[gtk/wip/otte/listview: 308/327] listview: Add GtkListItemManager

[Benjamin Otte <otte src gnome org>]

commit 2d472da14b09568058d37786ad3854362a3617b8
Author: Benjamin Otte <otte redhat com>
Date:   Thu Sep 20 05:18:34 2018 +0200

    listview: Add GtkListItemManager
    
    It's all stubs for now, but here's the basic ideas about what
    this object is supposed to do:
    
    (1) It's supposed to be handling all the child GtkWidgets that are
        used by the listview, so that the listview can concern
        itself with how many items it needs and where to put them.
    (2) It's meant to do the caching of widgets that are not (currently)
        used.
    (3) It's meant to track items that remain in the model across
        items-changed emissions and just change position.
    (2) It's code that can be shared between listview and potential
        other widgets like a GridView.
    
    It's also free to assume that the number of items it's supposed to
    manage doesn't grow too much, so it's free to use O(N) algorithms.

 gtk/gtklistitemmanager.c        | 181 ++++++++++++++++++++++++++++++++++++++++
 gtk/gtklistitemmanagerprivate.h |  62 ++++++++++++++
 gtk/gtklistview.c               |  25 ++++--
 gtk/meson.build                 |   1 +
 4 files changed, 260 insertions(+), 9 deletions(-)
---
diff --git a/gtk/gtklistitemmanager.c b/gtk/gtklistitemmanager.c
new file mode 100644
index 0000000000..28630bda99
--- /dev/null
+++ b/gtk/gtklistitemmanager.c
@@ -0,0 +1,181 @@
+/*
+ * 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 "gtklistitemmanagerprivate.h"
+
+struct _GtkListItemManager
+{
+  GObject parent_instance;
+
+  GtkWidget *widget;
+  GListModel *model;
+  GtkListItemFactory *factory;
+};
+
+struct _GtkListItemManagerClass
+{
+  GObjectClass parent_class;
+};
+
+G_DEFINE_TYPE (GtkListItemManager, gtk_list_item_manager, G_TYPE_OBJECT)
+
+static void
+gtk_list_item_manager_dispose (GObject *object)
+{
+  GtkListItemManager *self = GTK_LIST_ITEM_MANAGER (object);
+
+  g_clear_object (&self->model);
+  g_clear_object (&self->factory);
+
+  G_OBJECT_CLASS (gtk_list_item_manager_parent_class)->dispose (object);
+}
+
+static void
+gtk_list_item_manager_class_init (GtkListItemManagerClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->dispose = gtk_list_item_manager_dispose;
+}
+
+static void
+gtk_list_item_manager_init (GtkListItemManager *self)
+{
+}
+
+GtkListItemManager *
+gtk_list_item_manager_new (GtkWidget *widget)
+{
+  GtkListItemManager *self;
+
+  g_return_val_if_fail (GTK_IS_WIDGET (widget), NULL);
+
+  self = g_object_new (GTK_TYPE_LIST_ITEM_MANAGER, NULL);
+
+  self->widget = widget;
+
+  return self;
+}
+
+void
+gtk_list_item_manager_set_factory (GtkListItemManager *self,
+                                   GtkListItemFactory *factory)
+{
+  g_return_if_fail (GTK_IS_LIST_ITEM_MANAGER (self));
+  g_return_if_fail (GTK_IS_LIST_ITEM_FACTORY (factory));
+
+  if (self->factory == factory)
+    return;
+
+  g_clear_object (&self->factory);
+
+  self->factory = g_object_ref (factory);
+}
+
+GtkListItemFactory *
+gtk_list_item_manager_get_factory (GtkListItemManager *self)
+{
+  g_return_val_if_fail (GTK_IS_LIST_ITEM_MANAGER (self), NULL);
+
+  return self->factory;
+}
+
+void
+gtk_list_item_manager_set_model (GtkListItemManager *self,
+                                 GListModel         *model)
+{
+  g_return_if_fail (GTK_IS_LIST_ITEM_MANAGER (self));
+  g_return_if_fail (model == NULL || G_IS_LIST_MODEL (model));
+
+  if (self->model == model)
+    return;
+
+  g_clear_object (&self->model);
+
+  if (model)
+    self->model = g_object_ref (model);
+}
+
+GListModel *
+gtk_list_item_manager_get_model (GtkListItemManager *self)
+{
+  g_return_val_if_fail (GTK_IS_LIST_ITEM_MANAGER (self), NULL);
+
+  return self->model;
+}
+
+/*
+ * gtk_list_item_manager_model_changed:
+ * @self: a #GtkListItemManager
+ * @position: the position at which the model changed
+ * @removed: the number of items removed
+ * @added: the number of items added
+ *
+ * This function must be called by the owning @widget at the
+ * appropriate time.  
+ * The manager does not connect to GListModel::items-changed itself
+ * but relies on its widget calling this function.
+ *
+ * This function should be called after @widget has released all
+ * #GListItems it intends to delete in response to the @removed rows
+ * but before it starts creating new ones for the @added rows.
+ **/
+void
+gtk_list_item_manager_model_changed (GtkListItemManager *self,
+                                     guint               position,
+                                     guint               removed,
+                                     guint               added)
+{
+  g_return_if_fail (GTK_IS_LIST_ITEM_MANAGER (self));
+  g_return_if_fail (self->model != NULL);
+}
+
+/*
+ * gtk_list_item_manager_create_list_item:
+ * @self: a #GtkListItemManager
+ * @position: the row in the model to create a list item for
+ * @next_sibling: the widget this widget should be inserted before or %NULL
+ *     if none
+ *
+ * Creates a new list item widget to use for @position. No widget may
+ * yet exist that is used for @position.
+ *
+ * Returns: a properly setup widget to use in @position
+ **/
+GtkWidget *
+gtk_list_item_manager_create_list_item (GtkListItemManager *self,
+                                        guint               position,
+                                        GtkWidget          *next_sibling)
+{
+  GtkWidget *result;
+  gpointer item;
+
+  g_return_val_if_fail (GTK_IS_LIST_ITEM_MANAGER (self), NULL);
+  g_return_val_if_fail (next_sibling == NULL || GTK_IS_WIDGET (next_sibling), NULL);
+
+  result = gtk_list_item_factory_create (self->factory);
+  item = g_list_model_get_item (self->model, position);
+  gtk_list_item_factory_bind (self->factory, result, item);
+  g_object_unref (item);
+  gtk_widget_insert_before (result, self->widget, next_sibling);
+
+  return result;
+}
diff --git a/gtk/gtklistitemmanagerprivate.h b/gtk/gtklistitemmanagerprivate.h
new file mode 100644
index 0000000000..34b57da97e
--- /dev/null
+++ b/gtk/gtklistitemmanagerprivate.h
@@ -0,0 +1,62 @@
+/*
+ * 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_MANAGER_H__
+#define __GTK_LIST_ITEM_MANAGER_H__
+
+#include "gtk/gtktypes.h"
+
+#include "gtk/gtklistitemfactoryprivate.h"
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_LIST_ITEM_MANAGER         (gtk_list_item_manager_get_type ())
+#define GTK_LIST_ITEM_MANAGER(o)           (G_TYPE_CHECK_INSTANCE_CAST ((o), GTK_TYPE_LIST_ITEM_MANAGER, 
GtkListItemManager))
+#define GTK_LIST_ITEM_MANAGER_CLASS(k)     (G_TYPE_CHECK_CLASS_CAST ((k), GTK_TYPE_LIST_ITEM_MANAGER, 
GtkListItemManagerClass))
+#define GTK_IS_LIST_ITEM_MANAGER(o)        (G_TYPE_CHECK_INSTANCE_TYPE ((o), GTK_TYPE_LIST_ITEM_MANAGER))
+#define GTK_IS_LIST_ITEM_MANAGER_CLASS(k)  (G_TYPE_CHECK_CLASS_TYPE ((k), GTK_TYPE_LIST_ITEM_MANAGER))
+#define GTK_LIST_ITEM_MANAGER_GET_CLASS(o) (G_TYPE_INSTANCE_GET_CLASS ((o), GTK_TYPE_LIST_ITEM_MANAGER, 
GtkListItemManagerClass))
+
+typedef struct _GtkListItemManager GtkListItemManager;
+typedef struct _GtkListItemManagerClass GtkListItemManagerClass;
+
+GType                   gtk_list_item_manager_get_type          (void) G_GNUC_CONST;
+
+GtkListItemManager *    gtk_list_item_manager_new               (GtkWidget              *widget);
+
+void                    gtk_list_item_manager_set_factory       (GtkListItemManager     *self,
+                                                                 GtkListItemFactory     *factory);
+GtkListItemFactory *    gtk_list_item_manager_get_factory       (GtkListItemManager     *self);
+void                    gtk_list_item_manager_set_model         (GtkListItemManager     *self,
+                                                                 GListModel             *model);
+GListModel *            gtk_list_item_manager_get_model         (GtkListItemManager     *self);
+
+
+void                    gtk_list_item_manager_model_changed     (GtkListItemManager     *self,
+                                                                 guint                   position,
+                                                                 guint                   removed,
+                                                                 guint                   added);
+GtkWidget *             gtk_list_item_manager_create_list_item  (GtkListItemManager     *self,
+                                                                 guint                   position,
+                                                                 GtkWidget              *next_sibling);
+
+G_END_DECLS
+
+#endif /* __GTK_LIST_ITEM_MANAGER_H__ */
diff --git a/gtk/gtklistview.c b/gtk/gtklistview.c
index acda283f44..23fd8c482b 100644
--- a/gtk/gtklistview.c
+++ b/gtk/gtklistview.c
@@ -25,6 +25,7 @@
 #include "gtkintl.h"
 #include "gtkcssrbtreeprivate.h"
 #include "gtklistitemfactoryprivate.h"
+#include "gtklistitemmanagerprivate.h"
 #include "gtkscrollable.h"
 #include "gtksnapshot.h"
 #include "gtkwidgetprivate.h"
@@ -46,7 +47,7 @@ struct _GtkListView
   GtkWidget parent_instance;
 
   GListModel *model;
-  GtkListItemFactory *item_factory;
+  GtkListItemManager *item_manager;
   GtkAdjustment *adjustment[2];
   GtkScrollablePolicy scroll_policy[2];
 
@@ -518,14 +519,12 @@ gtk_list_view_add_rows (GtkListView *self,
   for (i = 0; i < n_rows; i++)
     {
       ListRow *new_row;
-      gpointer item;
         
       new_row = gtk_css_rb_tree_insert_before (self->rows, row);
       new_row->n_rows = 1;
-      new_row->widget = gtk_list_item_factory_create (self->item_factory);
-      gtk_widget_insert_before (new_row->widget, GTK_WIDGET (self), row ? row->widget : NULL);
-      item = g_list_model_get_item (self->model, position + i);
-      gtk_list_item_factory_bind (self->item_factory, new_row->widget, item);
+      new_row->widget = gtk_list_item_manager_create_list_item (self->item_manager,
+                                                                position + i,
+                                                                row ? row->widget : NULL);
     }
 
   gtk_widget_queue_resize (GTK_WIDGET (self));
@@ -539,6 +538,7 @@ gtk_list_view_model_items_changed_cb (GListModel  *model,
                                       GtkListView *self)
 {
   gtk_list_view_remove_rows (self, position, removed);
+  gtk_list_item_manager_model_changed (self->item_manager, position, removed, added);
   gtk_list_view_add_rows (self, position, added);
 }
 
@@ -608,7 +608,7 @@ gtk_list_view_dispose (GObject *object)
   gtk_list_view_clear_adjustment (self, GTK_ORIENTATION_HORIZONTAL);
   gtk_list_view_clear_adjustment (self, GTK_ORIENTATION_VERTICAL);
 
-  g_clear_object (&self->item_factory);
+  g_clear_object (&self->item_manager);
 
   G_OBJECT_CLASS (gtk_list_view_parent_class)->dispose (object);
 }
@@ -619,6 +619,7 @@ gtk_list_view_finalize (GObject *object)
   GtkListView *self = GTK_LIST_VIEW (object);
 
   gtk_css_rb_tree_unref (self->rows);
+  g_clear_object (&self->item_manager);
 
   G_OBJECT_CLASS (gtk_list_view_parent_class)->finalize (object);
 }
@@ -787,6 +788,8 @@ gtk_list_view_class_init (GtkListViewClass *klass)
 static void
 gtk_list_view_init (GtkListView *self)
 {
+  self->item_manager = gtk_list_item_manager_new (GTK_WIDGET (self));
+
   self->rows = gtk_css_rb_tree_new (ListRow,
                                     ListRowAugment,
                                     list_row_augment,
@@ -847,6 +850,8 @@ gtk_list_view_set_model (GtkListView *self,
 
   gtk_list_view_clear_model (self);
 
+  gtk_list_item_manager_set_model (self->item_manager, model);
+
   if (model)
     {
       self->model = g_object_ref (model);
@@ -869,6 +874,7 @@ gtk_list_view_set_functions (GtkListView            *self,
                              gpointer                user_data,
                              GDestroyNotify          user_destroy)
 {
+  GtkListItemFactory *factory;
   guint n_items;
 
   g_return_if_fail (GTK_IS_LIST_VIEW (self));
@@ -879,8 +885,9 @@ gtk_list_view_set_functions (GtkListView            *self,
   n_items = self->model ? g_list_model_get_n_items (self->model) : 0;
   gtk_list_view_remove_rows (self, 0, n_items);
 
-  g_clear_object (&self->item_factory);
-  self->item_factory = gtk_list_item_factory_new (create_func, bind_func, user_data, user_destroy);
+  factory = gtk_list_item_factory_new (create_func, bind_func, user_data, user_destroy);
+  gtk_list_item_manager_set_factory (self->item_manager, factory);
+  g_object_unref (factory);
 
   gtk_list_view_add_rows (self, 0, n_items);
 }
diff --git a/gtk/meson.build b/gtk/meson.build
index 36da504ce9..1ccd425dee 100644
--- a/gtk/meson.build
+++ b/gtk/meson.build
@@ -267,6 +267,7 @@ gtk_public_sources = files([
   'gtklinkbutton.c',
   'gtklistbox.c',
   'gtklistitemfactory.c',
+  'gtklistitemmanager.c',
   'gtklistlistmodel.c',
   'gtkliststore.c',
   'gtklistview.c',