Development/Tutorials/CMake/KDE4: Difference between revisions

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    {{Template:I18n/Language Navigation Bar|Development/Tutorials/CMake}}


    == Introduction ==
    == Introduction ==
    Line 21: Line 20:


    Once downloaded, unpack and compile it:
    Once downloaded, unpack and compile it:
    <code>
    <syntaxhighlight lang="bash">
    $ mkdir cmake-build
    $ mkdir cmake-build
    $ cd cmake-build
    $ cd cmake-build
    Line 27: Line 26:
    $ make
    $ make
    $ make install
    $ make install
    </code>
    </syntaxhighlight>


    By default, this will install CMake in /usr/local, so make sure to have /usr/local/bin in your execute path.  To change the installation prefix (e.g. to /usr in debian), add the '--prefix=PATH' option to the bootstrap command.
    By default, this will install CMake in /usr/local, so make sure to have /usr/local/bin in your execute path.  To change the installation prefix (e.g. to /usr in debian), add the '--prefix=PATH' option to the bootstrap command.
    Line 48: Line 47:


    So, let's say you have kdelibs/ in ~/src/kdelibs/, then do the following:
    So, let's say you have kdelibs/ in ~/src/kdelibs/, then do the following:
    <code>
    <syntaxhighlight lang="bash">
    $ ls
    $ ls
    kdelibs/
    kdelibs/
    Line 54: Line 53:
    $ cd kdelibs-build
    $ cd kdelibs-build
    $ cmake ../kdelibs
    $ cmake ../kdelibs
    </code>
    </syntaxhighlight>
    This will generate the Makefiles for building kdelibs/ in kdelibs-build/.
    This will generate the Makefiles for building kdelibs/ in kdelibs-build/.


    Line 61: Line 60:


    So, let's say you have kdelibs\ in c:\daten\kde4, then do the following:
    So, let's say you have kdelibs\ in c:\daten\kde4, then do the following:
    <code>
    <syntaxhighlight lang="dos">
    c:\daten\kde4> cd kdelibs\win
    c:\daten\kde4> cd kdelibs\win
    c:\daten\kde4> cmake
    c:\daten\kde4> cmake
    Line 70: Line 69:
    c:\daten\kde4> cd kdelibs-build
    c:\daten\kde4> cd kdelibs-build
    c:\daten\kde4\kdelibs-build> cmake ..\kdelibs
    c:\daten\kde4\kdelibs-build> cmake ..\kdelibs
    </code>
    </syntaxhighlight>


    This will generate the Makefiles for building kdelibs\ in kdelibs-build\. See [[Projects/KDE_on_Windows|KDE on Windows]] for more informations about compiling KDE on Windows.
    This will generate the Makefiles for building kdelibs\ in kdelibs-build\. See [[Projects/KDE_on_Windows|KDE on Windows]] for more informations about compiling KDE on Windows.
    Line 76: Line 75:
    ==== KDevelop 3 Project Files ====
    ==== KDevelop 3 Project Files ====
    If you prefer project files for KDevelop 3 (which will basically be Makefiles accompanied by some extra files for KDevelop), run it like this:
    If you prefer project files for KDevelop 3 (which will basically be Makefiles accompanied by some extra files for KDevelop), run it like this:
    <code>
    <syntaxhighlight lang="bash">
    $ cmake ../kdelibs -GKDevelop3
    $ cmake ../kdelibs -GKDevelop3
    </code>
    </syntaxhighlight>
    Use 'cmake -h' to find out which generators CMake supports and the other options.
    Use 'cmake -h' to find out which generators CMake supports and the other options.


    Line 98: Line 97:
    Some cmake command line variables you may want to set:
    Some cmake command line variables you may want to set:
    * '''CMAKE_INSTALL_PREFIX''': cmake ../kdelibs -DCMAKE_INSTALL_PREFIX=/opt/kde4 is the equivalent to ./configure --prefix=/opt/kde4
    * '''CMAKE_INSTALL_PREFIX''': cmake ../kdelibs -DCMAKE_INSTALL_PREFIX=/opt/kde4 is the equivalent to ./configure --prefix=/opt/kde4
    * '''[[Development/CMake/Addons_for_KDE#Buildtypes|CMAKE_BUILD_TYPE]]''': decide which type of build you want. You can choose between "debugfull", "Debug", "Profile", "RelWithDebInfo" and "Release". The default is "RelWithDebInfo". Please refer to page [[Development/CMake/Addons_for_KDE#Buildtypes|CMake Build Types]] for a more detailed explanation.
    * '''[[Development/CMake/Addons_for_KDE#Buildtypes|CMAKE_BUILD_TYPE]]''': decide which type of build you want. You can choose between "DebugFull", "Debug", "Profile", "RelWithDebInfo" and "Release". The default is "RelWithDebInfo". Please refer to page [[Development/CMake/Addons_for_KDE#Buildtypes|CMake Build Types]] for a more detailed explanation.
    * '''KDE4_BUILD_TESTS=ON''': creates Makefiles with build test programs and also provides 'test' targets
    * '''KDE4_BUILD_TESTS=ON''': creates Makefiles with build test programs and also provides 'test' targets
    * '''KDE4_TEST_OUTPUT=xml''': Unit tests using the QTestLib framework will create xml formatted logfiles.
    * '''KDE4_TEST_OUTPUT=xml''': Unit tests using the QTestLib framework will create xml formatted logfiles.
    Line 122: Line 121:


    If you got a failure that says something like
    If you got a failure that says something like
    <code>
    <pre>
    CMake Error: This project requires some variables to be set,
    CMake Error: This project requires some variables to be set,
    and cmake can not find them.
    and cmake can not find them.
    Please set the following variables:
    Please set the following variables:
    X11_XTest_LIB (ADVANCED)
    X11_XTest_LIB (ADVANCED)
    </code>
    </pre>
    then you may have a missing library (or other dependency). To find
    then you may have a missing library (or other dependency). To find
    out which library, search in the cmake/modules directory for
    out which library, search in the cmake/modules directory for
    the variable that cmake can't find. In the example above, it is
    the variable that cmake can't find. In the example above, it is
    <code>
    <syntaxhighlight lang="cmake">
    find_library(X11_XTest_LIB Xtst ${X11_LIB_SEARCH_PATH})
    find_library(X11_XTest_LIB Xtst ${X11_LIB_SEARCH_PATH})
    </code>
    </syntaxhighlight>
    So the missing library is Xtst. You then need to find it (perhaps installing a libXtst-devel library) and re-run cmake.
    So the missing library is Xtst. You then need to find it (perhaps installing a libXtst-devel library) and re-run cmake.


    Line 139: Line 138:


    Here's the most simple CMakeLists.txt:
    Here's the most simple CMakeLists.txt:
    <code>
    <syntaxhighlight lang="cmake">
    add_executable(hello main.cpp)
    add_executable(hello main.cpp)
    </code>
    </syntaxhighlight>
    This will create an executable named "hello" (or "hello.exe" under Windows) from the source file main.cpp. You can mix C and C++ files as you want.  You can have multiple executables and libraries in one CMakeLists.txt.  The same source file can be used in multiple targets, it will be compiled for each target independently from the other targets.  Probably the most important part of the cmake language are the variables:
    This will create an executable named "hello" (or "hello.exe" under Windows) from the source file main.cpp. You can mix C and C++ files as you want.  You can have multiple executables and libraries in one CMakeLists.txt.  The same source file can be used in multiple targets, it will be compiled for each target independently from the other targets.  Probably the most important part of the cmake language are the variables:
    <code>
    <syntaxhighlight lang="cmake">
    set( MY_SOURCES main.cpp widget.cpp)
    set( MY_SOURCES main.cpp widget.cpp)
    message(STATUS "my sources: ${MY_SOURCES}")
    message(STATUS "my sources: ${MY_SOURCES}")
    </code>
    </syntaxhighlight>
    So, use the SET() command to set the value of a variable. If you list more than one string, the variable will be a list.  A list is a list of strings separated by semicolons. If you set it to only one item, it will have just that value. To get the value of a variable, use ${VAR}.
    So, use the SET() command to set the value of a variable. If you list more than one string, the variable will be a list.  A list is a list of strings separated by semicolons. If you set it to only one item, it will have just that value. To get the value of a variable, use ${VAR}.
    You can iterate over a list using FOREACH():
    You can iterate over a list using FOREACH():
    <code>
    <syntaxhighlight lang="cmake">
    foreach(next_ITEM ${MY_SOURCES})
    foreach(next_ITEM ${MY_SOURCES})
       message(STATUS "next item: ${next_ITEM}")
       message(STATUS "next item: ${next_ITEM}")
    endforeach(next_ITEM ${MY_SOURCES})
    endforeach(next_ITEM ${MY_SOURCES})
    </code>
    </syntaxhighlight>
    The commands in CMake are case-insensitive.  Names of variables and names of parameter are case-sensitive.
    The commands in CMake are case-insensitive.  Names of variables and names of parameter are case-sensitive.


    You can also test for various things:
    You can also test for various things:
    <code>
    <syntaxhighlight lang="cmake">
    if (UNIX)
    if (UNIX)
       message(STATUS "This is UNIX (including OS X and CygWin)")
       message(STATUS "This is UNIX (including OS X and CygWin)")
    Line 165: Line 164:
       set(MY_SRCS ${MY_SRCS} winextra.cpp)
       set(MY_SRCS ${MY_SRCS} winextra.cpp)
    endif (MSVC)
    endif (MSVC)
    </code>
    </syntaxhighlight>
    In this second example  you can see also how to append items to a list.
    In this second example  you can see also how to append items to a list.


    Line 173: Line 172:


    Here's a basic CMakeList file that builds a small KDE 4 project:
    Here's a basic CMakeList file that builds a small KDE 4 project:
    <code>
    <syntaxhighlight lang="cmake">
    project( kde4project )
    project( kde4project )
    find_package( KDE4 REQUIRED )
    find_package( KDE4 REQUIRED )
    Line 187: Line 186:


    install( TARGETS kde4project  ${INSTALL_TARGETS_DEFAULT_ARGS} )
    install( TARGETS kde4project  ${INSTALL_TARGETS_DEFAULT_ARGS} )
    </code>
    </syntaxhighlight>


    ''target_link_libraries'' contains the development libraries that are linked to your program. E.g. if you want to link to libtidy-devel, your library file name may be called /usr/local/lib/libtidy.a. You would then add -ltidy to a gcc call. Here, you add ''tidy'' to your target_link_libraries. If possible, use pre-defined variables or macros like ${KDE4_KDEUI_LIBS}.
    ''target_link_libraries'' contains the development libraries that are linked to your program. E.g. if you want to link to libtidy-devel, your library file name may be called /usr/local/lib/libtidy.a. You would then add -ltidy to a gcc call. Here, you add ''tidy'' to your target_link_libraries. If possible, use pre-defined variables or macros like ${KDE4_KDEUI_LIBS}.
    Line 202: Line 201:
    == Converting autotools-based KDE software to CMake ==
    == Converting autotools-based KDE software to CMake ==
    In kdesdk/cmake/ you can find a script am2cmake . This is a ruby script, so you need to have ruby installed. Run am2cmake in the toplevel directory of your sources:
    In kdesdk/cmake/ you can find a script am2cmake . This is a ruby script, so you need to have ruby installed. Run am2cmake in the toplevel directory of your sources:
    <code>
    <syntaxhighlight lang="bash">
    $ cd src/mykooltool/
    $ cd src/mykooltool/
    $ am2cmake --kde4
    $ am2cmake --kde4
    </code>
    </syntaxhighlight>
    Don't forget the switch "--kde4", otherwise it won't generate files suitable for KDE 4 software. The converted files 'may' work as they are, but complicated projects will require some additional editing.
    Don't forget the switch <tt>--kde4</tt>, otherwise it won't generate files suitable for KDE 4 software. The converted files 'may' work as they are, but complicated projects will require some additional editing.


    You may have to:
    You may have to:

    Revision as of 15:22, 13 July 2012

    Introduction

    CMake reads script files and produces input files for the native buildsystem of the platform where it runs on. It can create GNU Makefiles, KDevelop project files, XCode project files, and Visual Studio project files.

    CMake is free software and released under a BSD license. It is developed by Kitware Inc.

    You can find more CMake related information on the main CMake page here on TechBase.

    Why use CMake ?

    CMake is the official tool of KDE 4 release, decided in March 2006, primarily due to technical merits as compared to the older KDE tools automake and unsermake:

    • CMake is developed independently of KDE, it can be used by other projects as well
    • Compilation time is much faster, mainly due to not using libtool anymore
    • The build files are easier to write

    How to compile KDE using CMake

    Get and install CMake

    Linux, BSD, and other Unix Systems

    Retrieve the latest stable version of CMake from here.

    Once downloaded, unpack and compile it:

    $ mkdir cmake-build
    $ cd cmake-build
    $ ../bootstrap
    $ make
    $ make install
    

    By default, this will install CMake in /usr/local, so make sure to have /usr/local/bin in your execute path. To change the installation prefix (e.g. to /usr in debian), add the '--prefix=PATH' option to the bootstrap command.

    Please follow the instructions located here if you would like to use the current development version.

    Windows

    Retrieve the latest stable version of CMake from here.

    Once downloaded, run the cmake installer.

    By default, this will install CMake in C:\Program Files\CMake 2.8, so make sure to have <installpath>\bin in your execute path.

    Please follow the instructions at here if you would like to use the current development version.

    Run CMake

    Linux, BSD, and other Unix Systems

    You have to run CMake so that it generates the build files for your system. Both in-source and out-of-source builds are supported by CMake, but currently in-source builds are prevented by the KDE implementation.

    So, let's say you have kdelibs/ in ~/src/kdelibs/, then do the following:

    $ ls
    kdelibs/
    $ mkdir kdelibs-build
    $ cd kdelibs-build
    $ cmake ../kdelibs
    

    This will generate the Makefiles for building kdelibs/ in kdelibs-build/.

    Windows

    You have to run CMake so that it generates the build files for your system. Both in-source and out-of-source builds are supported by CMake, but currently in-source builds are prevented by the KDE implementation.

    So, let's say you have kdelibs\ in c:\daten\kde4, then do the following:

    c:\daten\kde4> cd kdelibs\win
    c:\daten\kde4> cmake
    c:\daten\kde4> make 
    c:\daten\kde4> make install
    c:\daten\kde4> cd ..
    c:\daten\kde4> mkdir kdelibs-build
    c:\daten\kde4> cd kdelibs-build
    c:\daten\kde4\kdelibs-build> cmake ..\kdelibs
    

    This will generate the Makefiles for building kdelibs\ in kdelibs-build\. See KDE on Windows for more informations about compiling KDE on Windows.

    KDevelop 3 Project Files

    If you prefer project files for KDevelop 3 (which will basically be Makefiles accompanied by some extra files for KDevelop), run it like this:

    $ cmake ../kdelibs -GKDevelop3
    

    Use 'cmake -h' to find out which generators CMake supports and the other options.

    CMake and Qt4

    To locate Qt 4, CMake searches for qmake in your execute path. CMake does not use the QTDIR environment variable. So make sure that the first qmake found in the execution path is the one you like to use.

    More Details

    When CMake has finished, it will have created a file called "CMakeCache.txt". This file contains all the settings CMake has detected on your system. If you want to run CMake with another generator or you want CMake to detect everything again, delete this file.

    If CMake didn't find something, but you know it is somewere on your box, you can tell CMake manually where to find it. CMake uses variables to store this information. These variables are cached in the already mentioned file CMakeCache.txt. You have three options to adjust these variables manually:

    • tell CMake the correct value via the command line: cmake ../kdelibs -DNAME_OF_THE_VARIABLE=value
    • use ccmake, which provides a curses based GUI to adjust the CMake variables (run: ccmake ../kdelibs)
    • edit the file CMakeCache.txt directly (not recommended)

    You should run "ccmake ../kdelibs" at least once so that you get an impression which variables CMake uses. Press "T" to see also the "advanced" variables. So, if CMake didn't find something, start ccmake and adjust it manually.

    Command Line Variables

    Some cmake command line variables you may want to set:

    • CMAKE_INSTALL_PREFIX: cmake ../kdelibs -DCMAKE_INSTALL_PREFIX=/opt/kde4 is the equivalent to ./configure --prefix=/opt/kde4
    • CMAKE_BUILD_TYPE: decide which type of build you want. You can choose between "DebugFull", "Debug", "Profile", "RelWithDebInfo" and "Release". The default is "RelWithDebInfo". Please refer to page CMake Build Types for a more detailed explanation.
    • KDE4_BUILD_TESTS=ON: creates Makefiles with build test programs and also provides 'test' targets
    • KDE4_TEST_OUTPUT=xml: Unit tests using the QTestLib framework will create xml formatted logfiles.
    • KDE4_DISABLE_MULTIMEDIA=ON: Build KDE without any multimedia (audio and video) support.
    • BUILD_foo=OFF: disables the build for the project in subdirectory 'foo'.
    • WITH_foo: there are several options, e.g. WITH_CUPS or WITH_Jasper. If you disable them, cmake will not even try to find this package. If it is enabled, cmake will try to find it. If it fails with this, you can still adjust it manually as described above.

    Environment Variables

    If you have headers and libraries installed in non-standard locations that cmake cannot find (e.g., fink on Mac OSX installs to /sw), then populate the environment variable CMAKE_PREFIX_PATH with a list of paths to these locations. When searching for headers, libraries and binaries, CMake will search all the paths in CMAKE_PREFIX_PATH as well as their standard subdirectories ("lib" for libraries, "include" for headers and "bin" for binaries). This can be also very useful e.g. if you install kdesupport to ~/install/kdesupport.

    • CMAKE_PREFIX_PATH, eg. export CMAKE_PREFIX_PATH=/sw

    If you need to further tweak the search behavior, you can additionally set the following environment variables in order to add library, include or binary directories to your search path:

    • CMAKE_INCLUDE_PATH, eg. export CMAKE_PREFIX_PATH=/sw/include
    • CMAKE_LIBRARY_PATH, eg. export CMAKE_LIBRARY_PATH=/sw/lib
    • CMAKE_PROGRAM_PATH, eg. export CMAKE_PROGRAM_PATH=/sw/bin

    For more information on variables, see this cmake.org wiki page

    Going Further

    If cmake finishes with "Generating done" then there was no errors, but if it finishes with "Configuring done" then there was errors that you have to fix. Once cmake finishes successfully, run your buildtool (i.e. make, KDevelop, XCode or MSVC) and build and wait until it has finished. Then "make install".

    If you got a failure that says something like

    CMake Error: This project requires some variables to be set,
    and cmake can not find them.
    Please set the following variables:
    X11_XTest_LIB (ADVANCED)
    

    then you may have a missing library (or other dependency). To find out which library, search in the cmake/modules directory for the variable that cmake can't find. In the example above, it is

    find_library(X11_XTest_LIB Xtst ${X11_LIB_SEARCH_PATH})
    

    So the missing library is Xtst. You then need to find it (perhaps installing a libXtst-devel library) and re-run cmake.

    Using CMake for a Simple Application

    Here's the most simple CMakeLists.txt:

    add_executable(hello main.cpp)
    

    This will create an executable named "hello" (or "hello.exe" under Windows) from the source file main.cpp. You can mix C and C++ files as you want. You can have multiple executables and libraries in one CMakeLists.txt. The same source file can be used in multiple targets, it will be compiled for each target independently from the other targets. Probably the most important part of the cmake language are the variables:

    set( MY_SOURCES main.cpp widget.cpp)
    message(STATUS "my sources: ${MY_SOURCES}")
    

    So, use the SET() command to set the value of a variable. If you list more than one string, the variable will be a list. A list is a list of strings separated by semicolons. If you set it to only one item, it will have just that value. To get the value of a variable, use ${VAR}. You can iterate over a list using FOREACH():

    foreach(next_ITEM ${MY_SOURCES})
       message(STATUS "next item: ${next_ITEM}")
    endforeach(next_ITEM ${MY_SOURCES})
    

    The commands in CMake are case-insensitive. Names of variables and names of parameter are case-sensitive.

    You can also test for various things:

    if (UNIX)
       message(STATUS "This is UNIX (including OS X and CygWin)")
    endif (UNIX)
    
    if (MSVC)
       set(MY_SRCS ${MY_SRCS} winextra.cpp)
    endif (MSVC)
    

    In this second example you can see also how to append items to a list.

    In the cmake Wiki there is also a tutorial on using cmake to build KDE 4 software. It is recommended reading.

    Using CMake for a KDE Project

    Here's a basic CMakeList file that builds a small KDE 4 project:

    project( kde4project )
    find_package( KDE4 REQUIRED )
    include(KDE4Defaults)
    
    include_directories( ${KDE4_INCLUDES} )
    
    set( KDE4ProjectSources kde4mainapp.cpp someclass.cpp someotherclass.cpp )
    
    kde4_add_executable( kde4project ${KDE4ProjectSources} )
    
    target_link_libraries( kde4project ${KDE4_KDEUI_LIBS} ${KDE4_KPARTS_LIBS} )
    
    install( TARGETS kde4project  ${INSTALL_TARGETS_DEFAULT_ARGS} )
    

    target_link_libraries contains the development libraries that are linked to your program. E.g. if you want to link to libtidy-devel, your library file name may be called /usr/local/lib/libtidy.a. You would then add -ltidy to a gcc call. Here, you add tidy to your target_link_libraries. If possible, use pre-defined variables or macros like ${KDE4_KDEUI_LIBS}.

    install (TARGETS is where the target will finally be installed. If you do not have this line, make install will not be available.

    Variables, macros and other useful information specific to KDE can be found at the CMake addons for KDE page.

    Extending CMake

    CMake can be extended using cmake scripts. CMake comes with a number of scripts; under UNIX they are by default installed to /usr/local/share/CMake/Modules/. The KDE libraries install also a set of cmake modules into share/apps/cmake/modules/. The files located there will be preferred over the ones in the system global cmake module path. For detecting software packages there are FindFOO.cmake files, see here for more information. You can also write macros in CMake. They are powerful enough to do most things you will need to build software, but they are not intended to be used as a general purpose programming language.

    Converting autotools-based KDE software to CMake

    In kdesdk/cmake/ you can find a script am2cmake . This is a ruby script, so you need to have ruby installed. Run am2cmake in the toplevel directory of your sources:

    $ cd src/mykooltool/
    $ am2cmake --kde4
    

    Don't forget the switch --kde4, otherwise it won't generate files suitable for KDE 4 software. The converted files 'may' work as they are, but complicated projects will require some additional editing.

    You may have to:

    • add more include direcories, using INCLUDE_DIRECTORIES()
    • add more link libraries, using TARGET_LINK_LIBRARIES()
    • add some compile switches, using ADD_DEFINITIONS()
    • add some "configure" checks, see How To Do Platform Checks and How To Find Installed Software
    • take special care of former libtool convenience libraries. They are not supported by cmake, instead there will be a file ConvenienceLibs.cmake created. In this file you will find for every convenience lib a variable, which contains all source files of this convenience lib. For the targets which linked to this convenience lib, just add the variable to the sources.
    • a file AdditionalInfo.txt will be created. There you will see all *.in and *.in.in files of your project. The stuff done in these files will have to be converted manually to cmake.