README.md
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TABLE OF CONTENTS
- Welcome to Exiv2
- Building, Installing, Using and Uninstalling Exiv2
- Build, Install, Use and Uninstall Exiv2 on a UNIX-like system
- Build and Install Exiv2 with Visual Studio
- Build Options
- Dependencies
- Building and linking your code with Exiv2
- Consuming Exiv2 with CMake
- Using pkg-config to compile and link your code with Exiv2
- Localisation
- Building Exiv2 Documentation
- Building Exiv2 Packages
- Debugging Exiv2
- Building Exiv2 with Clang and other build chains
- Building Exiv2 with ccache
- License and Support
- Test Suit
- Platform Notes
# Welcome to Exiv2
Exiv2 is a C++ library and a command line utility to read,
write, delete and modify Exif, IPTC, XMP and ICC image metadata.
| Exiv2 Resource | Location |
|:------ |:---- |
| Releases and Documentation | [https://exiv2.org](https://exiv2.org) |
| Prereleases: | [https://pre-release.exiv2.org](https://pre-release.exiv2.org) |
| Project Resources | [https://github.com/Exiv2/exiv2](https://github.com/Exiv2/exiv2) |
| License (GPLv2) | [COPYING](COPYING) |
| CMake Downloads | [https://cmake.org/download/](https://cmake.org/download/) |
The file ReadMe.txt in a Build bundle describes how to install the library on the platform. ReadMe.txt also documents how to compile and link code on the platform.
[TOC](#TOC)
## 2 Building, Installing, Using and Uninstalling Exiv2
You need [CMake](https://cmake.org/download/) to configure the Exiv2 project and a C++11 compiler.
### 2.1 Build, Install, Use Exiv2 on a UNIX-like system
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This will install the library into the "standard locations". The library will be installed in `/usr/local/lib`, executables (including the exiv2 command-line program) in `/usr/local/bin/` and header files in `/usr/local/include/exiv2`
#### Using the exiv2 command-line program
To execute the exiv2 command line program, you should update your path to search /usr/local/bin/
?wzxhzdk:1?
You will also need to locate libexiv2 at run time:
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[TOC](#TOC)
### 2.2 Build and Install Exiv2 with Visual Studio
We recommend that you use conan to download the Exiv2 external dependencies on Windows (On Linux/OSX you can use or install system packages).
Apart from handling the dependencies, to configure and compile the project is pretty similar to the UNIX like systems.
See [README-CONAN](README-CONAN.md) for more information
[TOC](#TOC)
### 2.3 Build options
There are two groups of CMake options. There are many options defined by CMake. Here are some particularly useful options:
| Options | Purpose (_default_) |
|:------------- |:------------- |
| CMAKE\_INSTALL\_PREFIX
CMAKE\_BUILD\_TYPE
BUILD\_SHARED\_LIBS | Where to install on your computer _**(/usr/local)**_
Type of build _**(Release)**_ See: [Debugging Exiv2](#2-11)
Build exiv2lib as shared or static _**(On)**_ | Options defined by <exiv2>/CMakeLists.txt include: ?wzxhzdk:3? Options are defined on the CMake command line: ?wzxhzdk:4? [TOC](#TOC)
CMAKE\_BUILD\_TYPE
BUILD\_SHARED\_LIBS | Where to install on your computer _**(/usr/local)**_
Type of build _**(Release)**_ See: [Debugging Exiv2](#2-11)
Build exiv2lib as shared or static _**(On)**_ | Options defined by <exiv2>/CMakeLists.txt include: ?wzxhzdk:3? Options are defined on the CMake command line: ?wzxhzdk:4? [TOC](#TOC)
### 2.4 Dependencies
The following Exiv2 features require external libraries:
| Feature | Package | Default | To change default | Availability |
|:-------------------------- |:-------- |:--------:| :---------------------------- |:----------- |
| PNG image support | zlib | ON | -DEXIV2\_ENABLE\_PNG=Off | [http://zlib.net/](http://zlib.net/) |
| XMP support | expat | ON | -DEXIV2\_ENABLE\_XMP=Off | [http://expat.sourceforge.net](http://expat.sourceforge.net)/
Use _**Expat 2.2.6**_ and later | | Natural language system | gettext | OFF | -DEXIV2\_ENABLE\_NLS=On | [http://www.gnu.org/software/gettext/](http://www.gnu.org/software/gettext/) | On UNIX systems, you may install the dependencies using the distribution's package management system. Install the development package of a dependency to install the header files and libraries required to build Exiv2. In the file `ci/install_dependencies.sh` you can check to the list of packages we install on different Linux distributions. This file is used to setup some CI images in which we try out the Exiv2 compilation. Natural language system is discussed in more detail here: [Localisation](#2-8) Notes about different platforms are included here: [Platform Notes](#5) You may choose to install dependences with conan. This is supported on all platforms and is especially useful for users of Visual Studio. See [README-CONAN](README-CONAN.md) for more information. [TOC](#TOC)
Use _**Expat 2.2.6**_ and later | | Natural language system | gettext | OFF | -DEXIV2\_ENABLE\_NLS=On | [http://www.gnu.org/software/gettext/](http://www.gnu.org/software/gettext/) | On UNIX systems, you may install the dependencies using the distribution's package management system. Install the development package of a dependency to install the header files and libraries required to build Exiv2. In the file `ci/install_dependencies.sh` you can check to the list of packages we install on different Linux distributions. This file is used to setup some CI images in which we try out the Exiv2 compilation. Natural language system is discussed in more detail here: [Localisation](#2-8) Notes about different platforms are included here: [Platform Notes](#5) You may choose to install dependences with conan. This is supported on all platforms and is especially useful for users of Visual Studio. See [README-CONAN](README-CONAN.md) for more information. [TOC](#TOC)
### 2.5 Building and linking your code with Exiv2
There are detailed platform notes about compiling and linking in `releasenotes/{platform}/ReadMe.txt`
where `platform: { CYGWIN | Darwin | Linux | MinGW | msvc }`
In general you need to do the following:
1) Application code should be written in C++98 and include exiv2 headers:
?wzxhzdk:5?
2) Compile your C++ code with the directive: **`-I/usr/local/include`**
3) Link your code with libexiv2 using the linker options: **`-lexiv2`** and **`-L/usr/local/lib`**
The following is a typical command to build and link with libexiv2:
?wzxhzdk:6?
[TOC](#TOC)
### 2.6 Consuming Exiv2 with CMake
When exiv2 is installed, the files required to consume Exiv2 are installed in `${CMAKE_INSTALL_PREFIX}/lib/cmake/exiv2`
You can build samples/exifprint.cpp as follows:
?wzxhzdk:7?
This [repository](https://github.com/piponazo/exiv2Consumer) shows an example of how to consume Exiv2 with CMake.
[TOC](#TOC)
### 2.7 Using pkg-config to compile and link your code with Exiv2
When exiv2 is installed, the file exiv2.pc used by pkg-config is installed in `${CMAKE_INSTALL_PREFIX}/lib/pkgconfig` You will need to set the following in your environment:
?wzxhzdk:8?
To compile and link using exiv2.pc, you usually add the following to your Makefile.
?wzxhzdk:9?
If you are not using make, you can use pkg-config as follows:
?wzxhzdk:10?
[TOC](#TOC)
### 2.8 Localisation
Localisation is supported on a UNIX-like platform: Linux, MacOS-X, Cygwin and MinGW/msys2. Localisation is not supported for Visual Studio builds.
To build localisation support, use the CMake option `-DEXIV2_ENABLE_NLS=ON`. You must install the `gettext` package with your package manager or from source. The `gettext` package is available from [http://www.gnu.org/software/gettext/](http://www.gnu.org/software/gettext/) and includes the library `libintl` and utilities to build localisation files. If CMake produces error messages which mention libintl or gettext, you should verify that the package `gettext` has been correctly built and installed.
You must install the build to test localisation. This ensures that the localisation message files can be found at run-time. You cannot test localisation in the directory `build\bin`.
1) Running exiv2 in another language
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2) Adding additional languages to exiv2
To support a new language which we'll designate 'xy' for this discussion:
2.1) Generate a po file from the po template:
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2.2) Edit/Translate the strings in po/xy.po
I edited the following:
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to:
?wzxhzdk:14?
2.3) Generate the messages file:
?wzxhzdk:15?
2.4) Install and test your messages:
You have to install your messages to test them. It's not possible to test a messages file by executing build/bin/exiv2.
?wzxhzdk:16?
2.5) Submitting your new language file for inclusion in future versions of Exiv2:
You may submit a PR which contains po/xy.po AND a modification to po/CMakeLists.txt
Or, open a new issue on https://github.com/exiv2/exiv2 and attach the file xy.po.zip which can be created as follows:
?wzxhzdk:17?
[TOC](#TOC)
### 2.9 Building Exiv2 Documentation
Building documentation requires installing special tools. You will probably prefer to
read the documentation on-line from the project website: https://exiv2.org
To build documentation, use the CMake option **`-DEXIV2_BUILD_DOC=On`**.
Additionally, you will require an additional build step to actually build the documentation.
?wzxhzdk:18?
To build the documentation, you must install the following products:
| Product | Availability |
|:------------ |:------------ |
| doxygen
graphviz
python
xsltproc
md5sum | [http://www.doxygen.org/](http://www.doxygen.org/)
[http://www.graphviz.org/](http://www.graphviz.org/)
[http://www.python.org/](http://www.python.org/)
[http://xmlsoft.org/XSLT/](http://xmlsoft.org/XSLT/)
[http://www.microbrew.org/tools/md5sha1sum/](http://www.microbrew.org/tools/md5sha1sum/) | [TOC](#TOC)
graphviz
python
xsltproc
md5sum | [http://www.doxygen.org/](http://www.doxygen.org/)
[http://www.graphviz.org/](http://www.graphviz.org/)
[http://www.python.org/](http://www.python.org/)
[http://xmlsoft.org/XSLT/](http://xmlsoft.org/XSLT/)
[http://www.microbrew.org/tools/md5sha1sum/](http://www.microbrew.org/tools/md5sha1sum/) | [TOC](#TOC)
### 2.10 Building Exiv2 Packages
To enable the building of Exiv2 packages, use the CMake option `-DEXIV2_TEAM_PACKAGING=ON`.
You should not build Exiv2 Packages. This feature is intended for use by Team Exiv2 to create Platform and Source Packages on the buildserver.
There are two types of Exiv2 packages which are generated by cpack from the cmake command-line.
1) Platform Package (header files, binary library and samples. Some documentation and release notes)
Create and build exiv2 for your platform.
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2) Source Package
?wzxhzdk:20?
You may prefer to run `$ cmake --build . --config Release --target package_source`
[TOC](#TOC)
### 2.11 Debugging Exiv2
1) Generating and installing a debug library
In general to generate a debug library, you should use the option *cmake* option `-DCMAKE_RELEASE_TYPE=Debug` and build in the usual way.
?wzxhzdk:21?
You must install the library to ensure that your code is linked to the debug library.
You can check that you have generated a debug build with the command:
?wzxhzdk:22?
[TOC](#TOC)
2) About preprocessor symbols `NDEBUG` and `EXIV2_DEBUG_MESSAGES`
Exiv2 respects the symbol `NDEBUG` which is set only for Release builds. There are sequences of code which are defined within:
?wzxhzdk:23?
Those blocks of code are not compiled unless you define `EXIV2_DEBUG_MESSAGES` by yourself. They are provided for additional debugging information. For example, if you are interested in additional output from webpimage.cpp, you can update your build as follows:
?wzxhzdk:24?
If you are debugging library code, it is recommended that you use the exiv2 command-line as your test harness as Team Exiv2 is very familiar with this tool and able to give support.
[TOC](#TOC)
3) Starting the debugger
This is platform specific. On Linux:
?wzxhzdk:25?
[TOC](#TOC)
4) Using Debugger IDEs such as Xcode, CLion, Visual Studio, Eclipse or QtCreator
I have used all those IDEs to debug the Exiv2 library and applications. All of them work. You may find it takes initial effort, however I assure you that they all work well.
I personally use CLion which has excellent integration with CMake. It will automatically add **`-DCMAKE_BUILD_TYPE=Debug`** to the cmake command. It keeps build types in separate directories such as **`<exiv2dir>/cmake-build-debug`**.
[TOC](#TOC)
5) cmake --build . options **`--config Release|Debug`** and **`--target install`**
Visual Studio and Xcode can build debug or release builds without using the option **`-DCMAKE_BUILD_TYPE`** because the generated project files can build multiple types. The option **`--config Debug`** can be specified on the command-line to specify the build type. Alternatively, if you prefer to build in the IDE, the UI provides options to select the configuration and target.
With the Unix Makefile generator, the targets can be listed:
?wzxhzdk:26?
[TOC](#TOC)
### 2.12 Building Exiv2 with **clang** and other build chains
1) On Linux
?wzxhzdk:27?
**_OR_**
?wzxhzdk:28?
2) On MacOS-X
Apple provide clang with Xcode. GCC has not been supported by Apple since 2013. The _"normal unix build"_ uses Clang.
3) On Cygwin, MinGW/msys2, Windows (using clang-cl) and Visual Studio.
I have been unable to get clang to work on any of those platforms.
4) Cross Compiling
I've never succeeded in getting this to work. I use different VMs for Linux 32 and 64 bit. I've documented how to set up Cygwin and MinGW/msys2 for 64 and 32 bit builds in [README-CONAN](README-CONAN.md)
[TOC](#TOC)
### 2.13 Building Exiv2 with ccache
To speed up compilation, the utility ccache can be installed to cache the output of the compiler. This greatly speeds up the build when you frequently built code that has not been modified.
Installing and using ccache (and other similar utilities), is platform dependent. On Ubuntu:
?wzxhzdk:29?
To build with ccache, use the cmake option **-DBUILD\_WITH\_CCACHE=On**
?wzxhzdk:30?
Due to the way in which ccache is installed in Fedora (and other Linux distros), ccache effectively replaces the compiler. A default build or **-DBUILD\_WITH\_CCACHE=Off** is not effective and the environment variable CCACHE_DISABLE is required to disable ccache. [https://github.com/Exiv2/exiv2/issues/361](https://github.com/Exiv2/exiv2/issues/361)
[TOC](#TOC)
## 3 License and Support
All project resources are accessible from the project website.
https://github.com/Exiv2/exiv2
### 3.1 License
Copyright (C) 2004-2019 Exiv2 authors.
You should have received a copy of the file [COPYING](COPYING) which details the GPLv2 license.
Exiv2 is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
Exiv2 program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
[TOC](#TOC)
### 3.2 Support
For new bug reports and feature requests, please open an issue in Github.
[TOC](#TOC)
## 4 Running the test suite
The test suite is a mix of bash and python scripts. The python scripts are new to v0.27 and the bash scripts are being replaced as time permits.
### 4.1 Running tests on a UNIX-like system
You can run the suite directly from the build:
?wzxhzdk:31?
You can run individual tests in the test directory using the environment variable EXIV2\_BINDIR to specify the location of the build artifacts. For Cygwin and MinGW/msys builds, also set EXIV2_EXT=.exe
?wzxhzdk:32?
[TOC](#TOC)
### 4.2 Running tests on Visual Studio builds
Use the bash interpreter for MinGW/msys2 to run the test suite. It's essential to have a DOS Python3 interpreter on your path called `python3.exe` The variables EXIV2\_BINDIR and EXIV2\_EXT enable the test suite to locate the MSVC build artifacts.
?wzxhzdk:33?
**Caution: ** The python3 interpreter must be for DOS and called python3.exe. I copied `c:\Python37\python.exe c:\Python37\python3.exe`
Once you have modified the PATH and and exported EXIV2\_BINDIR and EXIV2\_EXT, you can execute the test suite as described for UNIX-like systems:
?wzxhzdk:34?
[TOC](#TOC)
### 4.3 Unit tests
The code for the unit tests is in `<exiv2dir>/unitTests`
To build the unit tests, use the *cmake* option `-DEXIV2_BUILD_UNIT_TESTS=ON`.
To execute the unit tests:
?wzxhzdk:35?
There is a discussion on the web about installing GTest: [https://github.com/Exiv2/exiv2/issues/575](https://github.com/Exiv2/exiv2/issues/575)
[TOC](#TOC)
## 5 Platform Notes
There are many ways to set up and configure your platform. The following notes are provided as a guide.
### 5.1 Linux
Update your system and install the build tools and dependencies (zlib, expat, gtest and others)
?wzxhzdk:36?
Get the code from GitHub and build
?wzxhzdk:37?
[TOC](#TOC)
### 5.2 MacOS-X
You will need to install Xcode and the Xcode command-line tools to build on the Mac.
You should build and install libexpat and zlib. You may use brew, macports, build from source, or use conan.
I recommend that you build and install CMake from source.
[TOC](#TOC)
### 5.3 MinGW
We provide support for both 64bit and 32bit builds using MinGW/msys2. [https://www.msys2.org](https://www.msys2.org)
Support for MinGW/msys1.0 32 bit build was provided for Exiv2 v0.26. MinGW/msys1.0 is not supported by Team Exiv2 for Exiv2 v0.27 and later.
There is a discussion on the web about installing GTest: [https://github.com/Exiv2/exiv2/issues/575](https://github.com/Exiv2/exiv2/issues/575)
#### MinGW/msys2 64 bit
Install: [http://repo.msys2.org/distrib/x86\_64/msys2-x86\_64-20180531.exe](http://repo.msys2.org/distrib/x86_64/msys2-x86_64-20180531.exe)
I use the following batch file to start the MinGW/msys2 64 bit bash shell from the Dos Command Prompt (cmd.exe)
?wzxhzdk:38?
#### MinGW/msys2 32 bit
Install: [http://repo.msys2.org/distrib/i686/msys2-i686-20180531.exe](http://repo.msys2.org/distrib/i686/msys2-i686-20180531.exe)
I use the following batch file to start the MinGW/msys2 32 bit bash shell from the Dos Command Prompt (cmd.exe)
?wzxhzdk:39?
#### Install MinGW Dependencies
Install tools and dependencies:
?wzxhzdk:40?
You can upgrade all installed packages on your system with the following command. For me, this broke msys32 and I had to reinstall msys32 and all the dependencies. Your experience may be different.
?wzxhzdk:41?
#### Download exiv2 from github and build
?wzxhzdk:42?
#### MinGW and Regex
The exiv2 command line program provides an option **`--grep`** to filter output. The implementation requires the header file **`<regex.h>`** and supporting library to be available during the build. When not available, the option **`--grep`** degrades to a substring match. Because there are several versions of **`<regex.h>`** available on the MinGW platform, detection of regex is always disabled on this platform and uses substring match. The following command reveals if regex is included in your build:
?wzxhzdk:43?
[TOC](#TOC)
### 5.4 Cygwin
Download: [https://cygwin.com/install.html](https://cygwin.com/install.html) and run setup-x86_64.exe for 64 Bit Cygwin, or setup-x86.exe for 32 bit Cygwin. I install into c:\\cygwin64 and c:\\cygwin32
You need:
make, cmake, gcc, gettext-devel pkg-config, dos2unix, zlib-devel, libexpat1-devel, git, python3-interpreter, libiconv, libxml2-utils, libncurses.
Download and build libiconv-1.15: [https://ftp.gnu.org/pub/gnu/libiconv/libiconv-1.15.tar.gz](https://ftp.gnu.org/pub/gnu/libiconv/libiconv-1.15.tar.gz)
There is a discussion on the web about installing GTest: [https://github.com/Exiv2/exiv2/issues/575](https://github.com/Exiv2/exiv2/issues/575)
Download and build cmake from source because I can't get the cygwin installed cmake 3.6.2 to work.
To build cmake from source, you need libncurses. [https://cmake.org/download/](https://cmake.org/download/)
I use the following batch file "cygwin64.bat" to start the Cygwin/64 bit bash shell from the Dos Command Prompt (cmd.exe).
?wzxhzdk:44?
[TOC](#TOC)
### 5.5 Microsoft Visual C++
We recommend that you use Conan to build Exiv2 using Microsoft Visual C++. Exiv2 v0.27 can be built with Visual Studio versions 2008 and later. We actively support and build with Visual Studio 2015, 2017 and 2019.
As well as Microsoft Visual Studio, you will need to install CMake, Python3, and Conan.
1) Binary installers for CMake on Windows are availably from [https://cmake.org/download/](https://cmake.org/download/).
2) Binary installers for Python3 are available from [python.org](https://python.org)
3) Conan can be installed using python/pip. Details in [README-CONAN.md](README-CONAN.md) I use the following batch file to start cmd.exe. I do this to reduce the complexity of the path which grows as various tools are installed on Windows. The purpose of this script is to ensure a "stripped down path". ?wzxhzdk:45? [TOC](#TOC)
2) Binary installers for Python3 are available from [python.org](https://python.org)
3) Conan can be installed using python/pip. Details in [README-CONAN.md](README-CONAN.md) I use the following batch file to start cmd.exe. I do this to reduce the complexity of the path which grows as various tools are installed on Windows. The purpose of this script is to ensure a "stripped down path". ?wzxhzdk:45? [TOC](#TOC)
### 5.6 Unix
Exiv2 can be built on many Unix and Linux distros. With v0.27.2, we are starting to actively support the Unix Distributions NetBSD and FreeBSD. We hope to add CI support for these platforms in v0.27.3.
I have provided notes here based on my experience with these platforms. Feedback is welcome.
I am willing to support Exiv2 on other commercial Unix distributions such as AIX, HP-UX and OSF/1 provided you provide with an ssh account for your platform. I will require super-user privileges to install software.
#### NetBSD
You can build exiv2 from source using the methods described for linux. I built and installed exiv2 using "Pure CMake" and didn't require conan.
You will want to use the package manager `pkgsrc` to build/install:
1. gcc (currently GCC 5.5.0)
2. python3
3. cmake
4. bash
5. sudo
6. chksum
7. gettext
I entered links into the file system `# ln -s /usr/pkg/bin/python37 /usr/local/bin/python3` and `# ln -s /usr/pkg/bin/bash /bin/bash`
It's important to ensure that `LD_LIBRARY_PATH` includes `/usr/local/lib` and `/usr/pkg/lib`. It's important to ensure that PATH includes `/usr/local/bin`, `/usr/pkg/bin` and `/usr/pkg/sbin`.
#### FreeBSD
Clang is pre-installed as ``/usr/bin/{cc|c++}` as well has libz and expat. FreeBSD uses pkg as the package manager which I used to install cmake and git.
?wzxhzdk:46?
To run the Exiv2 test suite, I installed bash and python. The test suite requires additional work as the platform `diff` command does not understand the option `--binary` and returns an error. In consequence, the test harness returns lots of errors. I hope to address this in v0.27.3.
?wzxhzdk:47?
#### Solaris
Work in progress: [https://github.com/Exiv2/exiv2/issues/902](https://github.com/Exiv2/exiv2/issues/902)
[TOC](#TOC)
Robin Mills
Revised: 2019-07-29