This tutorial is for people who are using Debian, and want to start developing, but the task of setting up an environment seems a bit too much trouble at first sight. The tutorial is not meant to be a standard way of doing things but it is nice to start with.
First you need to add the source repositories to your installation. This is normally done by editing "/etc/apt/sources.list" and adding a line starting with "deb-src". The easy way is to copy your existing "deb" line onto a new line, and change "deb" to "deb-src". In most of the cases this will work. Then you must let this change know to the package manager, so do as root "aptitude update".
Now you want to be able to build a certain package, and in this example we will build kcontrol and systemsettings so we can fix some bug in the "Display" configuration module, which is called "randr". In debian the package is "systemsettings", so we get the build dependencies of that package, so do as root "aptitude build-dep systemsettings". This will download and install all needed dependencies which are mostly packages with "-dev" at the end of them, which are a bunch of header files most of the time.
Now in your home directory, make a new directory, and go into it:
karel@pc:/home/karel # mkdir kde4devel karel@pc:/home/karel # cd kde4devel
Now we get the sources in this directory, as root, do:
karel@pc:/home/karel/kde4devel # su root@pc:/home/karel/kde4devel # apt-get source systemsettings
This downloads the source and applies all the debian patches. In this case, it downloads "kdebase-workspace" because the systemsettings code is only a small part of the kdebase-workspace package. Now go into the newly extracted directory . This is now "kdebase-workspace-4.3.2" in my case.
Now we go into the source directory, and let "cmake" generate the Makefiles, which are then used by the "make" command to build the code. But first we change the owner from root back to our user "karel". This is done like this:
root@pc:/home/karel/kde4devel/kdebase-workspace-4.3.2 # chown -R karel.karel ../* root@pc:/home/karel/kde4devel/kdebase-workspace-4.3.2 # exit karel@pc:/home/karel/kde4devel/kdebase-workspace-4.3.2 # cmake . karel@pc:/home/karel/kde4devel/kdebase-workspace-4.3.2 # cmake-gui .
Now select only the components starting with "BUILD_" you want. In my case it was rather the components I'm sure of that I don't want :). So I ended up with only BUILD_kcontrol and systemsettings. Then click on the "Configure" button and then on the "Generate" button. Close the program now. Now we have makefiles for everything we want to build. So now do the make command to build what we have selected:
karel@pc:/home/karel/kde4devel/kdebase-workspace-4.3.2 # make
Now it is built!
To run our module, we go to the directory of the randr module. There we tell it to do a "make install" as root. This will install the needed files to /usr/local.
root@pc:/home/karel/kde4devel/kdebase-workspace-4.3.2/kcontrol/randr# make install
We need to tell our current session the additional KDE path where it needs to look for services and libraries and programs. This is done by filling in the KDEDIRS environment variable like this:
karel@pc:/home/karel/kde4devel/kdebase-workspace-4.3.2/kcontrol/randr # export KDEDIRS=/usr/local
Then we start the randr module like this:
karel@pc:/home/karel/kde4devel/kdebase-workspace-4.3.2/kcontrol/randr # ./krandrtray
This starts the tray icon which find the kcm module "randr" first in the KDEDIRS location, so this one is loaded. If you start the systemsettings program, it also loads in the same way the kcm config module in /usr/local. So this depends on the KDEDIRS variable, without it, the randr module found in the default debian location is used!
So now you can change something in the code, run "make" and then "make install" as root(or "sudo make install") in the correct directory, and you can test the program out.