow for more convenient creation of strings that are explicitly encoded using big-endian UTF-16. This is useful for creating strings that appear outside of content streams, such as labels, form fields, outlines, document metadata, etc.

    - A new class `QPDFObjectHandle::Rectangle` has been added to ease working with PDF rectangles, which are just arrays of four numeric values.

8.0.2: March 6, 2018

  - When a loop is detected while following cross reference streams or tables, treat this as damage instead of silently ignoring the previous table. This prevents loss of otherwise recoverable data in some damaged files.

  - Properly handle pages with no contents.

8.0.1: March 4, 2018

  - Disregard data check errors when uncompressing `/FlateDecode` streams. This is consistent with most other PDF readers and allows qpdf to recover data from another class of malformed PDF files.

  - On the command line when specifying page ranges, support preceding a page number by “r” to indicate that it should be counted from the end. For example, the range `r3-r1` would indicate the last three pages of a document.

8.0.0: February 25, 2018

  - Packaging and Distribution Changes

    - QPDF is now distributed as an AppImage in addition to all the other ways it is distributed. The AppImage can be found in the download area with the other packages. Thanks to Kurt Pfeifle and Simon Peter for their contributions.

  - Bug Fixes

    - `QPDFObjectHandle::getUTF8Val` now properly treats non-Unicode strings as encoded with PDF Doc Encoding.

    - Improvements to handling of objects in PDF files that are not of the expected type. In most cases, qpdf will be able to warn for such cases rather than fail with an exception. Previous versions of qpdf would sometimes fail with errors such as “operation for dictionary object attempted on object of wrong type”. This situation should be mostly or entirely eliminated now.

  - Enhancements to the qpdf Command-line Tool. All new options listed here are documented in more detail in Running qpdf.

    - The option `--linearize-pass1=file` has been added for debugging qpdf’s linearization code.

    - The option `--coalesce-contents` can be used to combine content streams of a page whose contents are an array of streams into a single stream.

  - API Enhancements. All new API calls are documented in their respective classes’ header files. There are no non-compatible changes to the API.

    - Add function `qpdf_check_pdf` to the C API. This function does basic checking that is a subset of what qpdf --check performs.

    - Major enhancements to the lexical layer of qpdf. For a complete list of enhancements, please refer to the `ChangeLog` file. Most of the changes result in improvements to qpdf’s ability handle erroneous files. It is also possible for programs to handle whitespace, comments, and inline images as tokens.

    - New API for working with PDF content streams at a lexical level. The new class `QPDFObjectHandle::TokenFilter` allows the developer to provide token handlers. Token filters can be used with several different methods in `QPDFObjectHandle` as well as with a lower-level interface. See comments in `QPDFObjectHandle.hh` as well as the new examples `examples/pdf-filter-tokens.cc` and `examples/pdf-count-strings.cc` for details.

7.1.1: February 4, 2018

  - Bug fix: files whose /ID fields were other than 16 bytes long can now be properly linearized

  - A few compile and link issues have been corrected for some platforms.

7.1.0: January 14, 2018

  - PDF files contain streams that may be compressed with various compression algorithms which, in some cases, may be enhanced by various predictor functions. Previously only the PNG up predictor was supported. In this version, all the PNG predictors as well as the TIFF predictor are supported. This increases the range of files that qpdf is able to handle.

  - QPDF now allows a raw encryption key to be specified in place of a password when opening encrypted files, and will optionally display the encryption key used by a file. This is a non-standard operation, but it can be useful in certain situations. Please see the discussion of `--password-is-hex-key` or the comments around `QPDF::setPasswordIsHexKey` in `QPDF.hh` for additional details.

  - Bug fix: numbers ending with a trailing decimal point are now properly recognized as numbers.

  - Bug fix: when building qpdf from source on some platforms (especially MacOS), the build could get confused by older versions of qpdf installed on the system. This has been corrected.

7.0.0: September 15, 2017

  - Packaging and Distribution Changes

    - QPDF’s primary license is now version 2.0 of the Apache License rather than version 2.0 of the Artistic License. You may still, at your option, consider qpdf to be licensed with version 2.0 of the Artistic license.

    - QPDF no longer has a dependency on the PCRE (Perl-Compatible Regular Expression) library. QPDF now has an added dependency on the JPEG library.

  - Bug Fixes

    - This release contains many bug fixes for various infinite loops, memory leaks, and other memory errors that could be encountered with specially crafted or otherwise erroneous PDF files.

  - New Features

    - QPDF now supports reading and writing streams encoded with JPEG or RunLength encoding. Library API enhancements and command-line options have been added to control this behavior. See command-line options `--compress-streams` and `--decode-level` and methods `QPDFWriter::setCompressStreams` and `QPDFWriter::setDecodeLevel`.

    - QPDF is much better at recovering from broken files. In most cases, qpdf will skip invalid objects and will preserve broken stream data by not attempting to filter broken streams. QPDF is now able to recover or at least not crash on dozens of broken test files I have received over the past few years.

    - Page rotation is now supported and accessible from both the library and the command line.

    - `QPDFWriter` supports writing files in a way that preserves PCLm compliance in support of driverless printing. This is very specialized and is only useful to applications that already know how to create PCLm files.

  - Enhancements to the qpdf Command-line Tool. All new options listed here are documented in more detail in Running qpdf.

    - Command-line arguments can now be read from files or standard input using `@file` or `@-` syntax. Please see Basic Invocation.

    - `--rotate`: request page rotation

    - `--newline-before-endstream`: ensure that a newline appears before every `endstream` keyword in the file; used to prevent qpdf from breaking PDF/A compliance on already compliant files.

    - `--preserve-unreferenced`: preserve unreferenced objects in the input PDF

    - `--split-pages`: break output into chunks with fixed numbers of pages

    - `--verbose`: print the name of each output file that is created

    - `--compress-streams` and `--decode-level` replace `--stream-data` for improving granularity of controlling compression and decompression of stream data. The `--stream-data` option will remain available.

    - When running qpdf --check with other options, checks are always run first. This enables qpdf to perform its full recovery logic before outputting other information. This can be especially useful when manually recovering broken files, looking at qpdf’s regenerated cross reference table, or other similar operations.

    - Process --pages earlier so that other options like `--show-pages` or `--split-pages` can operate on the file after page splitting/merging has occurred.

  - API Changes. All new API calls are documented in their respective classes’ header files.

    - `QPDFObjectHandle::rotatePage`: apply rotation to a page object

    - `QPDFWriter::setNewlineBeforeEndstream`: force newline to appear before `endstream`

    - `QPDFWriter::setPreserveUnreferencedObjects`: preserve unreferenced objects that appear in the input PDF. The default behavior is to discard them.

    - New `Pipeline` types `Pl_RunLength` and `Pl_DCT` are available for developers who wish to produce or consume RunLength or DCT stream data directly. The `examples/pdf-create.cc` example illustrates their use.

    - `QPDFWriter::setCompressStreams` and `QPDFWriter::setDecodeLevel` methods control handling of different types of stream compression.

    - Add new C API functions `qpdf_set_compress_streams`, `qpdf_set_decode_level`, `qpdf_set_preserve_unreferenced_objects`, and `qpdf_set_newline_before_endstream` corresponding to the new `QPDFWriter` methods.

6.0.0: November 10, 2015

  - Implement `--deterministic-id` command-line option and `QPDFWriter::setDeterministicID` as well as C API function `qpdf_set_deterministic_ID` for generating a deterministic ID for non-encrypted files. When this option is selected, the ID of the file depends on the contents of the output file, and not on transient items such as the timestamp or output file name.

  - Make qpdf more tolerant of files whose xref table entries are not the correct length.

5.1.3: May 24, 2015

  - Bug fix: fix-qdf was not properly handling files that contained object streams with more than 255 objects in them.

  - Bug fix: qpdf was not properly initializing Microsoft’s secure crypto provider on fresh Windows installations that had not had any keys created yet.

  - Fix a few errors found by Gynvael Coldwind and Mateusz Jurczyk of the Google Security Team. Please see the ChangeLog for details.

  - Properly handle pages that have no contents at all. There were many cases in which qpdf handled this fine, but a few methods blindly obtained page contents with handling the possibility that there were no contents.

  - Make qpdf more robust for a few more kinds of problems that may occur in invalid PDF files.

5.1.2: June 7, 2014

  - Bug fix: linearizing files could create a corrupted output file under extremely unlikely file size circumstances. See ChangeLog for details. The odds of getting hit by this are very low, though one person did.

  - Bug fix: qpdf would fail to write files that had streams with decode parameters referencing other streams.

  - New example program: pdf-split-pages: efficiently split PDF files into individual pages. The example program does this more efficiently than using qpdf --pages to do it.

  - Packaging fix: Visual C++ binaries did not support Windows XP. This has been rectified by updating the compilers used to generate the release binaries.

5.1.1: January 14, 2014

  - Performance fix: copying foreign objects could be very slow with certain types of files. This was most likely to be visible during page splitting and was due to traversing the same objects multiple times in some cases.

5.1.0: December 17, 2013

  - Added runtime option (`QUtil::setRandomDataProvider`) to supply your own random data provider. You can use this if you want to avoid using the OS-provided secure random number generation facility or stdlib’s less secure version. See comments in include/qpdf/QUtil.hh for details.

  - Fixed image comparison tests to not create 12-bit-per-pixel images since some versions of tiffcmp have bugs in comparing them in some cases. This increases the disk space required by the image comparison tests, which are off by default anyway.

  - Introduce a number of small fixes for compilation on the latest clang in MacOS and the latest Visual C++ in Windows.

  - Be able to handle broken files that end the xref table header with a space instead of a newline.

5.0.1: October 18, 2013

  - Thanks to a detailed review by Florian Weimer and the Red Hat Product Security Team, this release includes a number of non-user-visible security hardening changes. Please see the ChangeLog file in the source distribution for the complete list.

  - When available, operating system-specific secure random number generation is used for generating initialization vectors and other random values used during encryption or file creation. For the Windows build, this results in an added dependency on Microsoft’s cryptography API. To disable the OS-specific cryptography and use the old version, pass the `--enable-insecure-random` option to ./configure.

  - The qpdf command-line tool now issues a warning when `-accessibility=n` is specified for newer encryption versions stating that the option is ignored. qpdf, per the spec, has always ignored this flag, but it previously did so silently. This warning is issued only by the command-line tool, not by the library. The library’s handling of this flag is unchanged.

5.0.0: July 10, 2013

  - Bug fix: previous versions of qpdf would lose objects with generation != 0 when generating object streams. Fixing this required changes to the public API.

  - Removed methods from public API that were only supposed to be called by QPDFWriter and couldn’t realistically be called anywhere else. See ChangeLog for details.

  - New `QPDFObjGen` class added to represent an object ID/generation pair. `QPDFObjectHandle::getObjGen()` is now preferred over `QPDFObjectHandle::getObjectID()` and `QPDFObjectHandle::getGeneration()` as it makes it less likely for people to accidentally write code that ignores the generation number. See `QPDF.hh` and `QPDFObjectHandle.hh` for additional notes.

  - Add `--show-npages` command-line option to the qpdf command to show the number of pages in a file.

  - Allow omission of the page range within `--pages` for the qpdf command. When omitted, the page range is implicitly taken to be all the pages in the file.

  - Various enhancements were made to support different types of broken files or broken readers. Details can be found in `ChangeLog`.

4.1.0: April 14, 2013

  - Note to people including qpdf in distributions: the `.la` files generated by libtool are now installed by qpdf’s make install target. Before, they were not installed. This means that if your distribution does not want to include `.la` files, you must remove them as part of your packaging process.

  - Major enhancement: API enhancements have been made to support parsing of content streams. This enhancement includes the following changes:

    - `QPDFObjectHandle::parseContentStream` method parses objects in a content stream and calls handlers in a callback class. The example `examples/pdf-parse-content.cc` illustrates how this may be used.

    - `QPDFObjectHandle` can now represent operators and inline images, object types that may only appear in content streams.

    - Method `QPDFObjectHandle::getTypeCode()` returns an enumerated type value representing the underlying object type. Method `QPDFObjectHandle::getTypeName()` returns a text string describing the name of the type of a `QPDFObjectHandle` object. These methods can be used for more efficient parsing and debugging/diagnostic messages.

  - qpdf --check now parses all pages’ content streams in addition to doing other checks. While there are still many types of errors that cannot be detected, syntactic errors in content streams will now be reported.

  - Minor compilation enhancements have been made to facilitate easier for support for a broader range of compilers and compiler versions.

    - Warning flags have been moved into a separate variable in `autoconf.mk`

    - The configure flag `--enable-werror` work for Microsoft compilers

    - All MSVC CRT security warnings have been resolved.

    - All C-style casts in C++ Code have been replaced by C++ casts, and many casts that had been included to suppress higher warning levels for some compilers have been removed, primarily for clarity. Places where integer type coercion occurs have been scrutinized. A new casting policy has been documented in the manual. This is of concern mainly to people porting qpdf to new platforms or compilers. It is not visible to programmers writing code that uses the library

    - Some internal limits have been removed in code that converts numbers to strings. This is largely invisible to users, but it does trigger a bug in some older versions of mingw-w64’s C++ library. See `README-windows.md` in the source distribution if you think this may affect you. The copy of the DLL distributed with qpdf’s binary distribution is not affected by this problem.

  - The RPM spec file previously included with qpdf has been removed. This is because virtually all Linux distributions include qpdf now that it is a dependency of CUPS filters.

  - A few bug fixes are included:

    - Overridden compressed objects are properly handled. Before, there were certain constructs that could cause qpdf to see old versions of some objects. The most usual manifestation of this was loss of filled in form values for certain files.

    - Installation no longer uses GNU/Linux-specific versions of some commands, so make install works on Solaris with native tools.

    - The 64-bit mingw Windows binary package no longer includes a 32-bit DLL.

4.0.1: January 17, 2013

  - Fix detection of binary attachments in test suite to avoid false test failures on some platforms.

  - Add clarifying comment in `QPDF.hh` to methods that return the user password explaining that it is no longer possible with newer encryption formats to recover the user password knowing the owner password. In earlier encryption formats, the user password was encrypted in the file using the owner password. In newer encryption formats, a separate encryption key is used on the file, and that key is independently encrypted using both the user password and the owner password.

4.0.0: December 31, 2012

  - Major enhancement: support has been added for newer encryption schemes supported by version X of Adobe Acrobat. This includes use of 127-character passwords, 256-bit encryption keys, and the encryption scheme specified in ISO 32000-2, the PDF 2.0 specification. This scheme can be chosen from the command line by specifying use of 256-bit keys. qpdf also supports the deprecated encryption method used by Acrobat IX. This encryption style has known security weaknesses and should not be used in practice. However, such files exist “in the wild,” so support for this scheme is still useful. New methods `QPDFWriter::setR6EncryptionParameters` (for the PDF 2.0 scheme) and `QPDFWriter::setR5EncryptionParameters` (for the deprecated scheme) have been added to enable these new encryption schemes. Corresponding functions have been added to the C API as well.

  - Full support for Adobe extension levels in PDF version information. Starting with PDF version 1.7, corresponding to ISO 32000, Adobe adds new functionality by increasing the extension level rather than increasing the version. This support includes addition of the `QPDF::getExtensionLevel` method for retrieving the document’s extension level, addition of versions of `QPDFWriter::setMinimumPDFVersion` and `QPDFWriter::forcePDFVersion` that accept an extension level, and extended syntax for specifying forced and minimum versions on the command line as described in `--force-version` and `--min-version`. Corresponding functions have been added to the C API as well.

  - Minor fixes to prevent qpdf from referencing objects in the file that are not referenced in the file’s overall structure. Most files don’t have any such objects, but some files have contain unreferenced objects with errors, so these fixes prevent qpdf from needlessly rejecting or complaining about such objects.

  - Add new generalized methods for reading and writing files from/to programmer-defined sources. The method `QPDF::processInputSource` allows the programmer to use any input source for the input file, and `QPDFWriter::setOutputPipeline` allows the programmer to write the output file through any pipeline. These methods would make it possible to perform any number of specialized operations, such as accessing external storage systems, creating bindings for qpdf in other programming languages that have their own I/O systems, etc.

  - Add new method `QPDF::getEncryptionKey` for retrieving the underlying encryption key used in the file.

  - This release includes a small handful of non-compatible API changes. While effort is made to avoid such changes, all the non-compatible API changes in this version were to parts of the API that would likely never be used outside the library itself. In all cases, the altered methods or structures were parts of the `QPDF` that were public to enable them to be called from either `QPDFWriter` or were part of validation code that was over-zealous in reporting problems in parts of the file that would not ordinarily be referenced. In no case did any of the removed methods do anything worse that falsely report error conditions in files that were broken in ways that didn’t matter. The following public parts of the `QPDF` class were changed in a non-compatible way:

    - Updated nested `QPDF::EncryptionData` class to add fields needed by the newer encryption formats, member variables changed to private so that future changes will not require breaking backward compatibility.

    - Added additional parameters to `compute_data_key`, which is used by `QPDFWriter` to compute the encryption key used to encrypt a specific object.

    - Removed the method `flattenScalarReferences`. This method was previously used prior to writing a new PDF file, but it has the undesired side effect of causing qpdf to read objects in the file that were not referenced. Some otherwise files have unreferenced objects with errors in them, so this could cause qpdf to reject files that would be accepted by virtually all other PDF readers. In fact, qpdf relied on only a very small part of what flattenScalarReferences did, so only this part has been preserved, and it is now done directly inside `QPDFWriter`.

    - Removed the method `decodeStreams`. This method was used by the `--check` option of the qpdf command-line tool to force all streams in the file to be decoded, but it also suffered from the problem of opening otherwise unreferenced streams and thus could report false positive. The `--check` option now causes qpdf to go through all the motions of writing a new file based on the original one, so it will always reference and check exactly those parts of a file that any ordinary viewer would check.

    - Removed the method `trimTrailerForWrite`. This method was used by `QPDFWriter` to modify the original QPDF object by removing fields from the trailer dictionary that wouldn’t apply to the newly written file. This functionality, though generally harmless, was a poor implementation and has been replaced by having QPDFWriter filter these out when copying the trailer rather than modifying the original QPDF object. (Note that qpdf never modifies the original file itself.)

  - Allow the PDF header to appear anywhere in the first 1024 bytes of the file. This is consistent with what other readers do.

  - Fix the pkg-config files to list zlib and pcre in `Requires.private` to better support static linking using pkg-config.

3.0.2: September 6, 2012

  - Bug fix: `QPDFWriter::setOutputMemory` did not work when not used with `QPDFWriter::setStaticID`, which made it pretty much useless. This has been fixed.

  - New API call `QPDFWriter::setExtraHeaderText` inserts additional text near the header of the PDF file. The intended use case is to insert comments that may be consumed by a downstream application, though other use cases may exist.

3.0.1: August 11, 2012

  - Version 3.0.0 included addition of files for pkg-config, but this was not mentioned in the release notes. The release notes for 3.0.0 were updated to mention this.

  - Bug fix: if an object stream ended with a scalar object not followed by space, qpdf would incorrectly report that it encountered a premature EOF. This bug has been in qpdf since version 2.0.

3.0.0: August 2, 2012

  - Acknowledgment: I would like to express gratitude for the contributions of Tobias Hoffmann toward the release of qpdf version 3.0. He is responsible for most of the implementation and design of the new API for manipulating pages, and contributed code and ideas for many of the improvements made in version 3.0. Without his work, this release would certainly not have happened as soon as it did, if at all.

  - Non-compatible API changes:

    - The method `QPDFObjectHandle::replaceStreamData` that uses a `StreamDataProvider` to provide the stream data no longer takes a `length` parameter. The parameter was removed since this provides the user an opportunity to simplify the calling code. This method was introduced in version 2.2. At the time, the `length` parameter was required in order to ensure that calls to the stream data provider returned the same length for a specific stream every time they were invoked. In particular, the linearization code depends on this. Instead, qpdf 3.0 and newer check for that constraint explicitly. The first time the stream data provider is called for a specific stream, the actual length is saved, and subsequent calls are required to return the same number of bytes. This means the calling code no longer has to compute the length in advance, which can be a significant simplification. If your code fails to compile because of the extra argument and you don’t want to make other changes to your code, just omit the argument.

    - Many methods take `long long` instead of other integer types. Most if not all existing code should compile fine with this change since such parameters had always previously been smaller types. This change was required to support files larger than two gigabytes in size.

  - Support has been added for large files. The test suite verifies support for files larger than 4 gigabytes, and manual testing has verified support for files larger than 10 gigabytes. Large file support is available for both 32-bit and 64-bit platforms as long as the compiler and underlying platforms support it.

  - Support for page selection (splitting and merging PDF files) has been added to the qpdf command-line tool. See Page Selection.

  - The `--copy-encryption` option have been added to the qpdf command-line tool for copying encryption parameters from another file.

  - New methods have been added to the `QPDF` object for adding and removing pages. See Adding and Removing Pages.

  - New methods have been added to the `QPDF` object for copying objects from other PDF files. See Copying Objects From Other PDF Files

  - A new method `QPDFObjectHandle::parse` has been added for constructing `QPDFObjectHandle` objects from a string description.

  - Methods have been added to `QPDFWriter` to allow writing to an already open stdio `FILE*` addition to writing to standard output or a named file. Methods have been added to `QPDF` to be able to process a file from an already open stdio `FILE*`. This makes it possible to read and write PDF from secure temporary files that have been unlinked prior to being fully read or written.

  - The `QPDF::emptyPDF` can be used to allow creation of PDF files from scratch. The example `examples/pdf-create.cc` illustrates how it can be used.

  - Several methods to take `PointerHolder<Buffer>` can now also accept `std::string` arguments.

  - Many new convenience methods have been added to the library, most in `QPDFObjectHandle`. See `ChangeLog` for a full list.

  - When building on a platform that supports ELF shared libraries (such as Linux), symbol versions are enabled by default. They can be disabled by passing `--disable-ld-version-script` to ./configure.

  - The file `libqpdf.pc` is now installed to support pkg-config.

  - Image comparison tests are off by default now since they are not needed to verify a correct build or port of qpdf. They are needed only when changing the actual PDF output generated by qpdf. You should enable them if you are making deep changes to qpdf itself. See `README.md` for details.

  - Large file tests are off by default but can be turned on with ./configure or by setting an environment variable before running the test suite. See `README.md` for details.

  - When qpdf’s test suite fails, failures are not printed to the terminal anymore by default. Instead, find them in `build/qtest.log`. For packagers who are building with an autobuilder, you can add the `--enable-show-failed-test-output` option to ./configure to restore the old behavior.

2.3.1: December 28, 2011

  - Fix thread-safety problem resulting from non-thread-safe use of the PCRE library.

  - Made a few minor documentation fixes.

  - Add workaround for a bug that appears in some versions of ghostscript to the test suite

  - Fix minor build issue for Visual C++ 2010.

2.3.0: August 11, 2011

  - Bug fix: when preserving existing encryption on encrypted files with cleartext metadata, older qpdf versions would generate password-protected files with no valid password. This operation now works. This bug only affected files created by copying existing encryption parameters; explicit encryption with specification of cleartext metadata worked before and continues to work.

  - Enhance `QPDFWriter` with a new constructor that allows you to delay the specification of the output file. When using this constructor, you may now call `QPDFWriter::setOutputFilename` to specify the output file, or you may use `QPDFWriter::setOutputMemory` to cause `QPDFWriter` to write the resulting PDF file to a memory buffer. You may then use `QPDFWriter::getBuffer` to retrieve the memory buffer.

  - Add new API call `QPDF::replaceObject` for replacing objects by object ID

  - Add new API call `QPDF::swapObjects` for swapping two objects by object ID

  - Add `QPDFObjectHandle::getDictAsMap` and `QPDFObjectHandle::getArrayAsVector` to allow retrieval of dictionary objects as maps and array objects as vectors.

  - Add functions `qpdf_get_info_key` and `qpdf_set_info_key` to the C API for manipulating string fields of the document’s `/Info` dictionary.

  - Add functions `qpdf_init_write_memory`, `qpdf_get_buffer_length`, and `qpdf_get_buffer` to the C API for writing PDF files to a memory buffer instead of a file.

2.2.4: June 25, 2011

  - Fix installation and compilation issues; no functionality changes.

2.2.3: April 30, 2011

  - Handle some damaged streams with incorrect characters following the stream keyword.

  - Improve handling of inline images when normalizing content streams.

  - Enhance error recovery to properly handle files that use object 0 as a regular object, which is specifically disallowed by the spec.

2.2.2: October 4, 2010

  - Add new function `qpdf_read_memory` to the C API to call `QPDF::processMemoryFile`. This was an omission in qpdf 2.2.1.

2.2.1: October 1, 2010

  - Add new method `QPDF::setOutputStreams` to replace `std::cout` and `std::cerr` with other streams for generation of diagnostic messages and error messages. This can be useful for GUIs or other applications that want to capture any output generated by the library to present to the user in some other way. Note that QPDF does not write to `std::cout` (or the specified output stream) except where explicitly mentioned in `QPDF.hh`, and that the only use of the error stream is for warnings. Note also that output of warnings is suppressed when `setSuppressWarnings(true)` is called.

  - Add new method `QPDF::processMemoryFile` for operating on PDF files that are loaded into memory rather than in a file on disk.

  - Give a warning but otherwise ignore empty PDF objects by treating them as null. Empty object are not permitted by the PDF specification but have been known to appear in some actual PDF files.

  - Handle inline image filter abbreviations when the appear as stream filter abbreviations. The PDF specification does not allow use of stream filter abbreviations in this way, but Adobe Reader and some other PDF readers accept them since they sometimes appear incorrectly in actual PDF files.

  - Implement miscellaneous enhancements to `PointerHolder` and `Buffer` to support other changes.

2.2.0: August 14, 2010

  - Add new methods to `QPDFObjectHandle` (`newStream` and `replaceStreamData` for creating new streams and replacing stream data. This makes it possible to perform a wide range of operations that were not previously possible.

  - Add new helper method in `QPDFObjectHandle` (`addPageContents`) for appending or prepending new content streams to a page. This method makes it possible to manipulate content streams without having to be concerned whether a page’s contents are a single stream or an array of streams.

  - Add new method in `QPDFObjectHandle`: `replaceOrRemoveKey`, which replaces a dictionary key with a given value unless the value is null, in which case it removes the key instead.

  - Add new method in `QPDFObjectHandle`: `getRawStreamData`, which returns the raw (unfiltered) stream data into a buffer. This complements the `getStreamData` method, which returns the filtered (uncompressed) stream data and can only be used when the stream’s data is filterable.

  - Provide two new examples: pdf-double-page-size and pdf-invert-images that illustrate the newly added interfaces.

  - Fix a memory leak that would cause loss of a few bytes for every object involved in a cycle of object references. Thanks to Jian Ma for calling my attention to the leak.

2.1.5: April 25, 2010

  - Remove restriction of file identifier strings to 16 bytes. This unnecessary restriction was preventing qpdf from being able to encrypt or decrypt files with identifier strings that were not exactly 16 bytes long. The specification imposes no such restriction.

2.1.4: April 18, 2010

  - Apply the same padding calculation fix from version 2.1.2 to the main cross reference stream as well.

  - Since qpdf --check only performs limited checks, clarify the output to make it clear that there still may be errors that qpdf can’t check. This should make it less surprising to people when another PDF reader is unable to read a file that qpdf thinks is okay.

2.1.3: March 27, 2010

  - Fix bug that could cause a failure when rewriting PDF files that contain object streams with unreferenced objects that in turn reference indirect scalars.

  - Don’t complain about (invalid) AES streams that aren’t a multiple of 16 bytes. Instead, pad them before decrypting.

2.1.2: January 24, 2010

  - Fix bug in padding around first half cross reference stream in linearized files. The bug could cause an assertion failure when linearizing certain unlucky files.

2.1.1: December 14, 2009

  - No changes in functionality; insert missing include in an internal library header file to support gcc 4.4, and update test suite to ignore broken Adobe Reader installations.

2.1: October 30, 2009

  - This is the first version of qpdf to include Windows support. On Windows, it is possible to build a DLL. Additionally, a partial C-language API has been introduced, which makes it possible to call qpdf functions from non-C++ environments. I am very grateful to Žarko Gajić (http://zarko-gajic.iz.hr/) for tirelessly testing numerous pre-release versions of this DLL and providing many excellent suggestions on improving the interface.

    For programming to the C interface, please see the header file `qpdf/qpdf-c.h` and the example `examples/pdf-linearize.c`.

  - Žarko Gajić has written a Delphi wrapper for qpdf, which can be downloaded from qpdf’s download side. Žarko’s Delphi wrapper is released with the same licensing terms as qpdf itself and comes with this disclaimer: “Delphi wrapper unit `qpdf.pas` created by Žarko Gajić (http://zarko-gajic.iz.hr/). Use at your own risk and for whatever purpose you want. No support is provided. Sample code is provided.”

  - Support has been added for AES encryption and crypt filters. Although qpdf does not presently support files that use PKI-based encryption, with the addition of AES and crypt filters, qpdf is now be able to open most encrypted files created with newer versions of Acrobat or other PDF creation software. Note that I have not been able to get very many files encrypted in this way, so it’s possible there could still be some cases that qpdf can’t handle. Please report them if you find them.

  - Many error messages have been improved to include more information in hopes of making qpdf a more useful tool for PDF experts to use in manually recovering damaged PDF files.

  - Attempt to avoid compressing metadata streams if possible. This is consistent with other PDF creation applications.

  - Provide new command-line options for AES encrypt, cleartext metadata, and setting the minimum and forced PDF versions of output files.

  - Add additional methods to the `QPDF` object for querying the document’s permissions. Although qpdf does not enforce these permissions, it does make them available so that applications that use qpdf can enforce permissions.

  - The `--check` option to qpdf has been extended to include some additional information.

  - Non-compatible API changes:

    - QPDF’s exception handling mechanism now uses `std::logic_error` for internal errors and `std::runtime_error` for runtime errors in favor of the now removed `QEXC` classes used in previous versions. The `QEXC` exception classes predated the addition of the `<stdexcept>` header file to the C++ standard library. Most of the exceptions thrown by the qpdf library itself are still of type `QPDFExc` which is now derived from `std::runtime_error`. Programs that catch an instance of `std::exception` and displayed it by calling the `what()` method will not need to be changed.

    - The `QPDFExc` class now internally represents various fields of the error condition and provides interfaces for querying them. Among the fields is a numeric error code that can help applications act differently on (a small number of) different error conditions. See `QPDFExc.hh` for details.

    - Warnings can be retrieved from qpdf as instances of `QPDFExc` instead of strings.

    - The nested `QPDF::EncryptionData` class’s constructor takes an additional argument. This class is primarily intended to be used by `QPDFWriter`. There’s not really anything useful an end-user application could do with it. It probably shouldn’t really be part of the public interface to begin with. Likewise, some of the methods for computing internal encryption dictionary parameters have changed to support `/R=4` encryption.

    - The method `QPDF::getUserPassword` has been removed since it didn’t do what people would think it did. There are now two new methods: `QPDF::getPaddedUserPassword` and `QPDF::getTrimmedUserPassword`. The first one does what the old `QPDF::getUserPassword` method used to do, which is to return the password with possible binary padding as specified by the PDF specification. The second one returns a human-readable password string.

    - The enumerated types that used to be nested in `QPDFWriter` have moved to top-level enumerated types and are now defined in the file `qpdf/Constants.h`. This enables them to be shared by both the C and C++ interfaces.

2.0.6: May 3, 2009

  - Do not attempt to uncompress streams that have decode parameters we don’t recognize. Earlier versions of qpdf would have rejected files with such streams.

2.0.5: March 10, 2009

  - Improve error handling in the LZW decoder, and fix a small error introduced in the previous version with regard to handling full tables. The LZW decoder has been more strongly verified in this release.

2.0.4: February 21, 2009

  - Include proper support for LZW streams encoded without the “early code change” flag. Special thanks to Atom Smasher who reported the problem and provided an input file compressed in this way, which I did not previously have.

  - Implement some improvements to file recovery logic.

2.0.3: February 15, 2009

  - Compile cleanly with gcc 4.4.

  - Handle strings encoded as UTF-16BE properly.

2.0.2: June 30, 2008

  - Update test suite to work properly with a non-bash `/bin/sh` and with Perl 5.10. No changes were made to the actual qpdf source code itself for this release.

2.0.1: May 6, 2008

  - No changes in functionality or interface. This release includes fixes to the source code so that qpdf compiles properly and passes its test suite on a broader range of platforms. See `ChangeLog` in the source distribution for details.

2.0: April 29, 2008

  - First public release.