listview: GtkListHeader and gtk_list_view_set_header_factory()

Adds infrastructure for handling factories for list headers.

For now, listitemmanager doesn't instantiate them, so they aren't used.

gtk/gtk.h

@@ -174,6 +174,7 @@
 #include <gtk/gtklistbase.h>
 #include <gtk/gtklinkbutton.h>
 #include <gtk/gtklistbox.h>
+#include <gtk/gtklistheader.h>
 #include <gtk/gtklistitem.h>
 #include <gtk/gtklistitemfactory.h>
 #include <gtk/deprecated/gtkliststore.h>

gtk/gtklistheader.c

@@ -0,0 +1,381 @@
+/*
+ * Copyright © 2023 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 "gtklistheaderprivate.h"
+
+/**
+ * GtkListHeader:
+ *
+ * `GtkListHeader` is used by list widgets to represent the headers they
+ * display.
+ *
+ * The `GtkListHeader`s are managed just like [class@gtk.ListItem]s via
+ * their factory, but provide a different set of properties suitable for
+ * managing the header instead of individual items.
+ *
+ * Since: 4.12
+ */
+
+enum
+{
+  PROP_0,
+  PROP_CHILD,
+  PROP_END,
+  PROP_ITEM,
+  PROP_N_ITEMS,
+  PROP_START,
+
+  N_PROPS
+};
+
+G_DEFINE_TYPE (GtkListHeader, gtk_list_header, G_TYPE_OBJECT)
+
+static GParamSpec *properties[N_PROPS] = { NULL, };
+
+static void
+gtk_list_header_dispose (GObject *object)
+{
+  GtkListHeader *self = GTK_LIST_HEADER (object);
+
+  g_assert (self->owner == NULL); /* would hold a reference */
+  g_clear_object (&self->child);
+
+  G_OBJECT_CLASS (gtk_list_header_parent_class)->dispose (object);
+}
+
+static void
+gtk_list_header_get_property (GObject    *object,
+                              guint       property_id,
+                              GValue     *value,
+                              GParamSpec *pspec)
+{
+  GtkListHeader *self = GTK_LIST_HEADER (object);
+
+  switch (property_id)
+    {
+    case PROP_CHILD:
+      g_value_set_object (value, self->child);
+      break;
+
+    case PROP_END:
+      if (self->owner)
+        g_value_set_uint (value, gtk_list_header_base_get_end (GTK_LIST_HEADER_BASE (self->owner)));
+      else
+        g_value_set_uint (value, GTK_INVALID_LIST_POSITION);
+      break;
+
+    case PROP_ITEM:
+      if (self->owner)
+        g_value_set_object (value, gtk_list_header_base_get_item (GTK_LIST_HEADER_BASE (self->owner)));
+      break;
+
+    case PROP_N_ITEMS:
+      g_value_set_uint (value, gtk_list_header_get_n_items (self));
+      break;
+
+    case PROP_START:
+      if (self->owner)
+        g_value_set_uint (value, gtk_list_header_base_get_start (GTK_LIST_HEADER_BASE (self->owner)));
+      else
+        g_value_set_uint (value, GTK_INVALID_LIST_POSITION);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gtk_list_header_set_property (GObject      *object,
+                              guint         property_id,
+                              const GValue *value,
+                              GParamSpec   *pspec)
+{
+  GtkListHeader *self = GTK_LIST_HEADER (object);
+
+  switch (property_id)
+    {
+    case PROP_CHILD:
+      gtk_list_header_set_child (self, g_value_get_object (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gtk_list_header_class_init (GtkListHeaderClass *klass)
+{
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+
+  gobject_class->dispose = gtk_list_header_dispose;
+  gobject_class->get_property = gtk_list_header_get_property;
+  gobject_class->set_property = gtk_list_header_set_property;
+
+  /**
+   * GtkListHeader:child: (attributes org.gtk.Property.get=gtk_list_header_get_child org.gtk.Property.set=gtk_list_header_set_child)
+   *
+   * Widget used for display.
+   *
+   * Since: 4.12
+   */
+  properties[PROP_CHILD] =
+    g_param_spec_object ("child", NULL, NULL,
+                         GTK_TYPE_WIDGET,
+                         G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
+
+  /**
+   * GtkListHeader:end: (attributes org.gtk.Property.get=gtk_list_header_get_end)
+   *
+   * The first position no longer part of this section.
+   *
+   * Since: 4.12
+   */
+  properties[PROP_END] =
+    g_param_spec_uint ("end", NULL, NULL,
+                       0, G_MAXUINT, GTK_INVALID_LIST_POSITION,
+                       G_PARAM_READABLE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
+
+  /**
+   * GtkListHeader:item: (attributes org.gtk.Property.get=gtk_list_header_get_item)
+   *
+   * The item at the start of the section.
+   *
+   * Since: 4.12
+   */
+  properties[PROP_ITEM] =
+    g_param_spec_object ("item", NULL, NULL,
+                         G_TYPE_OBJECT,
+                         G_PARAM_READABLE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
+
+  /**
+   * GtkListHeader:n-items: (attributes org.gtk.Property.get=gtk_list_header_get_n_items)
+   *
+   * Number of items in this section.
+   *
+   * Since: 4.12
+   */
+  properties[PROP_N_ITEMS] =
+    g_param_spec_uint ("n-items", NULL, NULL,
+                       0, G_MAXUINT, 0,
+                       G_PARAM_READABLE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
+
+  /**
+   * GtkListHeader:start: (attributes org.gtk.Property.get=gtk_list_header_get_start)
+   *
+   * First position of items in this section.
+   *
+   * Since: 4.12
+   */
+  properties[PROP_START] =
+    g_param_spec_uint ("start", NULL, NULL,
+                       0, G_MAXUINT, GTK_INVALID_LIST_POSITION,
+                       G_PARAM_READABLE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
+
+  g_object_class_install_properties (gobject_class, N_PROPS, properties);
+}
+
+static void
+gtk_list_header_init (GtkListHeader *self)
+{
+}
+
+GtkListHeader *
+gtk_list_header_new (void)
+{
+  return g_object_new (GTK_TYPE_LIST_HEADER, NULL);
+}
+
+void
+gtk_list_header_do_notify (GtkListHeader *list_header,
+                           gboolean notify_item,
+                           gboolean notify_start,
+                           gboolean notify_end,
+                           gboolean notify_n_items)
+{
+  GObject *object = G_OBJECT (list_header);
+
+  if (notify_item)
+    g_object_notify_by_pspec (object, properties[PROP_ITEM]);
+  if (notify_start)
+    g_object_notify_by_pspec (object, properties[PROP_START]);
+  if (notify_end)
+    g_object_notify_by_pspec (object, properties[PROP_END]);
+  if (notify_n_items)
+    g_object_notify_by_pspec (object, properties[PROP_N_ITEMS]);
+}
+
+/**
+ * gtk_list_header_get_item: (attributes org.gtk.Method.get_property=item)
+ * @self: a `GtkListHeader`
+ *
+ * Gets the model item at the start of the section.
+ * This is the item that occupies the list model at position
+ * [property@Gtk.ListHeader:start].
+ *
+ * If @self is unbound, this function returns %NULL.
+ *
+ * Returns: (nullable) (transfer none) (type GObject): The item displayed
+ *
+ * Since: 4.12
+ **/
+gpointer
+gtk_list_header_get_item (GtkListHeader *self)
+{
+  g_return_val_if_fail (GTK_IS_LIST_HEADER (self), NULL);
+
+  if (self->owner)
+    return gtk_list_header_base_get_item (GTK_LIST_HEADER_BASE (self->owner));
+  else
+    return NULL;
+}
+
+/**
+ * gtk_list_header_get_child: (attributes org.gtk.Method.get_property=child)
+ * @self: a `GtkListHeader`
+ *
+ * Gets the child previously set via gtk_list_header_set_child() or
+ * %NULL if none was set.
+ *
+ * Returns: (transfer none) (nullable): The child
+ *
+ * Since: 4.12
+ */
+GtkWidget *
+gtk_list_header_get_child (GtkListHeader *self)
+{
+  g_return_val_if_fail (GTK_IS_LIST_HEADER (self), NULL);
+
+  return self->child;
+}
+
+/**
+ * gtk_list_header_set_child: (attributes org.gtk.Method.set_property=child)
+ * @self: a `GtkListHeader`
+ * @child: (nullable): The list item's child or %NULL to unset
+ *
+ * Sets the child to be used for this listitem.
+ *
+ * This function is typically called by applications when
+ * setting up a header so that the widget can be reused when
+ * binding it multiple times.
+ *
+ * Since: 4.12
+ */
+void
+gtk_list_header_set_child (GtkListHeader *self,
+                           GtkWidget   *child)
+{
+  g_return_if_fail (GTK_IS_LIST_HEADER (self));
+  g_return_if_fail (child == NULL || gtk_widget_get_parent (child) == NULL);
+
+  if (self->child == child)
+    return;
+
+  g_clear_object (&self->child);
+
+  if (child)
+    {
+      g_object_ref_sink (child);
+      self->child = child;
+    }
+
+  if (self->owner)
+    gtk_list_header_widget_set_child (self->owner, child);
+
+  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_CHILD]);
+}
+
+/**
+ * gtk_list_header_get_start: (attributes org.gtk.Method.get_property=start)
+ * @self: a `GtkListHeader`
+ *
+ * Gets the start position in the model of the section that @self is
+ * currently the header for.
+ *
+ * If @self is unbound, %GTK_INVALID_LIST_POSITION is returned.
+ *
+ * Returns: The start position of the section
+ *
+ * Since: 4.12
+ */
+guint
+gtk_list_header_get_start (GtkListHeader *self)
+{
+  g_return_val_if_fail (GTK_IS_LIST_HEADER (self), GTK_INVALID_LIST_POSITION);
+
+  if (self->owner)
+    return gtk_list_header_base_get_start (GTK_LIST_HEADER_BASE (self->owner));
+  else
+    return GTK_INVALID_LIST_POSITION;
+}
+
+/**
+ * gtk_list_header_get_end: (attributes org.gtk.Method.get_property=end)
+ * @self: a `GtkListHeader`
+ *
+ * Gets the end position in the model of the section that @self is
+ * currently the header for.
+ *
+ * If @self is unbound, %GTK_INVALID_LIST_POSITION is returned.
+ *
+ * Returns: The end position of the section
+ *
+ * Since: 4.12
+ */
+guint
+gtk_list_header_get_end (GtkListHeader *self)
+{
+  g_return_val_if_fail (GTK_IS_LIST_HEADER (self), GTK_INVALID_LIST_POSITION);
+
+  if (self->owner)
+    return gtk_list_header_base_get_end (GTK_LIST_HEADER_BASE (self->owner));
+  else
+    return GTK_INVALID_LIST_POSITION;
+}
+
+/**
+ * gtk_list_header_get_n_items: (attributes org.gtk.Method.get_property=n-items)
+ * @self: a `GtkListHeader`
+ *
+ * Gets the the number of items in the section.
+ *
+ * If @self is unbound, 0 is returned.
+ *
+ * Returns: The number of items in the section
+ *
+ * Since: 4.12
+ */
+guint
+gtk_list_header_get_n_items (GtkListHeader *self)
+{
+  g_return_val_if_fail (GTK_IS_LIST_HEADER (self), GTK_INVALID_LIST_POSITION);
+
+  if (self->owner)
+    return gtk_list_header_base_get_end (GTK_LIST_HEADER_BASE (self->owner)) -
+           gtk_list_header_base_get_start (GTK_LIST_HEADER_BASE (self->owner));
+  else
+    return 0;
+}
+

gtk/gtklistheader.h

@@ -0,0 +1,50 @@
+/*
+ * Copyright © 2023 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>
+ */
+
+#pragma once
+
+#if !defined (__GTK_H_INSIDE__) && !defined (GTK_COMPILATION)
+#error "Only <gtk/gtk.h> can be included directly."
+#endif
+
+#include <gtk/gtktypes.h>
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_LIST_HEADER (gtk_list_header_get_type ())
+GDK_AVAILABLE_IN_4_12
+GDK_DECLARE_INTERNAL_TYPE (GtkListHeader, gtk_list_header, GTK, LIST_HEADER, GObject)
+
+GDK_AVAILABLE_IN_4_12
+gpointer        gtk_list_header_get_item                        (GtkListHeader          *self);
+GDK_AVAILABLE_IN_4_12
+guint           gtk_list_header_get_start                       (GtkListHeader          *self) G_GNUC_PURE;
+GDK_AVAILABLE_IN_4_12
+guint           gtk_list_header_get_end                         (GtkListHeader          *self) G_GNUC_PURE;
+GDK_AVAILABLE_IN_4_12
+guint           gtk_list_header_get_n_items                     (GtkListHeader          *self) G_GNUC_PURE;
+
+GDK_AVAILABLE_IN_4_12
+void            gtk_list_header_set_child                       (GtkListHeader          *self,
+                                                                 GtkWidget              *child);
+GDK_AVAILABLE_IN_4_12
+GtkWidget *     gtk_list_header_get_child                       (GtkListHeader          *self);
+
+G_END_DECLS
+

gtk/gtklistheaderbase.c

@@ -76,6 +76,13 @@ gtk_list_header_base_update (GtkListHeaderBase *self,
                              guint              start,
                              guint              end)
 {
+  GtkListHeaderBasePrivate *priv = gtk_list_header_base_get_instance_private (self);
+
+  if (priv->item == item &&
+      priv->start == start && 
+      priv->end == end)
+    return;
+
   GTK_LIST_HEADER_BASE_GET_CLASS (self)->update (self, item, start, end);
 }
 

gtk/gtklistheaderprivate.h

@@ -0,0 +1,52 @@
+/*
+ * Copyright © 2023 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>
+ */
+
+#pragma once
+
+#include "gtklistheader.h"
+
+#include "gtklistheaderwidgetprivate.h"
+
+G_BEGIN_DECLS
+
+struct _GtkListHeader
+{
+  GObject parent_instance;
+
+  GtkListHeaderWidget *owner; /* has a reference */
+
+  GtkWidget *child;
+};
+
+struct _GtkListHeaderClass
+{
+  GObjectClass parent_class;
+};
+
+GtkListHeader * gtk_list_header_new                             (void);
+
+void            gtk_list_header_do_notify                       (GtkListHeader          *list_header,
+                                                                 gboolean                notify_item,
+                                                                 gboolean                notify_start,
+                                                                 gboolean                notify_end,
+                                                                 gboolean                notify_n_items);
+
+
+G_END_DECLS
+

gtk/gtklistheaderwidget.c

@@ -0,0 +1,295 @@
+/*
+ * Copyright © 2023 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 "gtklistheaderwidgetprivate.h"
+
+#include "gtkbinlayout.h"
+#include "gtklistheaderprivate.h"
+#include "gtklistitemfactoryprivate.h"
+#include "gtklistbaseprivate.h"
+#include "gtkwidget.h"
+
+typedef struct _GtkListHeaderWidgetPrivate GtkListHeaderWidgetPrivate;
+struct _GtkListHeaderWidgetPrivate
+{
+  GtkListItemFactory *factory;
+
+  GtkListHeader *header;
+};
+
+enum {
+  PROP_0,
+  PROP_FACTORY,
+
+  N_PROPS
+};
+
+G_DEFINE_TYPE_WITH_PRIVATE (GtkListHeaderWidget, gtk_list_header_widget, GTK_TYPE_LIST_HEADER_BASE)
+
+static GParamSpec *properties[N_PROPS] = { NULL, };
+
+static void
+gtk_list_header_widget_setup_func (gpointer object,
+                                   gpointer data)
+{
+  GtkListHeaderWidget *self = GTK_LIST_HEADER_WIDGET (data);
+  GtkListHeaderWidgetPrivate *priv = gtk_list_header_widget_get_instance_private (self);
+  GtkListHeader *header = object;
+
+  priv->header = header;
+  header->owner = self;
+
+  gtk_list_header_widget_set_child (self, header->child);
+
+  gtk_list_header_do_notify (header,
+                             gtk_list_header_base_get_item (GTK_LIST_HEADER_BASE (self)) != NULL,
+                             gtk_list_header_base_get_start (GTK_LIST_HEADER_BASE (self)) != GTK_INVALID_LIST_POSITION,
+                             gtk_list_header_base_get_end (GTK_LIST_HEADER_BASE (self)) != GTK_INVALID_LIST_POSITION,
+                             gtk_list_header_base_get_start (GTK_LIST_HEADER_BASE (self)) != gtk_list_header_base_get_end (GTK_LIST_HEADER_BASE (self)));
+}
+
+static void
+gtk_list_header_widget_setup_factory (GtkListHeaderWidget *self)
+{
+  GtkListHeaderWidgetPrivate *priv = gtk_list_header_widget_get_instance_private (self);
+  GtkListHeader *header;
+
+  header = gtk_list_header_new ();
+
+  gtk_list_item_factory_setup (priv->factory,
+                               G_OBJECT (header),
+                               gtk_list_header_base_get_item (GTK_LIST_HEADER_BASE (self)) != NULL,
+                               gtk_list_header_widget_setup_func,
+                               self);
+
+  g_assert (priv->header == header);
+}
+
+static void
+gtk_list_header_widget_teardown_func (gpointer object,
+                                      gpointer data)
+{
+  GtkListHeaderWidget *self = GTK_LIST_HEADER_WIDGET (data);
+  GtkListHeaderWidgetPrivate *priv = gtk_list_header_widget_get_instance_private (self);
+  GtkListHeader *header = object;
+
+  header->owner = NULL;
+  priv->header = NULL;
+
+  gtk_list_header_widget_set_child (self, NULL);
+
+  gtk_list_header_do_notify (header,
+                             gtk_list_header_base_get_item (GTK_LIST_HEADER_BASE (self)) != NULL,
+                             gtk_list_header_base_get_start (GTK_LIST_HEADER_BASE (self)) != GTK_INVALID_LIST_POSITION,
+                             gtk_list_header_base_get_end (GTK_LIST_HEADER_BASE (self)) != GTK_INVALID_LIST_POSITION,
+                             gtk_list_header_base_get_start (GTK_LIST_HEADER_BASE (self)) != gtk_list_header_base_get_end (GTK_LIST_HEADER_BASE (self)));
+}
+
+static void
+gtk_list_header_widget_teardown_factory (GtkListHeaderWidget *self)
+{
+  GtkListHeaderWidgetPrivate *priv = gtk_list_header_widget_get_instance_private (self);
+  gpointer header = priv->header;
+
+  gtk_list_item_factory_teardown (priv->factory,
+                                  header,
+                                  gtk_list_header_base_get_item (GTK_LIST_HEADER_BASE (self)) != NULL,
+                                  gtk_list_header_widget_teardown_func,
+                                  self);
+
+  g_assert (priv->header == NULL);
+  g_object_unref (header);
+}
+
+typedef struct {
+  GtkListHeaderWidget *widget;
+  gpointer item;
+  guint start;
+  guint end;
+} GtkListHeaderWidgetUpdate;
+
+static void
+gtk_list_header_widget_update_func (gpointer object,
+                                    gpointer data)
+{
+  GtkListHeaderWidgetUpdate *update = data;
+  GtkListHeaderWidget *self = update->widget;
+  GtkListHeaderBase *base = GTK_LIST_HEADER_BASE (self);
+  /* Track notify manually instead of freeze/thaw_notify for performance reasons. */
+  gboolean notify_item, notify_start, notify_end, notify_n_items;
+
+  /* FIXME: It's kinda evil to notify external objects from here... */
+  notify_item = gtk_list_header_base_get_item (base) != update->item;
+  notify_start = gtk_list_header_base_get_start (base) != update->start;
+  notify_end = gtk_list_header_base_get_end (base) != update->end;
+  notify_n_items = gtk_list_header_base_get_end (base) - gtk_list_header_base_get_start (base) != update->end - update->start;
+
+  GTK_LIST_HEADER_BASE_CLASS (gtk_list_header_widget_parent_class)->update (base,
+                                                                            update->item,
+                                                                            update->start,
+                                                                            update->end);
+
+  if (object)
+    gtk_list_header_do_notify (object, notify_item, notify_start, notify_end, notify_n_items);
+}
+
+static void
+gtk_list_header_widget_update (GtkListHeaderBase *base,
+                               gpointer           item,
+                               guint              start,
+                               guint              end)
+{
+  GtkListHeaderWidget *self = GTK_LIST_HEADER_WIDGET (base);
+  GtkListHeaderWidgetPrivate *priv = gtk_list_header_widget_get_instance_private (self);
+  GtkListHeaderWidgetUpdate update = { self, item, start, end };
+
+  if (priv->header)
+    {
+      gtk_list_item_factory_update (priv->factory,
+                                    G_OBJECT (priv->header),
+                                    gtk_list_header_base_get_item (GTK_LIST_HEADER_BASE (self)) != NULL,
+                                    item != NULL,
+                                    gtk_list_header_widget_update_func,
+                                    &update);
+    }
+  else
+    {
+      gtk_list_header_widget_update_func (NULL, &update);
+    }
+}
+
+static void
+gtk_list_header_widget_set_property (GObject      *object,
+                                     guint         property_id,
+                                     const GValue *value,
+                                     GParamSpec   *pspec)
+{
+  GtkListHeaderWidget *self = GTK_LIST_HEADER_WIDGET (object);
+
+  switch (property_id)
+    {
+    case PROP_FACTORY:
+      gtk_list_header_widget_set_factory (self, g_value_get_object (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gtk_list_header_widget_clear_factory (GtkListHeaderWidget *self)
+{
+  GtkListHeaderWidgetPrivate *priv = gtk_list_header_widget_get_instance_private (self);
+
+  if (priv->factory == NULL)
+    return;
+
+  if (priv->header)
+    gtk_list_header_widget_teardown_factory (self);
+
+  g_clear_object (&priv->factory);
+}
+
+static void
+gtk_list_header_widget_dispose (GObject *object)
+{
+  GtkListHeaderWidget *self = GTK_LIST_HEADER_WIDGET (object);
+
+  gtk_list_header_widget_clear_factory (self);
+
+  G_OBJECT_CLASS (gtk_list_header_widget_parent_class)->dispose (object);
+}
+
+static void
+gtk_list_header_widget_class_init (GtkListHeaderWidgetClass *klass)
+{
+  GtkListHeaderBaseClass *base_class = GTK_LIST_HEADER_BASE_CLASS (klass);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+
+  base_class->update = gtk_list_header_widget_update;
+
+  gobject_class->set_property = gtk_list_header_widget_set_property;
+  gobject_class->dispose = gtk_list_header_widget_dispose;
+
+  properties[PROP_FACTORY] =
+    g_param_spec_object ("factory", NULL, NULL,
+                         GTK_TYPE_LIST_ITEM_FACTORY,
+                         G_PARAM_WRITABLE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
+
+  g_object_class_install_properties (gobject_class, N_PROPS, properties);
+
+  gtk_widget_class_set_css_name (widget_class, I_("header"));
+  gtk_widget_class_set_accessible_role (widget_class, GTK_ACCESSIBLE_ROLE_ROW_HEADER);
+  gtk_widget_class_set_layout_manager_type (widget_class, GTK_TYPE_BIN_LAYOUT);
+}
+
+static void
+gtk_list_header_widget_init (GtkListHeaderWidget *self)
+{
+}
+
+void
+gtk_list_header_widget_set_factory (GtkListHeaderWidget *self,
+                                    GtkListItemFactory  *factory)
+{
+  GtkListHeaderWidgetPrivate *priv = gtk_list_header_widget_get_instance_private (self);
+
+  if (priv->factory == factory)
+    return;
+
+  gtk_list_header_widget_clear_factory (self);
+
+  if (factory)
+    {
+      priv->factory = g_object_ref (factory);
+
+      gtk_list_header_widget_setup_factory (self);
+    }
+
+  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_FACTORY]);
+}
+
+GtkWidget *
+gtk_list_header_widget_new (GtkListItemFactory *factory)
+{
+  return g_object_new (GTK_TYPE_LIST_HEADER_WIDGET,
+                       "factory", factory,
+                       NULL);
+}
+
+void
+gtk_list_header_widget_set_child (GtkListHeaderWidget *self,
+                                  GtkWidget           *child)
+{
+  GtkWidget *cur_child = gtk_widget_get_first_child (GTK_WIDGET (self));
+
+  if (cur_child == child)
+    return;
+
+  g_clear_pointer (&cur_child, gtk_widget_unparent);
+
+  if (child)
+    gtk_widget_set_parent (child, GTK_WIDGET (self));
+}
+

gtk/gtklistheaderwidgetprivate.h

@@ -0,0 +1,61 @@
+/*
+ * Copyright © 2023 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>
+ */
+
+#pragma once
+
+#include "gtklistheaderbaseprivate.h"
+
+#include "gtklistitemfactory.h"
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_LIST_HEADER_WIDGET         (gtk_list_header_widget_get_type ())
+#define GTK_LIST_HEADER_WIDGET(o)           (G_TYPE_CHECK_INSTANCE_CAST ((o), GTK_TYPE_LIST_HEADER_WIDGET, GtkListHeaderWidget))
+#define GTK_LIST_HEADER_WIDGET_CLASS(k)     (G_TYPE_CHECK_CLASS_CAST ((k), GTK_TYPE_LIST_HEADER_WIDGET, GtkListHeaderWidgetClass))
+#define GTK_IS_LIST_HEADER_WIDGET(o)        (G_TYPE_CHECK_INSTANCE_TYPE ((o), GTK_TYPE_LIST_HEADER_WIDGET))
+#define GTK_IS_LIST_HEADER_WIDGET_CLASS(k)  (G_TYPE_CHECK_CLASS_TYPE ((k), GTK_TYPE_LIST_HEADER_WIDGET))
+#define GTK_LIST_HEADER_WIDGET_GET_CLASS(o) (G_TYPE_INSTANCE_GET_CLASS ((o), GTK_TYPE_LIST_HEADER_WIDGET, GtkListHeaderWidgetClass))
+
+typedef struct _GtkListHeaderWidget GtkListHeaderWidget;
+typedef struct _GtkListHeaderWidgetClass GtkListHeaderWidgetClass;
+
+struct _GtkListHeaderWidget
+{
+  GtkListHeaderBase parent_instance;
+};
+
+struct _GtkListHeaderWidgetClass
+{
+  GtkListHeaderBaseClass parent_class;
+};
+
+GType                   gtk_list_header_widget_get_type         (void) G_GNUC_CONST;
+
+GtkWidget *             gtk_list_header_widget_new              (GtkListItemFactory     *factory);
+
+void                    gtk_list_header_widget_set_factory      (GtkListHeaderWidget    *self,
+                                                                 GtkListItemFactory     *factory);
+GtkListItemFactory *    gtk_list_header_widget_get_factory      (GtkListHeaderWidget    *self);
+
+void                    gtk_list_header_widget_set_child        (GtkListHeaderWidget    *self,
+                                                                 GtkWidget              *child);
+
+
+G_END_DECLS
+

gtk/gtklistview.c

@@ -23,6 +23,7 @@
 
 #include "gtkbitset.h"
 #include "gtklistbaseprivate.h"
+#include "gtklistheaderwidgetprivate.h"
 #include "gtklistitemmanagerprivate.h"
 #include "gtklistitemwidgetprivate.h"
 #include "gtkmultiselection.h"
@@ -145,6 +146,7 @@ enum
   PROP_0,
   PROP_ENABLE_RUBBERBAND,
   PROP_FACTORY,
+  PROP_HEADER_FACTORY,
   PROP_MODEL,
   PROP_SHOW_SEPARATORS,
   PROP_SINGLE_CLICK_ACTIVATE,
@@ -163,29 +165,6 @@ G_DEFINE_TYPE (GtkListView, gtk_list_view, GTK_TYPE_LIST_BASE)
 static GParamSpec *properties[N_PROPS] = { NULL, };
 static guint signals[LAST_SIGNAL] = { 0 };
 
-static void G_GNUC_UNUSED
-dump (GtkListView *self)
-{
-  GtkListTile *tile;
-  guint n_widgets, n_list_rows;
-
-  n_widgets = 0;
-  n_list_rows = 0;
-  //g_print ("ANCHOR: %u - %u\n", self->anchor_start, self->anchor_end);
-  for (tile = gtk_list_item_manager_get_first (self->item_manager);
-       tile;
-       tile = gtk_rb_tree_node_get_next (tile))
-    {
-      if (tile->widget)
-        n_widgets++;
-      n_list_rows++;
-      g_print ("  %4u%s %d,%d,%d,%d\n", tile->n_items, tile->widget ? " (widget)" : "",
-               tile->area.x, tile->area.y, tile->area.width, tile->area.height);
-    }
-
-  g_print ("  => %u widgets in %u list rows\n", n_widgets, n_list_rows);
-}
-
 static GtkListTile *
 gtk_list_view_split (GtkListBase *base,
                      GtkListTile *tile,
@@ -215,6 +194,13 @@ gtk_list_view_split (GtkListBase *base,
   return new_tile;
 }
 
+static void
+gtk_list_view_prepare_section (GtkListBase *base,
+                               GtkListTile *tile,
+                               guint        position)
+{
+}
+
 /* We define the listview as **inert** when the factory isn't used. */
 static gboolean
 gtk_list_view_is_inert (GtkListView *self)
@@ -228,7 +214,8 @@ gtk_list_view_is_inert (GtkListView *self)
 
 static void
 gtk_list_view_update_factories_with (GtkListView        *self,
-                                     GtkListItemFactory *factory)
+                                     GtkListItemFactory *factory,
+                                     GtkListItemFactory *header_factory)
 {
   GtkListTile *tile;
 
@@ -236,8 +223,27 @@ gtk_list_view_update_factories_with (GtkListView        *self,
        tile != NULL;
        tile = gtk_rb_tree_node_get_next (tile))
     {
+      switch (tile->type)
+        {
+        case GTK_LIST_TILE_ITEM:
           if (tile->widget)
             gtk_list_factory_widget_set_factory (GTK_LIST_FACTORY_WIDGET (tile->widget), factory);
+          break;
+        case GTK_LIST_TILE_HEADER:
+          if (tile->widget)
+            gtk_list_header_widget_set_factory (GTK_LIST_HEADER_WIDGET (tile->widget), header_factory);
+          break;
+        case GTK_LIST_TILE_UNMATCHED_HEADER:
+        case GTK_LIST_TILE_FOOTER:
+        case GTK_LIST_TILE_UNMATCHED_FOOTER:
+        case GTK_LIST_TILE_FILLER:
+        case GTK_LIST_TILE_REMOVED:
+          g_assert (tile->widget == NULL);
+          break;
+        default:
+          g_assert_not_reached();
+          break;
+        }
     }
 }
 
@@ -245,13 +251,14 @@ static void
 gtk_list_view_update_factories (GtkListView *self)
 {
   gtk_list_view_update_factories_with (self,
-                                       gtk_list_view_is_inert (self) ? NULL : self->factory);
+                                       gtk_list_view_is_inert (self) ? NULL : self->factory,
+                                       gtk_list_view_is_inert (self) ? NULL : self->header_factory);
 }
 
 static void
 gtk_list_view_clear_factories (GtkListView *self)
 {
-  gtk_list_view_update_factories_with (self, NULL);
+  gtk_list_view_update_factories_with (self, NULL, NULL);
 }
 
 static GtkListItemBase *
@@ -275,6 +282,20 @@ gtk_list_view_create_list_widget (GtkListBase *base)
   return GTK_LIST_ITEM_BASE (result);
 }
 
+static GtkListHeaderBase *
+gtk_list_view_create_header_widget (GtkListBase *base)
+{
+  GtkListView *self = GTK_LIST_VIEW (base);
+  GtkListItemFactory *factory;
+
+  if (gtk_list_view_is_inert (self))
+    factory = NULL;
+  else
+    factory = self->header_factory;
+
+  return GTK_LIST_HEADER_BASE (gtk_list_header_widget_new (factory));
+}
+
 static gboolean
 gtk_list_view_get_allocation (GtkListBase  *base,
                               guint         pos,
@@ -527,8 +548,11 @@ gtk_list_view_measure_list (GtkWidget      *widget,
           gtk_widget_measure (tile->widget,
                               orientation, for_size,
                               &child_min, &child_nat, NULL, NULL);
+          if (tile->type == GTK_LIST_TILE_ITEM)
+            {
               g_array_append_val (min_heights, child_min);
               g_array_append_val (nat_heights, child_nat);
+            }
           min += child_min;
           nat += child_nat;
         }
@@ -622,6 +646,7 @@ gtk_list_view_size_allocate (GtkWidget *widget,
       else
         row_height = nat;
       gtk_list_tile_set_area_size (self->item_manager, tile, list_width, row_height);
+      if (tile->type == GTK_LIST_TILE_ITEM)
         g_array_append_val (heights, row_height);
     }
 
@@ -723,6 +748,10 @@ gtk_list_view_get_property (GObject    *object,
       g_value_set_object (value, self->factory);
       break;
 
+    case PROP_HEADER_FACTORY:
+      g_value_set_object (value, self->header_factory);
+      break;
+
     case PROP_MODEL:
       g_value_set_object (value, gtk_list_base_get_model (GTK_LIST_BASE (self)));
       break;
@@ -763,6 +792,10 @@ gtk_list_view_set_property (GObject      *object,
       gtk_list_view_set_factory (self, g_value_get_object (value));
       break;
 
+    case PROP_HEADER_FACTORY:
+      gtk_list_view_set_header_factory (self, g_value_get_object (value));
+      break;
+
     case PROP_MODEL:
       gtk_list_view_set_model (self, g_value_get_object (value));
       break;
@@ -812,6 +845,8 @@ gtk_list_view_class_init (GtkListViewClass *klass)
 
   list_base_class->split = gtk_list_view_split;
   list_base_class->create_list_widget = gtk_list_view_create_list_widget;
+  list_base_class->prepare_section = gtk_list_view_prepare_section;
+  list_base_class->create_header_widget = gtk_list_view_create_header_widget;
   list_base_class->get_allocation = gtk_list_view_get_allocation;
   list_base_class->get_items_in_rect = gtk_list_view_get_items_in_rect;
   list_base_class->get_position_from_allocation = gtk_list_view_get_position_from_allocation;
@@ -849,6 +884,18 @@ gtk_list_view_class_init (GtkListViewClass *klass)
                          GTK_TYPE_LIST_ITEM_FACTORY,
                          G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
 
+  /**
+   * GtkListView:header-factory: (attributes org.gtk.Property.get=gtk_list_view_get_header_factory org.gtk.Property.set=gtk_list_view_set_header_factory)
+   *
+   * Factory for creating header widgets.
+   *
+   * Since: 4.12
+   */
+  properties[PROP_HEADER_FACTORY] =
+    g_param_spec_object ("header-factory", NULL, NULL,
+                         GTK_TYPE_LIST_ITEM_FACTORY,
+                         G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
+
   /**
    * GtkListView:model: (attributes org.gtk.Property.get=gtk_list_view_get_model org.gtk.Property.set=gtk_list_view_set_model)
    *
@@ -1070,6 +1117,68 @@ gtk_list_view_set_factory (GtkListView        *self,
   g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_FACTORY]);
 }
 
+/**
+ * gtk_list_view_get_header_factory: (attributes org.gtk.Method.get_property=header-factory)
+ * @self: a `GtkListView`
+ *
+ * Gets the factory that's currently used to populate section headers.
+ *
+ * Returns: (nullable) (transfer none): The factory in use
+ *
+ * Since: 4.12
+ */
+GtkListItemFactory *
+gtk_list_view_get_header_factory (GtkListView *self)
+{
+  g_return_val_if_fail (GTK_IS_LIST_VIEW (self), NULL);
+
+  return self->header_factory;
+}
+
+/**
+ * gtk_list_view_set_header_factory: (attributes org.gtk.Method.set_property=header-factory)
+ * @self: a `GtkListView`
+ * @factory: (nullable) (transfer none): the factory to use
+ *
+ * Sets the `GtkListItemFactory` to use for populating the
+ * [class@Gtk.ListHeader] objects used in section headers.
+ *
+ * If this factory is set to %NULL, the list will not show section headers.
+ *
+ * Since: 4.12
+ */
+void
+gtk_list_view_set_header_factory (GtkListView        *self,
+                                  GtkListItemFactory *factory)
+{
+  gboolean had_sections;
+
+  g_return_if_fail (GTK_IS_LIST_VIEW (self));
+  g_return_if_fail (factory == NULL || GTK_IS_LIST_ITEM_FACTORY (factory));
+
+  had_sections = gtk_list_item_manager_get_has_sections (self->item_manager);
+
+  if (!g_set_object (&self->header_factory, factory))
+    return;
+
+  gtk_list_item_manager_set_has_sections (self->item_manager, factory != NULL);
+
+  if (had_sections && gtk_list_item_manager_get_has_sections (self->item_manager))
+    {
+      GtkListTile *tile;
+
+      for (tile = gtk_list_item_manager_get_first (self->item_manager);
+           tile != NULL;
+           tile = gtk_rb_tree_node_get_next (tile))
+        {
+          if (tile->widget && tile->type == GTK_LIST_TILE_HEADER)
+            gtk_list_header_widget_set_factory (GTK_LIST_HEADER_WIDGET (tile->widget), factory);
+        }
+    }
+
+  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_HEADER_FACTORY]);
+}
+
 /**
  * gtk_list_view_set_show_separators: (attributes org.gtk.Method.set_property=show-separators)
  * @self: a `GtkListView`
@@ -1139,7 +1248,7 @@ gtk_list_view_set_single_click_activate (GtkListView *self,
        tile != NULL;
        tile = gtk_rb_tree_node_get_next (tile))
     {
-      if (tile->widget)
+      if (tile->widget && tile->type == GTK_LIST_TILE_ITEM)
         gtk_list_factory_widget_set_single_click_activate (GTK_LIST_FACTORY_WIDGET (tile->widget), single_click_activate);
     }
 

gtk/gtklistview.h

@@ -57,6 +57,13 @@ GDK_AVAILABLE_IN_ALL
 GtkListItemFactory *
                 gtk_list_view_get_factory                       (GtkListView            *self);
 
+GDK_AVAILABLE_IN_4_12
+void            gtk_list_view_set_header_factory                (GtkListView            *self,
+                                                                 GtkListItemFactory     *factory);
+GDK_AVAILABLE_IN_4_12
+GtkListItemFactory *
+                gtk_list_view_get_header_factory                (GtkListView            *self);
+
 GDK_AVAILABLE_IN_ALL
 void            gtk_list_view_set_show_separators               (GtkListView            *self,
                                                                  gboolean                show_separators);

gtk/gtklistviewprivate.h

@@ -30,6 +30,7 @@ struct _GtkListView
 
   GtkListItemManager *item_manager;
   GtkListItemFactory *factory;
+  GtkListItemFactory *header_factory;
   gboolean show_separators;
   gboolean single_click_activate;
 };

gtk/meson.build

@@ -271,7 +271,9 @@ gtk_public_sources = files([
   'gtklinkbutton.c',
   'gtklistbox.c',
   'gtklistfactorywidget.c',
+  'gtklistheader.c',
   'gtklistheaderbase.c',
+  'gtklistheaderwidget.c',
   'gtklistitem.c',
   'gtklistitembase.c',
   'gtklistitemfactory.c',
@@ -520,6 +522,7 @@ gtk_public_headers = files([
   'gtklinkbutton.h',
   'gtklistbase.h',
   'gtklistbox.h',
+  'gtklistheader.h',
   'gtklistitem.h',
   'gtklistitemfactory.h',
   'gtklistview.h',