Development/Tutorials/Icons

    From KDE TechBase
    Warning
    This page needs a review and probably holds information that needs to be fixed.

    Parts to be reviewed:

    Port to KF5

    When you create your own KDE application you will probably want icons in it like this:

    These icons are called KIcons. This article shows you how to do this using the software krep as an example. In case of a CMake-based project you will need to

    How to use icons in QMake-based projects is discussed elsewhere.

    Your KDE project

    If you have a KDE project and want to use icons within it, and want these icons installed seamlessly, you will have to name the icons after the project. In the following we look at a project named krep. The important lines in CMakeLists.txt are the ones printed bold below:

    PROJECT( krep )
    FIND_PACKAGE( KDE4 REQUIRED )
    INCLUDE_DIRECTORIES( ${KDE4_INCLUDES} . )
     
    SET( krepSources main.cpp krep.cpp krep.h )
     
    qt4_add_dbus_adaptor( krepSources 
                          org.kde.krep.xml
                          krep.h
                          krep
                          mainadaptor
                          MainAdaptor )
     
    kde4_add_ui_files( krepSources krepui.ui )
     
    kde4_add_app_icon( krepSources "hi*-app-krep.png" )
     
    KDE4_ADD_EXECUTABLE( krep ${krepSources} )
     
    TARGET_LINK_LIBRARIES( krep ${KDE4_KPARTS_LIBS} )
     
    install( TARGETS krep ${INSTALL_TARGETS_DEFAULT_ARGS} )
     
    kde4_install_icons( ${ICON_INSTALL_DIR} )
    

    Weitere Informationen:

    How to test it

    The easy way is to define a custom cmake install prefix where you can simply insall the project without touching your system. Use following commands to setup this:

    cd build
    cmake -DCMAKE_INSTALL_PREFIX=$HOME/playground ../
    make && make install
    

    now the files should be deployed under

    $HOME/playground/bin/krep
    $HOME/playground/share/apps/krep
    $HOME/playground/share/icons/hicolor/22x22/apps/krep.png
    

    With this method you can easy see what you will get.

    Note
    You can still not see the icon in your application because $HOME/playground is not a know path by kde.

    Normaly kde support a user defined space under $HOME/.kde.

    Find out if this is supported with the command

    kde4-config -path icon
    

    finally you have to extend the search path for kde

    export KDEDIRS=$KDEDIRS:$HOME/playground
    


    The icon naming scheme

    Example for icon names:

    • hisc-apps-bla.svgz will be installed e.g. to /usr/local/share/icons/hicolor/scalable/apps/bla.svgz. hi stands for "hicolor", sc for "scalable", apps for "applications", bla for the application's name and .svgz is the suffix for gzipped scalable vector graphic files.
    • hi128-apps-ktimetracker.png will be installed e.g. to /usr/share/icons/hicolor/128x128/apps/ktimetracker.png. hi stands for "hicolor", 128 for a resolution of 128x128 pixels, apps for "applications", ktimetracker for the application's name and .png is the suffix for portable network graphic files.

    example application

    In this chapter we will build - on top of the KAction example - an example application kicons that looks like this:

    You can obtain its source code as part of kdeexamples by calling

    git clone git://anongit.kde.org/kdeexamples
    

    files

    The example application consists of

    just taken from the KAction example
    Note the command
    clearAction->setIcon(KIcon("tutorial-kicon"));
    
    that sets the icon
    just taken from the KAction example
    This is a file that defines our icon in (almost natural) english language. It is a scalable vector graphic file. Before being used, it must be converted into a zipped scalable vector graphic named hisc-apps-tutorial-kicon.svgz, see below.
    just taken from the KAction example
    sorry for the name, but there are naming conventions. Create this file with the convert command from the ImageMagick package
    convert world.svg hisc-apps-tutorial-kicon.svgz
    
    Note the commands
    kde4_install_icons(${ICON_INSTALL_DIR})
    
    and
    kde4_update_iconcache()
    
    which integrate the icons.

    build it

    To compile, link and install the example application, do a

    mkdir build && cd build
    cmake ../ && make && make install
    

    To run it, call

    tutorial-kicon
    

    Analyzing the KApplications

    Maybe you have already searched for yourself how a KDE application finds its icons. You will not be successful like this:

     # [http://www.linuxintro.org/wiki/Strace#Search_for_a_syscall strace -e open] ktimetracker 2>&1 | grep icon
     open("/usr/lib64/libkemoticons.so.4", O_RDONLY) = 3
     #
    

    You see, a KDE application (in this case ktimetracker) does not open icon files or even look for them. However, it spawns a process to look for these icons:

     linux-qgla:~/repos/kdepim/ktimetracker # strace -ffe open ktimetracker 2>&1 | grep icon
     open("/usr/lib64/libkemoticons.so.4", O_RDONLY) = 3
     [pid  3457] open("/root/.icons/DMZ/cursors/left_ptr", O_RDONLY) = -1 ENOENT (No such file or directory)
     [pid  3457] open("/root/.icons/DMZ/index.theme", O_RDONLY) = -1 ENOENT (No such file or directory)
     [pid  3457] open("/usr/share/icons/DMZ/cursors/left_ptr", O_RDONLY) = 10
     [pid  3457] open("/var/tmp/kdecache-root/icon-cache.kcache", O_RDWR|O_CREAT|O_CLOEXEC, 0666) = 10
     [pid  3457] open("/var/tmp/kdecache-root/kpc/kde-icon-cache.data", O_RDONLY|O_CLOEXEC) = 10
     [pid  3457] open("/var/tmp/kdecache-root/kpc/kde-icon-cache.index", O_RDONLY|O_CLOEXEC) = 10
     [...]
    

    Moving On

    Now you can move on to how to place your application in the K-Menu using .desktop files.