
    <para>
	This section explains the steps required to write a plugin for Parole using
	the C language interface.
    </para>

    <para>
	A simple example can be found in the parole plugins dir shipped with the source code, the sample
	plugin.
    </para>
    <para>
	As a basics, the plugin needs to implement <link linkend="ParoleProviderPlugin"><type>ParoleProviderPlugin</type></link>
	interface, That is, the player use this interface to get if the plugin is configurable, to ask it to show
	its properties dialog when needed, to set the <link linkend="ParoleProviderPlayer"><type>ParoleProviderPlayer</type></link>
	interface used by plugins to access the the Parole player backend.
    </para>


  <sect1>
    <title>Plugin structure.</title>
    sample-plugin.c
    <programlisting>
#include "src/misc/parole.h"

#include "src/plugins/sample/sample-provider.h"

G_MODULE_EXPORT GType   parole_plugin_initialize(ParoleProviderPlugin *plugin);

G_MODULE_EXPORT void    parole_plugin_shutdown(void);

G_MODULE_EXPORT GType
parole_plugin_initialize(ParoleProviderPlugin *plugin) {
    xfce_textdomain(GETTEXT_PACKAGE, PACKAGE_LOCALE_DIR, "UTF-8");
    sample_provider_register_type(plugin);
    return SAMPLE_TYPE_PROVIDER;
}

G_MODULE_EXPORT void
parole_plugin_shutdown(void) {
}
    </programlisting>

    sample-provider.h
    <programlisting>
#ifndef SRC_PLUGINS_SAMPLE_SAMPLE_PROVIDER_H_
#define SRC_PLUGINS_SAMPLE_SAMPLE_PROVIDER_H_

#include "src/misc/parole.h"

G_BEGIN_DECLS

typedef struct _SampleProviderClass SampleProviderClass;
typedef struct _SampleProvider      SampleProvider;

#define SAMPLE_TYPE_PROVIDER             (sample_provider_get_type ())
#define SAMPLE_PROVIDER(obj)             (G_TYPE_CHECK_INSTANCE_CAST ((obj), SAMPLE_TYPE_PROVIDER, SampleProvider))
#define SAMPLE_PROVIDER_CLASS(klass)     (G_TYPE_CHECK_CLASS_CAST ((klass), SAMPLE_TYPE_PROVIDER, SampleProviderClass))
#define SAMPLE_IS_PROVIDER(obj)          (G_TYPE_CHECK_INSTANCE_TYPE ((obj), SAMPLE_TYPE_PROVIDER))
#define SAMPLE_IS_PROVIDER_CLASS(klass)  (G_TYPE_CHECK_CLASS_TYPE ((klass), SAMPLE_TYPE_PROVIDER))
#define SAMPLE_PROVIDER_GET_CLASS(obj)   (G_TYPE_INSTANCE_GET_CLASS ((obj), SAMPLE_TYPE_PROVIDER, SampleProviderClass))

GType sample_provider_get_type           (void) G_GNUC_CONST G_GNUC_INTERNAL;

void  sample_provider_register_type      (ParoleProviderPlugin *plugin);

G_END_DECLS

#endif /* SRC_PLUGINS_SAMPLE_SAMPLE_PROVIDER_H_ */
    </programlisting>

    sample-provider.c
    <programlisting>
#include "src/plugins/sample/sample-provider.h"

static void   sample_provider_iface_init(ParoleProviderPluginIface *iface);
static void   sample_provider_finalize(GObject                     *object);


struct _SampleProviderClass {
    GObjectClass parent_class;
};

struct _SampleProvider {
    GObject                 parent;
    ParoleProviderPlayer   *player;
};

PAROLE_DEFINE_TYPE_WITH_CODE(SampleProvider,
                             sample_provider,
                             G_TYPE_OBJECT,
                             PAROLE_IMPLEMENT_INTERFACE(PAROLE_TYPE_PROVIDER_PLUGIN,
                             sample_provider_iface_init));

static gboolean sample_provider_is_configurable(ParoleProviderPlugin *plugin) {
    return FALSE;
}

static void
sample_provider_set_player(ParoleProviderPlugin *plugin, ParoleProviderPlayer *player) {
    SampleProvider *provider;
    provider = SAMPLE_PROVIDER(plugin);

    provider->player = player;
}

static void
sample_provider_iface_init(ParoleProviderPluginIface *iface) {
    iface->get_is_configurable = sample_provider_is_configurable;
    iface->set_player = sample_provider_set_player;
}

static void sample_provider_class_init(SampleProviderClass *klass) {
    GObjectClass *gobject_class = G_OBJECT_CLASS(klass);

    gobject_class->finalize = sample_provider_finalize;
}

static void sample_provider_init(SampleProvider *provider) {
    provider->player = NULL;
}

static void sample_provider_finalize(GObject *object) {
    G_OBJECT_CLASS(sample_provider_parent_class)->finalize(object);
}
    </programlisting>

  </sect1>
