plugins/HOWTO

Everything in this file should be considered old and potentially out of
date.  For more reliable information, install doxygen and graphiz dot, 
then run 
make docs
in the gaim source tree. This will produce html docs in gaim/docs/html 
that will provide an api reference and in the related pages section, 
information on perl and c plugins. 


Ok, this howto is going to be really short and sweet and to the point.

First off, before you do anything else, in all of the files for your plugin,
put the lines

#define GAIM_PLUGINS
#include "gaim.h"

I mean this. Without this, all kinds of things will not work correctly. If you
really want to know exactly what this does, read ../src/gaim.h and learn. But
if you don't want to do that, just know that it's important.

Now that you've put that there, make sure gaim.h is in your include path.

Ok, now you're ready to write the plugin.

The only function that is required is gaim_plugin_init(GModule *). This gets
called as soon as it gets loaded (sort of - man dlopen for more details). If
your function never returns, it will crash gaim! If your plugin uses up all
the memory in the system, it will crash gaim! Once your plugin gets loaded,
it effectively becomes a part of gaim, and anything that goes wrong will look
like it is a problem with gaim itself. I write bugfree code! :) Therefore, it
is your problem, not mine. (I'm usually nice and willing to help you with your
problems though.)

The GModule* that gets passed to gaim_plugin_init is the handle for the plugin.
DO NOT CHANGE THIS POINTER! Bad things will happen. You've been warned. It's
needed for connecting to signals and things. It's a good idea to remember it
somehow.

gaim_plugin_init should return a char*. If the char* returned is not NULL, it
is interpreted as an error, and used as an error message. See the ChangeLog
file in this directory for more details.

You can basically do anything you want in the plugin. You can make function
calls, change public widgets, display new widgets, things like that. But the
really neat thing is you can do things at events. For example, when one of
your buddies signs on, you can instantly send them a message. You can modify
the incoming and outgoing text. You can do all kinds of crazy things. Whatever
you want. Check out SIGNALS for more information.

Plugins can share globals with gaim, but will not share with other plugins.
This is so if you have a global variable GtkWidget *window in your plugin and
J. Random Hacker also has the same name on a global variable, you won't be
constantly overwriting each others' variables. Unfortunately, this also means
that plugins will have difficulty working together. But then again, that's
what shared memory is for.

Plugins can be configured. This makes it so they don't have to be recompiled
in order to change things internal to them, and it's also just a cool feature
to have :). It's optional; to allow your plugin to be configured, add a
function called gaim_plugin_config(). The advised course of action is to have
it pop up a dialog window; but it's your plugin.

When your plugin gets unloaded, gaim will try to call gaim_plugin_remove(). It
doesn't have to be there, but it's nice if, say, you create a window, and when
the plugin gets unloaded, it removes the window. Also, all the callbacks you
have attached to gaim signals will be removed.

Plugins can also unload themselves. To do this, call gaim_plugin_unload(GModule *)
(the GModule* is the handle passed to gaim_plugin_init). When your plugin gets
unloaded, gaim will remove all of your callbacks. It will not call your
gaim_plugin_remove function, however, since it will assume you have already
done the necessary cleanup.

Compilation of the plugins is fairly straight-forward; there is a Makefile in
this directory that has a rule for making the .so file from a .c file. No
modification of the Makefile should be necessary, unless if you simply want
to type 'make' to have it made; otherwise, 'make filename.so' will take
filename.c and make the .so plugin from it. If you need to link in with extra
libraries, you can set the environment variable PLUGIN_LIBS to be the libraries
you want to link with.

There are a few examples in this directory. Enjoy.