What is libpurple?

libpurple is intended to be the core of an IM program. When using libpurple, you'll basically be writing a UI for this core chunk of code. Pidgin is a GTK+ frontend to libpurple, Finch is an ncurses frontend, and Adium is a Cocoa frontend.

How does it work?

You write a program in C or C++ that provides all the fancy windows and dialogs and anything that the user interacts with. Your program uses our libpurple library to connect to the IM networks, manage accounts and preferences, and lots of other helpful little things.

Your program registers a bunch of callback functions, called "UI ops," with libpurple. This is done by populating the appropriate uiops structures (eg. PurpleAccountUiOps?, PurpleBlistUiOps?, etc.) and making them available to the libpurple core (by calling purple_account_set_ui_ops, purple_blist_set_ui_ops, etc.). Thes ui ops are triggered by specific events. For example, the buddylist ui ops are used to update your buddylist window when a new buddy is added, or if a buddy goes away, or becomes idle, etc. The same thing happens for conversations, logging etc.

While the uiops are sufficient for most of the ui operations, it's likely that you will want to use various libpurple signals, as well.

Can you give me some details?

Your application will first initialize the core (purple_core_init), add plugin-search paths, load the saved plugins, prefs etc. Your best bet is to check out a copy of the source code and look at finch/finch.c:init_libpurple().

Is it threaded?

Nope! libpurple uses the glib mainloop to do all the things. It watches socket for new data and calls timeout functions after a specified delay. It's easiest if your application also uses the glib mainloop, but this is not required.