listview: Introduce GtkListItemFactory

Thisis the abstraction I intend to use for creating widgets and binding
them to the item out of the listview.

For now this is a very dumb wrapper around the functions that exist in
the API.

But it leaves the freedom to turn this into public API, make an
interface out of it and most of all write different implementations, in
particular one that uses GtkBuilder.

docs/reference/gtk/gtk4-sections.txt

@@ -393,6 +393,20 @@ gtk_single_selection_get_type
 </SECTION>
 
 <SECTION>
+<FILE>gtklistitemfactory</FILE>
+<TITLE>GtkListItemFactory</TITLE>
+GtkListItemFactory
+<SUBSECTION Standard>
+GTK_LIST_ITEM_FACTORY
+GTK_LIST_ITEM_FACTORY_CLASS
+GTK_LIST_ITEM_FACTORY_GET_CLASS
+GTK_IS_LIST_ITEM_FACTORY
+GTK_IS_LIST_ITEM_FACTORY_CLASS
+GTK_TYPE_LIST_ITEM_FACTORY
+<SUBSECTION Private>
+gtk_list_item_factory_get_type
+</SECTION>
+
 <FILE>gtklistview</FILE>
 <TITLE>GtkListView</TITLE>
 GtkListView

docs/reference/gtk/gtk4.types.in

@@ -119,6 +119,7 @@ gtk_label_get_type
 gtk_layout_child_get_type
 gtk_layout_manager_get_type
 gtk_link_button_get_type
+gtk_list_item_factory_get_type
 gtk_list_store_get_type
 gtk_list_box_get_type
 gtk_list_box_row_get_type

docs/reference/gtk/meson.build

@@ -132,6 +132,7 @@ private_headers = [
   'gtkimmoduleprivate.h',
   'gtkkineticscrollingprivate.h',
   'gtklabelprivate.h',
+  'gtklistitemfactoryprivate.h',
   'gtklockbuttonprivate.h',
   'gtkmagnifierprivate.h',
   'gtkmediafileprivate.h',

gtk/gtklistitemfactory.c

@@ -0,0 +1,153 @@
+/*
+ * Copyright © 2018 Benjamin Otte
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Benjamin Otte <otte@gnome.org>
+ */
+
+#include "config.h"
+
+#include "gtklistitemfactoryprivate.h"
+
+/**
+ * SECTION:gtklistitemfactory
+ * @Title: GtkListItemFactory
+ * @Short_description: Mapping list items to widgets
+ *
+ * #GtkListItemFactory is one of the core concepts of handling list widgets.
+ * It is the object tasked with creating widgets for items taken from a
+ * #GListModel when the views need them and updating them as the items
+ * displayed by the view change.
+ *
+ * A view is usually only able to display anything after both a factory
+ * and a model have been set on the view. So it is important that you do
+ * not skip this step when setting up your first view.
+ *
+ * Because views do not display the whole list at once but only a few
+ * items, they only need to maintain a few widgets at a time. They will
+ * instruct the #GtkListItemFactory to create these widgets and bind them
+ * to the items that are currently displayed.  
+ * As the list model changes or the user scrolls to the list, the items will
+ * change and the view will instruct the factory to bind the widgets to those
+ * new items.
+ *
+ * The actual widgets used for displaying those widgets is provided by you.
+ *
+ * When the factory needs widgets created, it will create a #GtkListItem and
+ * hand it to your code to set up a widget for. This list item will provide
+ * various properties with information about what item to display and provide
+ * you with some opportunities to configure its behavior. See the #GtkListItem
+ * documentation for further details.
+ *
+ * Various implementations of #GtkListItemFactory exist to allow you different
+ * ways to provide those widgets. The most common implementations are
+ * #GtkBuilderListItemFactory which takes a #GtkBuilder .ui file and then creates
+ * and manages widgets everything automatically from the information in that file
+ * and #GtkSignalListItemFactory which allows you to connect to signals with your
+ * own code and retain full control over how the widgets are setup and managed.
+ *
+ * A #GtkListItemFactory is supposed to be final - that means its behavior should
+ * not change and the first widget created from it should behave the same way as
+ * the last widget created from it.  
+ * If you intend to do changes to the behavior, it is recommended that you create
+ * a new #GtkListItemFactory which will allow the views to recreate its widgets.
+ *
+ * Once you have chosen your factory and created it, you need to set it on the
+ * view widget you want to use it with, such as via gtk_list_view_set_factory().
+ * Reusing factories across different views is allowed, but very uncommon.
+ */
+
+struct _GtkListItemFactory
+{
+  GObject parent_instance;
+
+  GtkListCreateWidgetFunc create_func;
+  GtkListBindWidgetFunc bind_func;
+  gpointer user_data;
+  GDestroyNotify user_destroy;
+};
+
+struct _GtkListItemFactoryClass
+{
+  GObjectClass parent_class;
+};
+
+G_DEFINE_TYPE (GtkListItemFactory, gtk_list_item_factory, G_TYPE_OBJECT)
+
+static void
+gtk_list_item_factory_finalize (GObject *object)
+{
+  GtkListItemFactory *self = GTK_LIST_ITEM_FACTORY (object);
+
+  if (self->user_destroy)
+    self->user_destroy (self->user_data);
+
+  G_OBJECT_CLASS (gtk_list_item_factory_parent_class)->finalize (object);
+}
+
+static void
+gtk_list_item_factory_class_init (GtkListItemFactoryClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->finalize = gtk_list_item_factory_finalize;
+}
+
+static void
+gtk_list_item_factory_init (GtkListItemFactory *self)
+{
+}
+
+GtkListItemFactory *
+gtk_list_item_factory_new (GtkListCreateWidgetFunc create_func,
+                           GtkListBindWidgetFunc   bind_func,
+                           gpointer                user_data,
+                           GDestroyNotify          user_destroy)
+{
+  GtkListItemFactory *self;
+
+  g_return_val_if_fail (create_func, NULL);
+  g_return_val_if_fail (bind_func, NULL);
+  g_return_val_if_fail (user_data != NULL || user_destroy == NULL, NULL);
+
+  self = g_object_new (GTK_TYPE_LIST_ITEM_FACTORY, NULL);
+
+  self->create_func = create_func;
+  self->bind_func = bind_func;
+  self->user_data = user_data;
+  self->user_destroy = user_destroy;
+
+  return self;
+}
+
+GtkWidget *
+gtk_list_item_factory_create (GtkListItemFactory *self)
+{
+  g_return_val_if_fail (GTK_IS_LIST_ITEM_FACTORY (self), NULL);
+
+  return self->create_func (self->user_data);
+}
+
+void
+gtk_list_item_factory_bind (GtkListItemFactory *self,
+                            GtkWidget          *widget,
+                            gpointer            item)
+{
+  g_return_if_fail (GTK_IS_LIST_ITEM_FACTORY (self));
+  g_return_if_fail (GTK_IS_WIDGET (widget));
+
+  self->bind_func (widget, item, self->user_data);
+}
+

gtk/gtklistitemfactoryprivate.h

@@ -0,0 +1,54 @@
+/*
+ * Copyright © 2018 Benjamin Otte
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Benjamin Otte <otte@gnome.org>
+ */
+
+
+#ifndef __GTK_LIST_ITEM_FACTORY_H__
+#define __GTK_LIST_ITEM_FACTORY_H__
+
+#include <gtk/gtklistview.h>
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_LIST_ITEM_FACTORY         (gtk_list_item_factory_get_type ())
+#define GTK_LIST_ITEM_FACTORY(o)           (G_TYPE_CHECK_INSTANCE_CAST ((o), GTK_TYPE_LIST_ITEM_FACTORY, GtkListItemFactory))
+#define GTK_LIST_ITEM_FACTORY_CLASS(k)     (G_TYPE_CHECK_CLASS_CAST ((k), GTK_TYPE_LIST_ITEM_FACTORY, GtkListItemFactoryClass))
+#define GTK_IS_LIST_ITEM_FACTORY(o)        (G_TYPE_CHECK_INSTANCE_TYPE ((o), GTK_TYPE_LIST_ITEM_FACTORY))
+#define GTK_IS_LIST_ITEM_FACTORY_CLASS(k)  (G_TYPE_CHECK_CLASS_TYPE ((k), GTK_TYPE_LIST_ITEM_FACTORY))
+#define GTK_LIST_ITEM_FACTORY_GET_CLASS(o) (G_TYPE_INSTANCE_GET_CLASS ((o), GTK_TYPE_LIST_ITEM_FACTORY, GtkListItemFactoryClass))
+
+typedef struct _GtkListItemFactory GtkListItemFactory;
+typedef struct _GtkListItemFactoryClass GtkListItemFactoryClass;
+
+GType                   gtk_list_item_factory_get_type          (void) G_GNUC_CONST;
+
+GtkListItemFactory *    gtk_list_item_factory_new               (GtkListCreateWidgetFunc create_func,
+                                                                 GtkListBindWidgetFunc   bind_func,
+                                                                 gpointer                user_data,
+                                                                 GDestroyNotify          user_destroy);
+
+GtkWidget *             gtk_list_item_factory_create            (GtkListItemFactory     *self);
+
+void                    gtk_list_item_factory_bind              (GtkListItemFactory     *self,
+                                                                 GtkWidget              *widget,
+                                                                 gpointer                item);
+
+
+G_END_DECLS
+
+#endif /* __GTK_LIST_ITEM_FACTORY_H__ */

gtk/gtklistview.c

@@ -22,7 +22,7 @@
 #include "gtklistview.h"
 
 #include "gtkintl.h"
-#include "gtkprivate.h"
+#include "gtklistitemfactoryprivate.h"
 
 /**
  * SECTION:gtklistview
@@ -38,6 +38,7 @@ struct _GtkListView
   GtkWidget parent_instance;
 
   GListModel *model;
+  GtkListItemFactory *item_factory;
 };
 
 enum
@@ -116,6 +117,8 @@ gtk_list_view_dispose (GObject *object)
 
   gtk_list_view_clear_model (self);
 
+  g_clear_object (&self->item_factory);
+
   G_OBJECT_CLASS (gtk_list_view_parent_class)->dispose (object);
 }
 
@@ -258,3 +261,20 @@ gtk_list_view_set_model (GtkListView *self,
   g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_MODEL]);
 }
 
+void
+gtk_list_view_set_functions (GtkListView            *self,
+                             GtkListCreateWidgetFunc create_func,
+                             GtkListBindWidgetFunc   bind_func,
+                             gpointer                user_data,
+                             GDestroyNotify          user_destroy)
+{
+  g_return_if_fail (GTK_IS_LIST_VIEW (self));
+  g_return_if_fail (create_func);
+  g_return_if_fail (bind_func);
+  g_return_if_fail (user_data != NULL || user_destroy == NULL);
+
+  g_clear_object (&self->item_factory);
+
+  self->item_factory = gtk_list_item_factory_new (create_func, bind_func, user_data, user_destroy);
+}
+

gtk/gtklistview.h

@@ -28,6 +28,36 @@
 
 G_BEGIN_DECLS
 
+/**
+ * GtkListCreateWidgetFunc:
+ * @user_data: (closure): user data
+ *
+ * Called whenever a new widget needs to be created for managing a row in
+ * the list.
+ *
+ * The widget will later be bound to an item via the #GtkListBindWidgetFunc.
+ *
+ * Returns: (transfer full): a #GtkWidget
+ */
+typedef GtkWidget * (* GtkListCreateWidgetFunc) (gpointer user_data);
+
+/**
+ * GtkListBindWidgetFunc:
+ * @widget: The #GtkWidget to bind
+ * @item: (type GObject) (allow-none): item to bind or %NULL to unbind
+ *     the widget.
+ * @user_data: (closure): user data
+ *
+ * Binds a widget previously created via a #GtkListCreateWidgetFunc to
+ * an @item.
+ *
+ * Rebinding a @widget to different @items is supported as well as
+ * unbinding it by setting @item to %NULL.
+ */
+typedef void (* GtkListBindWidgetFunc) (GtkWidget *widget,
+                                        gpointer   item,
+                                        gpointer   user_data);
+
 #define GTK_TYPE_LIST_VIEW         (gtk_list_view_get_type ())
 
 GDK_AVAILABLE_IN_ALL
@@ -41,7 +71,12 @@ GListModel *    gtk_list_view_get_model                         (GtkListView
 GDK_AVAILABLE_IN_ALL
 void            gtk_list_view_set_model                         (GtkListView            *self,
                                                                  GListModel             *model);
-
+GDK_AVAILABLE_IN_ALL
+void            gtk_list_view_set_functions                     (GtkListView            *self,
+                                                                 GtkListCreateWidgetFunc create_func,
+                                                                 GtkListBindWidgetFunc   bind_func,
+                                                                 gpointer                user_data,
+                                                                 GDestroyNotify          user_destroy);
 
 G_END_DECLS
 

gtk/meson.build

@@ -271,6 +271,7 @@ gtk_public_sources = files([
   'gtklevelbar.c',
   'gtklinkbutton.c',
   'gtklistbox.c',
+  'gtklistitemfactory.c',
   'gtklistlistmodel.c',
   'gtkliststore.c',
   'gtklistview.c',