Development/Tutorials/Icons: Difference between revisions

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      '''kde4_install_icons( ${ICON_INSTALL_DIR} )'''
      '''kde4_install_icons( ${ICON_INSTALL_DIR} )'''
    = How to test it =
    rm /usr/local/share/icons/hicolor/22x22/apps/krep.png
    rm -rf /var/tmp/kdecache-''user''/

    Revision as of 12:25, 28 August 2011

    Template:Stub

    When trying to add an icon to your program, you will realize there is a lot of wording against common sense. You will see the classes, KIconLoader, KIconEngine, QIconEngine, QIcon and KIcon that all seem to mean the same thing, an icon.

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

    # 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
    [...]
    

    If you have a KDE project and want to use icons within it, and want that these icons install 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} )
    

    How to test it

    rm /usr/local/share/icons/hicolor/22x22/apps/krep.png 
    rm -rf /var/tmp/kdecache-user/