Renderers are extensions, therefore, the first step is to obtain a reference to them using the framework registry, like this:

MafwProxyRegistry *registry = MAFW_REGISTRY(mafw_registry_get_instance());
if (registry) {
        GList *renderers = mafw_registry_get_renderers(MAFW_REGISTRY(registry));
}

The code above allows the application developer to obtain a list of available renderers. The developer can use this list to show the available renderers to the users, allowing them to select the renderer they are interested in.

Once a reference to the appropriate renderer has been obtained the application developer can start using it. Here is a simple example:

static void
_generic_error_cb(MafwExtension *extension, guint domain, guint code, gchar *message, 
                  gpointer user_data)
{
        /* Error management code here */
}

static void
error_cb(MafwRenderer* renderer, gpointer user_data, const GError* error)
{
        if (error != NULL) {
                /* Error management code here */
        } else {
                /* Operation was successful */
        }
}

static void
play_button_clicked_cb(GtkButton *button, gpointer user_data)
{
        MafwRenderer *renderer = (MafwRenderer *) user_data;
        mafw_renderer_play(renderer, error_cb, NULL);
}

static void
pause_button_clicked_cb(GtkButton *button, gpointer user_data)
{
        MafwRenderer *renderer = (MafwRenderer *) user_data;
        mafw_renderer_pause(renderer, error_cb, NULL);
}

static void
resume_button_clicked_cb(GtkButton *button, gpointer user_data)
{
        MafwRenderer *renderer = (MafwRenderer *) user_data;
        mafw_renderer_resume(renderer, error_cb, NULL);
}

static void
stop_button_clicked_cb(GtkButton *button, gpointer user_data)
{
        MafwRenderer *renderer = (MafwRenderer *) user_data;
        mafw_renderer_stop(renderer, error_cb, NULL);
}

static void
state_changed_cb(MafwRenderer *renderer, MafwPlayState state, gpointer user_data)
{
        switch (state) {
                case Playing:
                        /* Enable Pause button */
                        break;
                case Paused:
                        /* Enable Resume button */
                        break;
                case Stopped:
                        /* Disable Pause/Resume button */
                        break;
                default:
                        break;
        }
}

static void
media_changed_cb(MafwRenderer *renderer, gint index, gchar *object_id, 
                 gpointer user_data)
{
        if (index >= 0) {
                /* Update UI: select item at position 'index' */
        } else {
               /* Playlist playback interrupted, maybe inform the user
                  about this and then wait until it is resumed, then we 
                  will get a new media-changed signal */
        }
}

static void 
assign_playlist_cb(MafwRenderer *renderer, gpointer user_data, const GError *error)
{
        if (error != NULL) {
                /* error management code here */
        } else {
               /* Start playback right away! */
                mafw_renderer_play(renderer, error_cb, NULL);
        }
}

static void 
renderer_example(void) 
{
        MafwRenderer *renderer = NULL;

        MafwProxyRegistry *registry = 
                MAFW_REGISTRY(mafw_registry_get_instance());

        if (registry) {
                GList *renderers = 
                        mafw_registry_get_renderers(MAFW_REGISTRY(registry));
                if (renderers) {
                        /* Just take the first one available */
                        renderer = (MafwRenderer *) renderers->data;
                        g_object_ref(renderer);
                }
        }

        if (renderer) {
                g_signal_connect(MAFW_EXTENSION(renderer), "error",
                                 G_CALLBACK(_generic_error_cb), NULL);
                g_signal_connect(renderer, "state-changed",
                                 G_CALLBACK(state_changed_cb), NULL);
                g_signal_connect(renderer, "media-changed",
                                 G_CALLBACK(media_changed_cb), NULL);
     
                mafw_renderer_assign_playlist(renderer, playlist, 
                                          assign_playlist_cb, NULL);
        }
}

The code above assumes an application with four playback buttons (Play, Pause, Resume and Stop), being *_button_clicked_cb the handlers for the clicked events of these buttons.

The program starts by selecting a suitable renderer if any, then it assigns a playlist to the renderer, and, if the playlist could be assigned, it starts playing it right away. As the reader can see, mafw_renderer_play plays the item currently selected in the renderer.

For further details on the renderer API, please check the Mafw API reference.