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Fixes to ChangeLog and manual for 10.0.0 changes

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Jay Berkenbilt 2020-04-05 21:46:21 -04:00
parent 98174373b9
commit 3d0de5b924
3 changed files with 293 additions and 18 deletions
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16
ChangeLog
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@ -8,6 +8,12 @@
recovery when objects are copied from other files and when
"immediate copy from" is enabled.
* When copying foreign streams with immediateCopyFrom set, the
same type of recovery from streams with filtering errors is
performed as when dealing with streams in the original input. This
could happen, for example, if you are using the --pages option to
take pages from another file and that file has errors in it.
* Add a new version of QPDFObjectHandle::pipeStreamData whose
return value indicates overall success or failure rather than
whether nor not filtering was attempted. It should have always
@ -36,6 +42,12 @@
--preserve-unreferenced-resources is now a synonym for
--remove-unreferenced-resources=no.
* Use std::atomic for unique ID generation internally within the
library. This eliminates the already extremely low chance of a
collision, improves thread safety, and removes a dependency on a
random number generator. Thanks to Dean Scarff for the
contribution.
2020-04-03 Jay Berkenbilt <ejb@ql.org>
* Allow qpdf to be built on systems without wchar_t. All "normal"
@ -50,6 +62,10 @@
maximally fill the destination rectangle. Prior to this change,
placeFormXObject might shrink it but would never expand it.
* When calling the C API, accept any non-zero value as TRUE rather
than just 1. This appears to resolve issues on Windows when
calling some versions of the DLL directly from other languages.
2020-04-02 Jay Berkenbilt <ejb@ql.org>
* Add method QPDFObjectHandle::unsafeShallowCopy for copying only

291
manual/qpdf-manual.xml
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@ -1944,21 +1944,51 @@ outfile.pdf</option>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--remove-unreferenced-resources=<replaceable>option</replaceable></option></term>
<listitem>
<para>
The <replaceable>option</replaceable> may be
<literal>auto</literal>, <literal>yes</literal>, or
<literal>no</literal>. The default is <literal>auto</literal>.
</para>
<para>
Starting with qpdf 8.1, when splitting pages, qpdf is able to
attempt to remove images and fonts that are not used by a page
even if they are referenced in the page's resources
dictionary. When shared resources are in use, this behavior
can greatly reduce the file sizes of split pages, but the
analysis is very slow. In versions from 8.1 through 9.1.1,
qpdf did this analysis by default. Starting in qpdf 10.0.0, if
<literal>auto</literal> is used, qpdf does a quick analysis of
the file to determine whether the file is likely to have
unreferenced objects on pages, a pattern that frequently
occurs when resource dictionaries are shared across multiple
pages and rarely occurs otherwise. If it discovers this
pattern, then it will attempt to remove unreferenced
resources. Usually this means you get the slower splitting
speed only when it's actually going to create smaller files.
You can suppress removal of unreferenced resources altogether
by specifying <literal>no</literal> or force it to do the full
algorithm by specifying <literal>yes</literal>.
</para>
<para>
Other than cases in which you don't care about file size and
care a lot about runtime, there are few reasons to use this
option, especially now that <literal>auto</literal> mode is
supported. One reason to use this is if you suspect that qpdf
is removing resources it shouldn't be removing. If you
encounter that case, please report it as bug at <ulink
url="https://github.com/qpdf/qpdf/issues/">https://github.com/qpdf/qpdf/issues/</ulink>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--preserve-unreferenced-resources</option></term>
<listitem>
<para>
Starting with qpdf 8.1, when splitting pages, qpdf ordinarily
attempts to remove images and fonts that are not used by a
page even if they are referenced in the page's resources
dictionary. This option suppresses that behavior. There are
few reasons to use this option. One reason to use this is if
you suspect that qpdf is removing resources it shouldn't be
removing. If you encounter that case, please report it as a
bug. Another reason is that the new behavior can be much
slower for files that include a very large number of images or
other XObjects on a page. In that case, using this option will
return qpdf to the old behavior and speed.
This is a synonym for
<option>--remove-unreferenced-resources=no</option>.
</para>
<para>
See also <option>--preserve-unreferenced</option>, which does
@ -4700,6 +4730,239 @@ print "\n";
<filename>ChangeLog</filename> in the source distribution.
</para>
<variablelist>
<!--
<varlistentry>
<term>x.y.z: Month dd, YYYY</term>
<listitem>
<itemizedlist>
<listitem>
<para>
Category
</para>
<itemizedlist>
<listitem>
<para>
Item
</para>
</listitem>
<listitem>
<para>
Item
</para>
</listitem>
</itemizedlist>
</listitem>
<listitem>
<para>
Category
</para>
<itemizedlist>
<listitem>
<para>
Item
</para>
</listitem>
<listitem>
<para>
Item
</para>
</listitem>
</itemizedlist>
</listitem>
</itemizedlist>
</listitem>
</varlistentry>
-->
<varlistentry>
<term>10.0.0: April 6, 2020</term>
<listitem>
<itemizedlist>
<listitem>
<para>
Performance Enhancements
</para>
<itemizedlist>
<listitem>
<para>
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.
</para>
</listitem>
</itemizedlist>
</listitem>
<listitem>
<para>
CLI Enhancements
</para>
<itemizedlist>
<listitem>
<para>
Add <literal>objectinfo</literal> 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 <command>qpdf
--json-help</command> for details.
</para>
</listitem>
<listitem>
<para>
Add new option
<option>--remove-unreferenced-resources</option> which takes
<literal>auto</literal>, <literal>yes</literal>, or
<literal>no</literal> as arguments. The new
<literal>auto</literal> 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. See
<xref linkend="ref.advanced-transformation"/> for a more
detailed discussion.
</para>
</listitem>
<listitem>
<para>
The <option>--preserve-unreferenced-resources</option> is
now just a synonym for
<option>--remove-unreferenced-resources=no</option>.
</para>
</listitem>
<listitem>
<para>
If the <literal>QPDF_EXECUTABLE</literal> environment
variable is set when invoking <command>qpdf
--bash-completion</command> or <command>qpdf
--zsh-completion</command>, the completion command that it
outputs will refer to qpdf using the value of that variable
rather than what <command>qpdf</command> determines its
executable path to be. This can be useful when wrapping
<command>qpdf</command> with a script, working with a
version in the source tree, using an AppImage, or other
situations where there is some indirection.
</para>
</listitem>
</itemizedlist>
</listitem>
<listitem>
<para>
Library Enhancements
</para>
<itemizedlist>
<listitem>
<para>
Add a new version of
<function>QPDFObjectHandle::StreamDataProvider::provideStreamData</function>
that accepts the <function>suppress_warnings</function> and
<function>will_retry</function> options and allows a success
code to be returned. This makes it possible to implement a
<classname>StreamDataProvider</classname> that calls
<function>pipeStreamData</function> on another stream and to
pass the response back to the caller, which enables better
error handling on those proxied streams.
</para>
</listitem>
<listitem>
<para>
Update <function>QPDFObjectHandle::pipeStreamData</function>
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.
</para>
</listitem>
<listitem>
<para>
The
<function>QPDFPageObjectHelper::placeFormXObject</function>
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.
</para>
</listitem>
<listitem>
<para>
When calling the C API, any non-zero value passed to a
boolean parameter is treated as <literal>TRUE</literal>.
Previously only the value <literal>1</literal> 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.
</para>
</listitem>
<listitem>
<para>
Add <function>QPDFObjectHandle::unsafeShallowCopy</function>
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
<emphasis>know</emphasis> you are only inserting or
replacing top-level items, it is much faster than
<function>QPDFObjectHandle::shallowCopy</function>.
</para>
</listitem>
<listitem>
<para>
Add <function>QPDFObjectHandle::filterAsContents</function>,
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.
</para>
</listitem>
</itemizedlist>
</listitem>
<listitem>
<para>
Bug Fixes
</para>
<itemizedlist>
<listitem>
<para>
When detecting and removing unreferenced resources during
page splitting, traverse into form XObjects and handle their
resources dictionaries as well.
</para>
</listitem>
<listitem>
<para>
The same error recovery is applied to streams in other than
the primary input file when merging or splitting pages.
</para>
</listitem>
</itemizedlist>
</listitem>
<listitem>
<para>
Build Changes
</para>
<itemizedlist>
<listitem>
<para>
Allow qpdf to built on stripped down systems whose C/C++
libraries lack the <classname>wchar_t</classname> type.
Search for <classname>wchar_t</classname> in qpdf's
README.md for details. This should be very rare, but it is
known to be helpful in some embedded environments.
</para>
</listitem>
</itemizedlist>
</listitem>
</itemizedlist>
</listitem>
</varlistentry>
<varlistentry>
<term>9.1.1: January 26, 2020</term>
<listitem>
@ -4804,8 +5067,6 @@ print "\n";
</itemizedlist>
</listitem>
</varlistentry>
</variablelist>
<variablelist>
<varlistentry>
<term>9.1.0: November 17, 2019</term>
<listitem>
@ -4905,8 +5166,6 @@ print "\n";
</itemizedlist>
</listitem>
</varlistentry>
</variablelist>
<variablelist>
<varlistentry>
<term>9.0.2: October 12, 2019</term>
<listitem>
@ -5272,7 +5531,7 @@ print "\n";
in dynamically linked code catching exceptions or
subclassing, this could be the reason. If you see this,
please report a bug at <ulink
url="https://github.com/qpdf/qpdf/issues/">pikepdf</ulink>.
url="https://github.com/qpdf/qpdf/issues/">https://github.com/qpdf/qpdf/issues/</ulink>.
</para>
</listitem>
<listitem>

4
qpdf/qpdf.cc
View File

@ -1483,10 +1483,10 @@ ArgParser::argHelp()
<< "--normalize-content=[yn] enables or disables normalization of content streams\n"
<< "--object-streams=mode controls handing of object streams\n"
<< "--preserve-unreferenced preserve unreferenced objects\n"
<< "--preserve-unreferenced-resources\n"
<< " synonym for --remove-unreferenced-resources=no\n"
<< "--remove-unreferenced-resources={auto,yes,no}\n"
<< " whether to remove unreferenced page resources\n"
<< "--preserve-unreferenced-resources\n"
<< " synonym for --remove-unreferenced-resources=no\n"
<< "--newline-before-endstream always put a newline before endstream\n"
<< "--coalesce-contents force all pages' content to be a single stream\n"
<< "--flatten-annotations=option\n"