Emmanuele Bassi

    	  ebassi@gmail.com

# Migrating from EggRecent to GtkRecentChooser

Since version 2.10, GTK+ provides a way of handling the recently used documents. It is similar to the code that has lived inside the libegg library and has been incorporated by many applications. The GTK+ version aims to completely replace that code, and offers many distinctive features that improve the registration and visualization of the recently used documents, such as:

- Better performances while reading and writing the list of recently used files

- More meta-data available for each recent document, like the applications that have registered a document inside the list, the last time and the number of times the same application did register a document inside the list, an optional user readable name and description of the document

- Improved the ability to sort and filter the documents, also using custom sorting and filtering functions

- New widgets for displaying the list, and better integration with current #GtkFileChooser and #GtkUIManager widgets

## Managing the Recently Used Documents

#GtkRecentManager is used to manage the Recently Used Documents. To create a new #GtkRecentManager, you simply call gtk_recent_manager_new(). Like the EggRecentModel inside EggRecent, the #GtkRecentManager loads the list of the recent documents and notifies you of changes inside the list.

Usually, instead of creating a new #GtkRecentManager each time you need it, you'll want to use the gtk_recent_manager_get_default() function.

To add a document to the list, you can use gtk_recent_manager_add_item(), like:

            GtkRecentManager *manager;

    	manager = gtk_recent_manager_new ();

    	if (!gtk_recent_manager_add_item (manager, document_uri))
    	  {
    	    /* warn about the error */
    	  }

    	g_object_unref (manager);

The gtk_recent_manager_add_item() function will try and guess some of the meta-data associated to a URI. If you know some of meta-data about the document yourself, set the desired fields of a #GtkRecentData structure and pass it to the gtk_recent_manager_add_full() function instead:

            GtkRecentManager *manager;
            GtkRecentData *recent_data;

    	manager = gtk_recent_manager_new ();

    	recent_data = g_new0 (GtkRecentData, 1);
    	/* the user visible name of the document (maybe its title); should
    	 * be preferred when displaying the item into the list
    	 */
            recent_data->display_name = document_name;

    	/* the MIME type is mandatory */
    	recent_data->mime_type = document_mime_type;

    	/* the name of the application that is registering the document
    	 * (also mandatory); usually, the same name you used with
    	 * the g_set_application_name () function.
    	 */
    	recent_data-&app_name = APP_NAME;

    	/* the command to open a file; the %u string will be automagically
    	 * expanded to the document's URI when getting the application's
    	 * command line from the GtkRecentInfo object with
    	 * gtk_recent_info_get_application_info ()
    	 */
    	recent_data-&app_exec = g_strjoin (" ", g_get_prgname (), "--open-file", "%u", NULL);

    	if (!gtk_recent_manager_add_full (manager, document_uri, recent_data))
    	  {
    	    /* warn about the error */
    	  }

    	g_free (recent_data->app_exec);
    	g_free (recent_data);
    	g_object_unref (manager);

Getting the list of items is also similar to EggRecentModel; the GtkRecentInfo data is allocated at look up time in order not to waste memory keeping it around, so you must remember to free the data inside the list and then the list itself when you are done using it:

            GtkRecentManager *manager;
            GList *recent_items, *l;

    	manager = gtk_recent_manager_get_default();

    	recent_items = gtk_recent_manager_get_items (manager);
    	for (l = recent_items; l != NULL; l = l->next)
    	  {
    	    GtkRecentInfo *recent_info = l->data;

    	    do_something_with_the_item (recent_info);
    	  }

    	/* free everything and the list */
    	g_list_foreach (recent_items, (GFunc) gtk_recent_info_unref, NULL);
    	g_list_free (recent_items);

You can also look up a single item:

            GtkRecentInfo *recent_info;
    	GError *error = NULL;

    	recent_info = gtk_recent_manager_lookup_item (manager, document_uri, &error);
    	if (error)
    	  {
    	    display_error (error);

    	    g_error_free (error);
    	  }
    	else
    	  {
    	    do_something_with_the_item (recent_info);

    	    gtk_recent_info_unref (recent_info);
    	  }

The #GtkRecentInfo is a reference counted boxed type, and it holds all the meta-data of a recently used document, like its display name, its description, the list of each application that has registered the document or the list of groups to which the document belong.

## Displaying the Recently Used Documents

Displaying the Recently Used Documents list is handled by any widget implementing the #GtkRecentChooser interface. These widgets also handle the sorting and filtering of the list; they will create their own #GtkRecentManager objects by default:

            GtkWidget *chooser;
    	gint response;

    	/* create a new dialog with the recently used documents list shown
    	 * using a GtkTreeView widget
    	 */
    	chooser = gtk_recent_chooser_dialog_new ("Recent Documents",
    	                                         parent_window,
    						 GTK_STOCK_CLOSE, GTK_RESPONSE_CANCEL,
    						 GTK_STOCK_OPEN, GTK_RESPONSE_OK,
    						 NULL);
            /* set the sorting order to "most recently used first" */
    	gtk_recent_chooser_set_sort_type (GTK_RECENT_CHOOSER (chooser), GTK_RECENT_SORT_MRU);
    	response = gtk_dialog_run (GTK_DIALOG (chooser));
    	if (response == GTK_RESPONSE_OK)
    	  {
    	    GtkRecentInfo *info;

                info = gtk_recent_chooser_get_current_item (GTK_RECENT_CHOOSER (chooser));
    	    do_something_with_the_item (info);

    	    gtk_recent_info_unref (info);
    	  }

    	gtk_widget_destroy (chooser);

## Advanced usage

The #GtkRecentChooser widgets might display items sorted and filtered, either with already supplied or custom sorting and filtering functions. The biggest difference from the EggRecentView widgets in EggRecent is that the #GtkRecentChooser widgets will use their own copy of the list and will apply the sorting and filtering functions only on the copy; this allows the creation of many viewers with a single controller, like using many #GtkTreeView with a single #GtkTreeModel instance.

Available sorting methods are:

            /* no sorting */
    	gtk_recent_chooser_set_sort_type (GTK_RECENT_CHOOSER (chooser), GTK_RECENT_SORT_NONE);

            /* most recently used first */
    	gtk_recent_chooser_set_sort_type (GTK_RECENT_CHOOSER (chooser), GTK_RECENT_SORT_MRU);

    	/* most recently used last */
    	gtk_recent_chooser_set_sort_type (GTK_RECENT_CHOOSER (chooser), GTK_RECENT_SORT_LRU);

You can create your own sorting function, and the use the GTK_RECENT_SORT_CUSTOM method:

    	/* custom sorting function, based on the registration count
    	 * (most used first)
    	 */
    	static void
    	sort_by_usage_count (GtkRecentInfo *a,
                                 GtkRecentInfo *b,
                                 gpointer       data)
            {
    	  gint count_a, count_b;

    	  count_a = count_b = 0;

    	  if (gtk_recent_info_has_application (a, APP_NAME))
    	    gtk_recent_info_get_application_info (a, APP_NAME, NULL, &count_a, NULL);

    	  if (gtk_recent_info_has_application (b, APP_NAME))
    	    gtk_recent_info_get_application_info (b, APP_NAME, NULL, &count_b, NULL);

    	  return count_a < count_b;
    	}

    	...

    	  /* set custom sorting and set the custom sorting function */
    	  gtk_recent_chooser_set_sort_type (GTK_RECENT_CHOOSER (chooser),
    	                                    GTK_RECENT_SORT_CUSTOM);
    	  gtk_recent_chooser_set_sort_func (GTK_RECENT_CHOOSER,
    	                                    sort_by_usage_count,
    			  		    NULL, /* sort function data */
    					    NULL  /* destroy notify for the data */);

Filtering is done using the #GtkRecentFilter object, similar to the #GtkFileFilter object used by the #GtkFileChooser widgets. The #GtkRecentFilter object has a set of pre-defined options based on the meta-data exposed by the #GtkRecentInfo object. It also allows custom filtering function:

            GtkRecentFilter *filter;

    	filter = gtk_recent_filter_new ();

    	/* set the user visible name of the filter */
    	gtk_recent_filter_set_name (filter, "Since Last Month");

    	/* set the maximum age of a recently used document */
    	gtk_recent_filter_set_age (filter, 31);

    	/* the chooser takes the ownership of the object */
    	gtk_recent_chooser_add_filter (GTK_RECENT_CHOOSER (chooser), filter);

    	/* set the currently used filter */
    	gtk_recent_chooser_set_filter (GTK_RECENT_CHOOSER (chooser), filter);

    	filter = gtk_recent_filter_new ();
    	gtk_recent_filter_set_name (filter, "Every text file");
    	gtk_recent_filter_set_mime_type (filter, "text/plain");

    	gtk_recent_chooser_add_filter (GTK_RECENT_CHOOSER (chooser), filter);

The #GtkRecentChooserWidget and #GtkRecentChooserDialog widgets allow multiple filters and the selection of an appropriate one; the #GtkRecentChooserMenu widget allows just a single filter object.