Development/Tutorials/Icons

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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} )