Updating NEWS-file a bit with recent changes done by frlan

[geany-mirror.git] / doc / plugins.dox

/*
 *      plugins.dox - this file is part of Geany, a fast and lightweight IDE
 *
 *      Copyright 2008-2011 Enrico Tröger <enrico(dot)troeger(at)uvena(dot)de>
 *      Copyright 2008-2011 Nick Treleaven <nick(dot)treleaven(at)btinternet(dot)com>
 *      Copyright 2009-2012 Frank Lanitz <frank(at)frank(dot)uvena(dot)de>
 *
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation; either version 2 of the License, or
 *      (at your option) any later version.
 *
 *      This program is distributed in the hope that it will be useful,
 *      but WITHOUT ANY WARRANTY; without even the implied warranty of
 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *      GNU General Public License for more details.
 *
 *      You should have received a copy of the GNU General Public License along
 *      with this program; if not, write to the Free Software Foundation, Inc.,
 *      51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * This file contains additional plugin documentation like the signal system and a small howto.
 * It is best viewed when filetype is set to C or C++.
 */


/**
 *
 * @mainpage Geany Plugin API Documentation
 *
 * @author Enrico Tröger, Nick Treleaven, Frank Lanitz
 *
 * @section Intro
 * This is the Geany API documentation. It should be considered work in progress.
 * We will try to document as many functions and structs as possible.
 *
 * @warning Do not use any symbol not in the documentation - it may change.
 *
 * @section pluginsupport Plugin Support
 * - @link howto Plugin HowTo @endlink - get started
 * - @link pluginsymbols.c Plugin Symbols @endlink
 * - @link plugindata.h Plugin Datatypes and Macros @endlink
 * - @link pluginsignals.c Plugin Signals @endlink
 * - @link pluginutils.h Plugin Utility Functions @endlink
 * - @link guidelines Plugin Writing Guidelines @endlink
 * - <b>plugins/demoplugin.c</b> - in Geany's source, bigger than the howto example
 *
 * @section common Common API files
 * - @link dialogs.h @endlink
 * - @link document.h @endlink
 * - @link editor.h @endlink
 * - @link filetypes.h @endlink
 * - @link keybindings.h @endlink
 * - @link msgwindow.h @endlink
 * - @link project.h @endlink
 * - @link sciwrappers.h Scintilla Wrapper Functions @endlink
 * - @link stash.h Stash Pref/Setting Functions @endlink
 * - @link utils.h General Utility Functions @endlink
 * - @link ui_utils.h Widget Utility Functions @endlink

 * @section More
 * - All API functions and types - see <b>Files</b> link at the top
 * - Deprecated symbols - see <b>Related Pages</b> link at the top
 *
 * @note See the HACKING file for information about developing the plugin API and
 * other useful notes.
 */

/**
 *  @page guidelines Plugin Writing Guidelines
 *
 *  @section intro Introduction
 *
 *  The following hints and guidelines are only recommendations. Nobody is forced to follow
 *  them at all.
 *
 *  @section general General notes
 *
 *  @subsection ideas Getting a plugin idea
 *
 *  If you want to write a plugin but don't know yet what it should do, have a look at
 *  http://www.geany.org/Support/PluginWishlist to get an idea about what users wish.
 *
 *  @subsection code Managing the source code
 *
 *  For authors of plugins for Geany, we created a dedicated @a geany-plugins project
 *  on Sourceforge and GitHub to ease development of plugins and help new authors.
 *  All information about this project you can find at http://plugins.geany.org/
 *
 *  To add a new plugin to this project, get in touch with the people on the
 *  geany-devel-mailing list and create a fork of the geany-plugins project
 *  at https://github.com/geany/geany-plugins.
 *  Beside of adding a new plugin, geany-devel-mailing list is also the place where
 *  to discuss development related questions.
 *  However, once you have done your fork of geany-plugins you can develop
 *  your plugin until you think its the right time to publish it. At this point,
 *  create a pull request for adding your patch set into the master branch of the main
 *  geany-plugins repository.
 *
 *  Of course, you don't need to use GitHub - any Git is fine. But GitHub
 *  is making it way easier for review, merging and get in touch with you for 
 *  comments.
 *
 *  If you don't want your plugin to be part of the geany-plugins project it is also fine.
 *  Just skip the part about forking geany-plugins and sending a pull request.
 *  In this case it is of course also a good idea to post some kind of announcement
 *  to geany-devel and maybe to the main geany mailing list -- it's up to you.
 *  You can also ask for your plugin to be listed on the http://plugins.geany.org/
 *  website as a third party plugin, helping Geany user to know about your plugin.
 *
 *  At time of writing, there are some plugins already available in the
 *  repositories. Feel free to use any of these plugins as a start for your own,
 *  maybe by copying the directory structure and the autotools files
 *  (Makefile.am, configure.in, ...). Most of the available plugins are also ready for
 *  i18n support, just for reference.
 *
 *  We encourage authors using this service to only commit changes to their
 *  own plugin and not to others' plugins. Instead just send patches to
 *  geany-devel at uvena.de or the plugin author directly.
 *
 *  @section paths Installation paths
 *
 *   - The plugin binary (@c pluginname.so) should be installed in Geany's libdir. This is
 *     necessary so that Geany can find the plugin.
 *     An easy way to retrieve Geany's libdir is to use the pkg-config tool, e.g. @code
 *     `$PKG_CONFIG --variable=libdir geany`/ geany
 *     @endcode
 *   - If your plugin creates other binary files like helper programs or helper libraries,
 *     they should go into @c $prefix/bin (for programs, ideally prefixed with @a geany),
 *     additional libraries should be installed in Geany's libdir, maybe in a subdirectory.
 *   - Plugins should install their documentation files (README, NEWS, ChangeLog, licences and
 *     other documentation files) into the common documentation directory
 *     @c $prefix/share/doc/geany-plugins/$pluginname/
 *   - Translation files should be installed normally into @c $prefix/share/locale. There is no
 *     need to use Geany's translation directory. To set up translation support properly and
 *     for additional information, see main_locale_init().
 *   - Do @a never install anything into a user's home directory like installing
 *     the plugin binary in @c ~/.config/geany/plugins/.
 *
 *
 *  @page howto Plugin HowTo
 *
 *  @section intro Introduction
 *
 *  Since Geany 0.12 there is a plugin interface to extend Geany's functionality and
 *  add new features. This document gives a brief overview about how to add new
 *  plugins by writing a simple "Hello World" plugin in C or C++.
 *
 *
 *  @section buildenv Build environment
 *
 *  To be able to write plugins for Geany, you need the source code and some development
 *  packages for GTK and its dependencies. The following will only describe the way to compile and
 *  build plugins on Unix-like systems [1].
 *  If you already have the Geany source code and compiled it from them, you can skip the
 *  following.
 *
 *  First you need to have Geany installed. Then install the development files for GTK
 *  and its dependencies. The easiest way to do this is to use your distribution's package
 *  management system, e.g. on Debian and Ubuntu systems you can use
 *  @code apt-get install libgtk2.0-dev intltool @endcode
 *  This will install all necessary files to be able to compile plugins for Geany. On other
 *  distributions, the package names and commands to use may differ.
 *
 *  Basically, you are done at this point and could continue with writing the plugin code.
 *
 *  [1] For Windows, it is basically the same but you might have some more work on setting up
 *  the general build environment(compiler, GTK development files, ...). This is described on
 *  Geany's website at http://www.geany.org/Support/BuildingOnWin32.
 *
 *  @section helloworld "Hello World"
 *
 *  When writing a plugin, you will find a couple of functions or macros which are mandatory
 *  and some which are free to use for implementing some useful feature once your plugin
 *  becomes more powerful like including a configuration or help dialog.
 *
 *  You should start your plugin with including some of the needed C header files and defining
 *  some basic global variables which will help you to access all needed functions of the plugin
 *  API in a more comfortable way.
 *
 *  Let's start with the very basic headers and add more later if necessary.
 *  @code
#include <geanyplugin.h>
 *  @endcode
 *
 *  @a geanyplugin.h includes all of the Geany API and also the necessary GTK header files,
 *  so there is no need to include @a gtk/gtk.h yourself.
 *
 *  @note
 *  @a plugindata.h contains the biggest part of the plugin API and provides some basic macros.
 *  @a geanyfunctions.h provides some macros for convenient access to plugin API functions.
 *
 *  Then you should define three basic variables which will give access to data fields and
 *  functions provided by the plugin API.
 *  @code
GeanyPlugin                     *geany_plugin;
GeanyData                       *geany_data;
GeanyFunctions          *geany_functions;
 *  @endcode
 *
 *  Now you can go on and write your first lines for your new plugin. As mentioned before,
 *  you will need to implement and fill out a couple of functions/macros to make the plugin work.
 *  So let's start with PLUGIN_VERSION_CHECK().
 *
 *  PLUGIN_VERSION_CHECK() is a convenient way to tell Geany which version of Geany's plugin API
 *  is needed at minimum to run your plugin. The value is defined in
 *  @a plugindata.h by @a GEANY_API_VERSION. In most cases this should be your minimum.
 *  Nevertheless when setting this value, you should choose the lowest possible version here to
 *  make the plugin compatible with a bigger number of versions of Geany.
 *
 *  For the next step, you will need to tell Geany some basic information about your plugin
 *  which will be shown in the plugin manager dialog.
 *
 *  To do this you should use the PLUGIN_SET_INFO() macro, which expects 4 parameters:
 *  - Plugin name
 *  - Short description
 *  - Version
 *  - Author
 *
 *  Based on this, the line could look like:
 *  @code
PLUGIN_SET_INFO("HelloWorld", "Just another tool to say hello world",
                                "1.0", "John Doe <john.doe@example.org>");
 *  @endcode
 *
 *  Once this is done, you will need to implement the function which will be executed when the
 *  plugin is loaded. Part of that function could be adding and removing of an item to
 *  Geany's Tools menu, setting up keybindings or registering some callbacks. Also you will
 *  need to implement the function that is called when your plugin is unloaded.
 *  These functions are called plugin_init() and plugin_cleanup(). Let's see what this
 *  looks like:
 *  @code
PLUGIN_VERSION_CHECK(211)

PLUGIN_SET_INFO("HelloWorld", "Just another tool to say hello world",
                                "1.0", "Joe Doe <joe.doe@example.org>");

void plugin_init(GeanyData *data)
{
}

void plugin_cleanup(void)
{
}
 *  @endcode
 *
 *  If you think this plugin seems not to implement any functionality right now and only wastes
 *  some memory, you are right. But it should compile and load/unload in Geany nicely.
 *  Now you have the very basic layout of a new plugin. Great, isn't it?
 *
 *  @note
 *
 *  If you would rather write the plugin in C++, you can do that by marking the
 *  plugin functions that it implements as @c extern @c "C", for example:
 *
 *  @code
 *
extern "C" void plugin_init(GeanyData *data)
{
}

extern "C" void plugin_cleanup(void)
{
}
 *  @endcode
 *
 *  @section building Building
 *
 *  First make plugin.o:
 *
 *  @code gcc -c plugin.c -fPIC `pkg-config --cflags geany` @endcode
 *
 *  Then make the plugin library plugin.so (or plugin.dll on Windows):
 *
 *  @code gcc plugin.o -o plugin.so -shared `pkg-config --libs geany` @endcode
 *
 *  If all went OK, put the library into one of the paths Geany looks for plugins,
 *  e.g. $prefix/lib/geany. See @ref paths "Installation paths" for details.
 *
 *  @note
 *
 *  If you are writing the plugin in C++, then you will need to use your C++
 *  compiler here, for example @c g++.
 *
 *  @section realfunc Adding functionality
 *
 *  Let's go on and implement some real functionality.
 *
 *  As mentioned before, plugin_init() will be called when the plugin is loaded in Geany.
 *  So it should implement everything that needs to be done during startup. In this case,
 *  we'd like to add a menu item to Geany's Tools menu which runs a dialog printing "Hello World".
 *  @code
void plugin_init(GeanyData *data)
{
        GtkWidget *main_menu_item;

        // Create a new menu item and show it
        main_menu_item = gtk_menu_item_new_with_mnemonic("Hello World");
        gtk_widget_show(main_menu_item);

        // Attach the new menu item to the Tools menu
        gtk_container_add(GTK_CONTAINER(geany->main_widgets->tools_menu),
                main_menu_item);

        // Connect the menu item with a callback function
        // which is called when the item is clicked
        g_signal_connect(main_menu_item, "activate",
                G_CALLBACK(item_activate_cb), NULL);
}
 *  @endcode
 *
 *  This will add an item to the Tools menu and connect this item to a function which implements
 *  what should be done when the menu item is activated by the user.
 *  This is done by g_signal_connect(). The Tools menu can be accessed with
 *  geany->main_widgets->tools_menu. The structure @a main_widgets contains pointers to the
 *  main GUI elements in Geany.
 *
 *  Geany has a simple API for showing message dialogs. So our function contains
 *  only a few lines:
 *  @code
void item_activate_cb(GtkMenuItem *menuitem, gpointer user_data)
{
        dialogs_show_msgbox(GTK_MESSAGE_INFO, "Hello World");
}
 *  @endcode
 *
 *  For the moment you don't need to worry about the parameters of that function.
 *
 *  Now we need to clean up properly when the plugin is unloaded.
 *
 *  To remove the menu item from the Tools menu, you can use gtk_widget_destroy().
 *  gtk_widget_destroy() expects a pointer to a GtkWidget object.
 *
 *  First you should add gtk_widget_destroy() to your plugin_cleanup() function.
 *  The argument for gtk_widget_destroy() is the widget object you created earlier in
 *  plugin_init(). To be able to access this pointer in plugin_cleanup(), you need to move
 *  its definition from plugin_init() into the global context so its visibility will increase
 *  and it can be accessed in all functions.
 *  @code
static GtkWidget *main_menu_item = NULL;

// ...
void plugin_init(GeanyData *data)
{
        main_menu_item = gtk_menu_item_new_with_mnemonic("Hello World");
        gtk_widget_show(main_menu_item);
// ...
}

void plugin_cleanup(void)
{
        gtk_widget_destroy(main_menu_item);
}
 *  @endcode
 *
 *  This will ensure your menu item is removed from the Tools menu as well as from
 *  memory once your plugin is unloaded, so you don't leave any memory leaks.
 *  Once this is done, your first plugin is ready. Congratulations!
 *
 *  @section listing Complete listing (without comments)
 *
 *  @code
#include <geanyplugin.h>

GeanyPlugin             *geany_plugin;
GeanyData               *geany_data;
GeanyFunctions  *geany_functions;

PLUGIN_VERSION_CHECK(211)

PLUGIN_SET_INFO("HelloWorld", "Just another tool to say hello world",
                                "1.0", "John Doe <john.doe@example.org>");


static GtkWidget *main_menu_item = NULL;

static void item_activate_cb(GtkMenuItem *menuitem, gpointer gdata)
{
        dialogs_show_msgbox(GTK_MESSAGE_INFO, "Hello World");
}

void plugin_init(GeanyData *data)
{
        main_menu_item = gtk_menu_item_new_with_mnemonic("Hello World");
        gtk_widget_show(main_menu_item);
        gtk_container_add(GTK_CONTAINER(geany->main_widgets->tools_menu),
                main_menu_item);
        g_signal_connect(main_menu_item, "activate",
                G_CALLBACK(item_activate_cb), NULL);
}

void plugin_cleanup(void)
{
        gtk_widget_destroy(main_menu_item);
}
 *  @endcode
 *
 *
 * Now you might like to look at Geany's source code for core plugins such as
 * @a plugins/demoplugin.c.
 *
 * @section furtherimprovements Furter Improvements and next steps
 * @subsection translatable_plugin_information Translatable plugin information
 *
 * After having written our first plugin, there is still room for improvement.
 *
 * By default, PLUGIN_SET_INFO() does not allow translation of the basic plugin
 * information for plugins which are not shipped with Geany's core distribution.
 * Since most plugins are not shipped with Geany's core, it makes sense to
 * enable translation when the plugin is loaded so that it gets translated
 * inside Geany's Plugin Manager.  As of Geany 0.19, the plugin API contains
 * the PLUGIN_SET_TRANSLATABLE_INFO() macro which enables translation of the
 * basic plugin details passed to PLUGIN_SET_INFO() when the plugin is loaded.
 *
 * PLUGIN_SET_TRANSLATABLE_INFO() takes two more parameters than PLUGIN_SET_INFO(),
 * for a total of six parameters.
 *
 *  - Localedir
 *  - Gettextpackage
 *  - Plugin name
 *  - Short description
 *  - Version
 *  - Author
 *
 * The @a Localdir and the @a Gettextpackage parameters are usually set inside
 * the build system.  If this has been done, the call for example HelloWorld
 * plugin could look like:
 *
 * @code
PLUGIN_SET_TRANSLATABLE_INFO(
        LOCALEDIR, GETTEXT_PACKAGE, _("Hello World"),
        _("Just another tool to say hello world"),
        "1.0", "John Doe <john.doe@example.org>");
 * @endcode
 *
 * When using this macro, you should use the gettext macro @a _() to mark
 * the strings like name and the short description as translatable as well. You
 * can see how this is done in the above example.
 *
 * As you can see the author's information is not marked as translatable in
 * this example.  The community has agreed that the best practice here is to
 * use, if possible, the latin version of the author's name followed by the
 * native spelling inside parenthesis, where applicable.
 *
 * @subsection plugin_i18n Using i18n/l10n inside Plugin
 *

 * You can (and should) also mark other strings beside the plugin's meta
 * information as translatable.  Strings used in menu entries, information
 * boxes or configuration dialogs should also be translatable as well.  Geany
 * offers a way to enable this in the plugin's code using the main_locale_init()
 * function provided by the plugin API. This function takes the same two
 * parameters discussed in the previous section; @a GETTEXT_PACKAGE and
 * @a LOCALEDIR.
 *
 * The main_locale_init() function is best called during initialization in the
 * plugin's plugin_init() function.  Adding this to the HelloWorld example could
 * look like:
 * @code
void plugin_init(GeanyData *data)
{
        main_locale_init(LOCALEDIR, GETTEXT_PACKAGE);
        main_menu_item = gtk_menu_item_new_with_mnemonic("Hello World");
        gtk_widget_show(main_menu_item);
        gtk_container_add(GTK_CONTAINER(geany->main_widgets->tools_menu),
                main_menu_item);
        g_signal_connect(main_menu_item, "activate",
                G_CALLBACK(item_activate_cb), NULL);
}
 * @endcode
 *
 * @note If you've previously called the PLUGIN_SET_TRANSLATABLE_INFO() you do not
 * need to call main_locale_init() yourself, as this has been already been
 * done for you.
 **/