Change Elementary OS Lock Screen Background With Vala and User Specific

Question

I've been trying to change the background image of pantheon-greeter. It should change on the depending user. After browsing the code base of pantheon greeter if found that they get the background image from the method LightDM.User.get_background (). Is that the right way? If it is so how can I change the user specific background with Vala?

Answer 1

I've found a solution in the official code of the elementary settings app.

[DBus (name = "org.freedesktop.Accounts.User")]
    interface AccountsServiceUser : Object {
    public abstract void set_background_file (string filename) throws IOError;
}

Define Dbus and declare the private member on your class

//Instance of the AccountsServices-Interface for this user
private AccountsServiceUser accountsservice = null;

and the implementation

try {
        string uid = "%d".printf ((int) Posix.getuid ());
        accountsservice = Bus.get_proxy_sync (BusType.SYSTEM,
                "org.freedesktop.Accounts",
                "/org/freedesktop/Accounts/User" + uid);
    } catch (Error e) {
        warning (e.message);
    }

is actually what is needed. So you can call

accountsservice.set_background_file (path);

For more information about the implementation look in the source of the switchboard project of Elementary at launchpad