Qpdf For Windows

[Dion Worles]

Whenrunning the checks for my R-package (via devtools::check()) I face the warning ''qpdf' is needed for checks on size reduction of PDFs. I found this question were it was suggested (if I understood the answer correctly) to run Sys.which(Sys.getenv("R_QPDF", "qpdf")) and see whether qpdf is found or not. In my case this just returns

so, I think I didn't install qpdf correctly. Unfortunately it seems to be quite complicated to install qpdf on Windows. My first side question is: does it really is so painful and complicated to install qpdf for Windows or is there an easy solution?

I've followed the instructions until it is said to add C:\MinGW-w64\bin and C:\MinGW-w64\lib\mingw to the PATH variable. But then I don't find further specific instructions to install qpdf, only about how to build qpdf with different other programs. The second side question is: is my assumption correct that after I've build qpdf it is installed? But the real question is: What is the best way to build qpdf? I tried the ./config-mingw32 and ./config-mingw64 commands from the section "Building with MinGW" in my C:\MinGW\msys\1.0\bin\bash.exe but got the error messages ./config-mingw32: No such file or directory and have no idea how to fix this issue.

If you are running the 32-bit version of R, it is important that you download the 32-bit version of qpdf, which is the version linked from the SourceForge homepage. If you are running a 64-bit installation of R, you will need to do a bit of digging to locate the 64-bit version of qpdf, which is buried a little more deeply (version 10.0.1 is listed here).

Rather than copying files to C:/Windows/System32, a potentially safer option is to extracted the zipped qpdf directory to C:\Program Files. If you do this, you'll need to add C:\Program Files\qpdf-version_number\bin to your system PATH under the environment variables.

One further step may be required to convince Windows that pqdf is safe to run.Navigate to C:\Program Files\qpdf-version_numer\bin and execute qpdf.exe (by double-clicking). Windows 10 throws up a security warning, as it's an unrecognized executable file. You'll need to use the more options link to find the button to run the program. This done, Windows will recognize the file as safe to run and allow other software, including R, to use it.

I spent hours trying to install QPDF on my computer (Windows 10) just to see this. Is QPDF bad for windows or is this some technical error? How can I fix this? Because I badly need to edit some pdf files.

As long as you trust the program, cou can click on More Info and let Windows run the application. If you are not 100% sure, you can always scan the whole program folder with any anti virus software, but keep in mind that not every virus can be 100% detected.

Content-preserving transformations transformations of PDF files such as split, combine, and compress. This package interfaces directly to the 'qpdf' C++ API and does not require any command line utilities. Note that 'qpdf' does not read actual content from PDF files: to extract text and data you need the 'pdftools' package.

Note: prior to qpdf 11, image comparison tests were enabled withinqpdf.test, and you had to disable them by settingQPDF_SKIP_TEST_COMPARE_IMAGES to 1. This was doneautomatically by ./configure. Now you have to enable imagecomparison tests by setting an environment variable. This change wasmade because developers have to set the environment variablethemselves now rather than setting it through the build. Either way,they are off by default.

If you are using a multi-configuration generator such as MSVC, youshould pass --config (where is Release,Debug, RelWithDebInfo, or MinSizeRel as discussed in theCMake documentation) to the build command. If you are running asingle configuration generator such as the default Makefile generatorsin Linux or MSYS, you may want to pass -DCMAKE_BUILD_TYPE=to the original cmake command.

Run ctest to run the test suite. Since the real tests areimplemented with qtest, you willwant to pass --verbose to cmake so you can see the individualtest outputs. Otherwise, you will see a small number of ctestcommands that take a very long to run. If you want to run only aspecific test file in a specific test suite, you can set the TESTSenvironment variable (used by qtest-driver) and pass the -Rparameter to ctest. For example:

Installation can be performed using cmake --install or cpack.For most normal use cases, cmake --install or cpack can be runin the normal way as described in CMake documentation. qpdf followsall normal installation conventions and uses CMake-defined variablesfor standard behavior.

Note that the lib component installs only runtime libraries, notheader files or other files/links needed to build against qpdf. Forthat, you need dev. If you are using shared libraries, the devwill install files or create symbolic links that depend on filesinstalled by lib, so you will need to install both. If you wantedto build software against the qpdf library and only wanted to installthe files you needed for that purpose, here are some examples:

All available build options are defined in the the top-levelCMakeLists.txt file and have help text. You can see them usingany standard cmake front-end (like cmake-gui or ccmake). Thissection describes options that apply to most users. If you are tryingto map autoconf options (from prior to qpdf 11) to cmake options,please see Converting From autoconf to cmake.

On Windows, if you build with shared libraries, you must have theoutput directory for libqpdf (e.g. libqpdf/Release orlibqpdf within the build directory) in your path so that thecompiled executables can find the DLL. Updating your path is notnecessary if you build with static libraries only.

This option enables changes planned for the next major release to beincluded. They are NOT part of the stable API. These changes are ABIbreaking and are subject to change, which means code linked againsta qpdf built with this option may not be binary compatible withinstalled qpdf libraries. Set this if you want to test your codewith proposed QPDF API changes and provide feedback prior to theinclusion of those changes in a release. Packagers should neverdistribute packages built with this option.

Some qpdf source files are automatically generated fromjob.yml and the CLI documentation. If you are adding newcommand-line arguments to the qpdf CLI or updatingmanual/cli.rst in the qpdf sources, you should turn this on.This option requires Python 3.

Since version 9.1.0, qpdf can use external crypto providers inaddition to its native provider. For a general discussion, seeCrypto Providers. This section discusses how to configure which cryptoproviders are compiled into qpdf.

In nearly all cases, external crypto providers should be preferredover the native one. However, if you are not concerned about workingwith encrypted files and want to reduce the number of dependencies,the native crypto provider is fully supported.

This option is only available when USE_IMPLICIT_CRYPTO is selected,in which case it is on by default. Turning it off prevents qpdf fromfalling back to the native crypto provider when no external provideris available.

Explicitly select which crypto provider is used by default. SeeRuntime Crypto Provider Selection for information about run-time selection ofthe crypto provider. If not specified, qpdf will pick gnutls ifavailable, otherwise openssl if available, and finally native as alast priority.

By default, installing qpdf does not include a pre-built copy of themanual. Instead, it installs a README file that tells people whereto find the manual online. If you want to install the manual, youmust enable the INSTALL_MANUAL option, and you must have adoc-dist directory in the manual directory of the build. Thedoc-dist directory is created if BUILD_DOC_DIST is selectedand BUILD_DOC_PDF and BUILD_DOC_HTML are both on.

If you are building in an environment that does not supportwchar_t, you can define the preprocessor symbolQPDF_NO_WCHAR_T in your build. This will work whether you arebuilding qpdf and need to avoid compiling the code that uses wchar_tor whether you are building client code that uses qpdf.

Note that, when you build code with libqpdf, it is not necessary tohave the definition of QPDF_NO_WCHAR_T in your build match whatwas defined when the library was built as long as you are not callingany of the methods that use wchar_t.

The available crypto provider implementations are gnutls,openssl, and native. OpenSSL support was added in qpdf 10.0.0with support for OpenSSL added in 10.4.0. GnuTLS support wasintroduced in qpdf 9.1.0. Additional implementations can be added asneeded. It is also possible for a developer to provide their ownimplementation without modifying the qpdf library.

You can use the --show-crypto option to qpdf toget a list of available crypto providers. The default provider isalways listed first, and the rest are listed in lexical order. Eachcrypto provider is listed on a line by itself with no other text,enabling the output of this command to be used easily in scripts.

You can override which crypto provider is used by setting theQPDF_CRYPTO_PROVIDER environment variable. There are few reasonsto ever do this, but you might want to do it if you were explicitlytrying to compare behavior of two different crypto providers whiletesting performance or reproducing a bug. It could also be useful forpeople who are implementing their own crypto providers.

If you are writing code that uses libqpdf and you want to force acertain crypto provider to be used, you can call the methodQPDFCryptoProvider::setDefaultProvider. The argument is the nameof a built-in or developer-supplied provider. To add your own cryptoprovider, you have to create a class derived from QPDFCryptoImpland register it with QPDFCryptoProvider. For additionalinformation, see comments in include/qpdf/QPDFCryptoImpl.hh.

Versions of qpdf before qpdf 11 were built with autoconf and ahome-grown GNU Make-based build system. If you built qpdf with special./configure options, this section can help you switch them over tocmake.

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