[gtk/wip/otte/listmodel: 16/22] GtkSliceListModel: add

[Benjamin Otte <otte src gnome org>]

commit caae154fc159390b03a1ff67879ec79dbb44b65a
Author: Benjamin Otte <otte redhat com>
Date:   Wed Sep 12 03:07:24 2018 +0200

    GtkSliceListModel: add

 docs/reference/gtk/gtk4-docs.xml     |   1 +
 docs/reference/gtk/gtk4-sections.txt |  23 ++
 gtk/gtk.h                            |   1 +
 gtk/gtkslicelistmodel.c              | 525 +++++++++++++++++++++++++++++++++++
 gtk/gtkslicelistmodel.h              |  64 +++++
 gtk/meson.build                      |   2 +
 6 files changed, 616 insertions(+)
---
diff --git a/docs/reference/gtk/gtk4-docs.xml b/docs/reference/gtk/gtk4-docs.xml
index b2e7de2c5f..02c1173cab 100644
--- a/docs/reference/gtk/gtk4-docs.xml
+++ b/docs/reference/gtk/gtk4-docs.xml
@@ -46,6 +46,7 @@
       <xi:include href="xml/gtkfilterlistmodel.xml" />
       <xi:include href="xml/gtkflattenlistmodel.xml" />
       <xi:include href="xml/gtkmaplistmodel.xml" />
+      <xi:include href="xml/gtkslicelistmodel.xml" />
       <xi:include href="xml/gtktreelistmodel.xml" />
     </chapter>
 
diff --git a/docs/reference/gtk/gtk4-sections.txt b/docs/reference/gtk/gtk4-sections.txt
index 5410ec67a4..79c32f75a7 100644
--- a/docs/reference/gtk/gtk4-sections.txt
+++ b/docs/reference/gtk/gtk4-sections.txt
@@ -2593,6 +2593,29 @@ GtkSizeGroupPrivate
 gtk_size_group_get_type
 </SECTION>
 
+<SECTION>
+<FILE>gtkslicelistmodel</FILE>
+<TITLE>GtkSliceListModel</TITLE>
+GtkSliceListModel
+gtk_slice_list_model_new
+gtk_slice_list_model_new_for_type
+gtk_slice_list_model_set_model
+gtk_slice_list_model_get_model
+gtk_slice_list_model_set_offset
+gtk_slice_list_model_get_offset
+gtk_slice_list_model_set_size
+gtk_slice_list_model_get_size
+<SUBSECTION Standard>
+GTK_SLICE_LIST_MODEL
+GTK_IS_SLICE_LIST_MODEL
+GTK_TYPE_SLICE_LIST_MODEL
+GTK_SLICE_LIST_MODEL_CLASS
+GTK_IS_SLICE_LIST_MODEL_CLASS
+GTK_SLICE_LIST_MODEL_GET_CLASS
+<SUBSECTION Private>
+gtk_slice_list_model_get_type
+</SECTION>
+
 <SECTION>
 <FILE>gtkspinbutton</FILE>
 <TITLE>GtkSpinButton</TITLE>
diff --git a/gtk/gtk.h b/gtk/gtk.h
index cde9b4a46b..7d45fd791d 100644
--- a/gtk/gtk.h
+++ b/gtk/gtk.h
@@ -195,6 +195,7 @@
 #include <gtk/gtkshortcutsshortcut.h>
 #include <gtk/gtkshortcutswindow.h>
 #include <gtk/gtkshow.h>
+#include <gtk/gtkslicelistmodel.h>
 #include <gtk/gtksnapshot.h>
 #include <gtk/gtkstacksidebar.h>
 #include <gtk/gtksizegroup.h>
diff --git a/gtk/gtkslicelistmodel.c b/gtk/gtkslicelistmodel.c
new file mode 100644
index 0000000000..95c6eaa03d
--- /dev/null
+++ b/gtk/gtkslicelistmodel.c
@@ -0,0 +1,525 @@
+/*
+ * 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 "gtkslicelistmodel.h"
+
+#include "gtkcssrbtreeprivate.h"
+#include "gtkintl.h"
+#include "gtkprivate.h"
+
+/**
+ * SECTION:gtkslicelistmodel
+ * @title: GtkSliceListModel
+ * @short_description: a #GListModel that presents a slice out of a larger list
+ * @see_also: #GListModel
+ *
+ * #GtkSliceListModel is a list model that takes a list model and presents a slice of
+ * that model.
+ *
+ * This is useful when implementing paging by setting the size to the number of elements
+ * per page and updating the offset whenever a different page is opened.
+ */
+
+#define DEFAULT_SIZE 10
+
+enum {
+  PROP_0,
+  PROP_ITEM_TYPE,
+  PROP_MODEL,
+  PROP_OFFSET,
+  PROP_SIZE,
+  NUM_PROPERTIES
+};
+
+struct _GtkSliceListModel
+{
+  GObject parent_instance;
+
+  GType item_type;
+  GListModel *model;
+  guint offset;
+  guint size;
+
+  guint n_items;
+};
+
+struct _GtkSliceListModelClass
+{
+  GObjectClass parent_class;
+};
+
+static GParamSpec *properties[NUM_PROPERTIES] = { NULL, };
+
+static GType
+gtk_slice_list_model_get_item_type (GListModel *list)
+{
+  GtkSliceListModel *self = GTK_SLICE_LIST_MODEL (list);
+
+  return self->item_type;
+}
+
+static guint
+gtk_slice_list_model_get_n_items (GListModel *list)
+{
+  GtkSliceListModel *self = GTK_SLICE_LIST_MODEL (list);
+  guint n_items;
+  
+  if (self->model == NULL)
+    return 0;
+
+  /* XXX: This can be done without calling g_list_model_get_n_items() on the parent model
+   * by checking if model.get_item(offset + size) != NULL */
+  n_items = g_list_model_get_n_items (self->model);
+  if (n_items <= self->offset)
+    return 0;
+
+  n_items -= self->offset;
+  return MIN (n_items, self->size);
+}
+
+static gpointer
+gtk_slice_list_model_get_item (GListModel *list,
+                               guint       position)
+{
+  GtkSliceListModel *self = GTK_SLICE_LIST_MODEL (list);
+
+  if (self->model == NULL)
+    return NULL;
+
+  if (position >= self->size)
+    return NULL;
+
+  return g_list_model_get_item (self->model, position + self->offset);
+}
+
+static void
+gtk_slice_list_model_model_init (GListModelInterface *iface)
+{
+  iface->get_item_type = gtk_slice_list_model_get_item_type;
+  iface->get_n_items = gtk_slice_list_model_get_n_items;
+  iface->get_item = gtk_slice_list_model_get_item;
+}
+
+G_DEFINE_TYPE_WITH_CODE (GtkSliceListModel, gtk_slice_list_model, G_TYPE_OBJECT,
+                         G_IMPLEMENT_INTERFACE (G_TYPE_LIST_MODEL, gtk_slice_list_model_model_init))
+
+static void
+gtk_slice_list_model_items_changed_cb (GListModel        *model,
+                                       guint              position,
+                                       guint              removed,
+                                       guint              added,
+                                       GtkSliceListModel *self)
+{
+  if (position >= self->offset + self->size)
+    return;
+
+  if (position < self->offset)
+    {
+      guint skip = MIN (removed, added);
+      skip = MIN (skip, position - self->offset);
+
+      position += skip;
+      removed -= skip;
+      added -= skip;
+    }
+
+  if (removed == added)
+    {
+      guint changed = removed;
+
+      if (changed == 0)
+        return;
+
+      g_assert (position >= self->offset);
+      position -= self->offset;
+      changed = MIN (changed, self->size) - position;
+
+      g_list_model_items_changed (G_LIST_MODEL (self), position, changed, changed);
+    }
+  else
+    {
+      guint n_after, n_before;
+
+      n_after = g_list_model_get_n_items (self->model);
+      n_before = n_after - added + removed;
+      n_after = CLAMP (n_after, self->offset, self->offset + self->size) - self->offset;
+      n_before = CLAMP (n_before, self->offset, self->offset + self->size) - self->offset;
+
+      g_list_model_items_changed (G_LIST_MODEL (self), 0, n_before, n_after);
+    }
+}
+
+static void
+gtk_slice_list_model_set_property (GObject      *object,
+                                   guint         prop_id,
+                                   const GValue *value,
+                                   GParamSpec   *pspec)
+{
+  GtkSliceListModel *self = GTK_SLICE_LIST_MODEL (object);
+
+  switch (prop_id)
+    {
+    case PROP_ITEM_TYPE:
+      self->item_type = g_value_get_gtype (value);
+      break;
+
+    case PROP_MODEL:
+      gtk_slice_list_model_set_model (self, g_value_get_object (value));
+      break;
+
+    case PROP_OFFSET:
+      gtk_slice_list_model_set_offset (self, g_value_get_uint (value));
+      break;
+
+    case PROP_SIZE:
+      gtk_slice_list_model_set_size (self, g_value_get_uint (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+    }
+}
+
+static void 
+gtk_slice_list_model_get_property (GObject     *object,
+                                   guint        prop_id,
+                                   GValue      *value,
+                                   GParamSpec  *pspec)
+{
+  GtkSliceListModel *self = GTK_SLICE_LIST_MODEL (object);
+
+  switch (prop_id)
+    {
+    case PROP_ITEM_TYPE:
+      g_value_set_gtype (value, self->item_type);
+      break;
+
+    case PROP_MODEL:
+      g_value_set_object (value, self->model);
+      break;
+
+    case PROP_OFFSET:
+      g_value_set_uint (value, self->offset);
+      break;
+
+    case PROP_SIZE:
+      g_value_set_uint (value, self->size);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+gtk_slice_list_model_clear_model (GtkSliceListModel *self)
+{
+  if (self->model == NULL)
+    return;
+
+  g_signal_handlers_disconnect_by_func (self->model, gtk_slice_list_model_items_changed_cb, self);
+  g_clear_object (&self->model);
+}
+
+static void
+gtk_slice_list_model_dispose (GObject *object)
+{
+  GtkSliceListModel *self = GTK_SLICE_LIST_MODEL (object);
+
+  gtk_slice_list_model_clear_model (self);
+
+  G_OBJECT_CLASS (gtk_slice_list_model_parent_class)->dispose (object);
+};
+
+static void
+gtk_slice_list_model_class_init (GtkSliceListModelClass *class)
+{
+  GObjectClass *gobject_class = G_OBJECT_CLASS (class);
+
+  gobject_class->set_property = gtk_slice_list_model_set_property;
+  gobject_class->get_property = gtk_slice_list_model_get_property;
+  gobject_class->dispose = gtk_slice_list_model_dispose;
+
+  /**
+   * GtkSliceListModel:item-type:
+   *
+   * The #GType for elements of this object
+   */
+  properties[PROP_ITEM_TYPE] =
+      g_param_spec_gtype ("item-type",
+                          P_("Item type"),
+                          P_("The type of elements of this object"),
+                          G_TYPE_OBJECT,
+                          GTK_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_EXPLICIT_NOTIFY);
+
+  /**
+   * GtkSliceListModel:model:
+   *
+   * Child model to take slice from
+   */
+  properties[PROP_MODEL] =
+      g_param_spec_object ("model",
+                           P_("Model"),
+                           P_("Child model to take slice from"),
+                           G_TYPE_LIST_MODEL,
+                           GTK_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);
+
+  /**
+   * GtkSliceListModel:offset:
+   *
+   * Offset of slice
+   */
+  properties[PROP_OFFSET] =
+      g_param_spec_uint ("offset",
+                         P_("Offset"),
+                         P_("Offset of slice"),
+                         0, G_MAXUINT, 0,
+                         GTK_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);
+
+  /**
+   * GtkSliceListModel:size:
+   *
+   * Maximum size of slice
+   */
+  properties[PROP_SIZE] =
+      g_param_spec_uint ("size",
+                         P_("Size"),
+                         P_("Maximum size of slice"),
+                         0, G_MAXUINT, DEFAULT_SIZE,
+                         GTK_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);
+
+  g_object_class_install_properties (gobject_class, NUM_PROPERTIES, properties);
+}
+
+static void
+gtk_slice_list_model_init (GtkSliceListModel *self)
+{
+  self->size = DEFAULT_SIZE;
+}
+
+/**
+ * gtk_slice_list_model_new:
+ * @model: (transfer none): The model to use
+ * @offset: the offset of the slice
+ * @size: maximum size of the slice
+ *
+ * Creates a new slice model that presents the slice from @offset to
+ * @offset + @size our of the given @model.
+ *
+ * Returns: A new #GtkSliceListModel
+ **/
+GtkSliceListModel *
+gtk_slice_list_model_new (GListModel *model,
+                          guint       offset,
+                          guint       size)
+{
+  g_return_val_if_fail (G_IS_LIST_MODEL (model), NULL);
+
+  return g_object_new (GTK_TYPE_SLICE_LIST_MODEL,
+                       "item-type", g_list_model_get_item_type (model),
+                       "model", model,
+                       "offset", offset,
+                       "size", size,
+                       NULL);
+}
+
+/**
+ * gtk_slice_list_model_new_for_type:
+ * @item_type: the type of items
+ *
+ * Creates a new empty #GtkSliceListModel for the given @item_type that
+ * can be set up later.
+ *
+ * Returns: a new empty #GtkSliceListModel
+ **/
+GtkSliceListModel *
+gtk_slice_list_model_new_for_type (GType item_type)
+{
+  g_return_val_if_fail (g_type_is_a (item_type, G_TYPE_OBJECT), NULL);
+
+  return g_object_new (GTK_TYPE_SLICE_LIST_MODEL,
+                       "item-type", item_type,
+                       NULL);
+}
+
+/**
+ * gtk_slice_list_model_set_model:
+ * @self: a #GtkSliceListModel
+ * @model: (allow-none): The model to be sliceped
+ *
+ * Sets the model to show a slice of. The model's item type must conform
+ * to @self's item type.
+ *
+ **/
+void
+gtk_slice_list_model_set_model (GtkSliceListModel *self,
+                                GListModel      *model)
+{
+  guint removed, added;
+
+  g_return_if_fail (GTK_IS_SLICE_LIST_MODEL (self));
+  g_return_if_fail (model == NULL || G_IS_LIST_MODEL (model));
+
+  if (self->model == model)
+    return;
+
+  removed = g_list_model_get_n_items (G_LIST_MODEL (self));
+  gtk_slice_list_model_clear_model (self);
+
+  if (model)
+    {
+      self->model = g_object_ref (model);
+      g_signal_connect (model, "items-changed", G_CALLBACK (gtk_slice_list_model_items_changed_cb), self);
+      added = g_list_model_get_n_items (G_LIST_MODEL (self));
+    }
+  else
+    {
+      added = 0;
+    }
+
+  if (removed > 0 || added > 0)
+    g_list_model_items_changed (G_LIST_MODEL (self), 0, removed, added);
+
+  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_MODEL]);
+}
+
+/**
+ * gtk_slice_list_model_get_model:
+ * @self: a #GtkSliceListModel
+ *
+ * Gets the model that is curently being used or %NULL if none.
+ *
+ * Returns: (nullable) (transfer none): The model in use
+ **/
+GListModel *
+gtk_slice_list_model_get_model (GtkSliceListModel *self)
+{
+  g_return_val_if_fail (GTK_IS_SLICE_LIST_MODEL (self), NULL);
+
+  return self->model;
+}
+
+/**
+ * gtk_slice_list_model_set_offset:
+ * @self: a #GtkSliceListModel
+ * @offset: the new offset to use
+ *
+ * Sets the offset into the original model for this slice.
+ *
+ * If the offset is larger than the number of the items in
+ * the sliced model, it will remain unchanged and @self will
+ * be empty.
+ **/
+void
+gtk_slice_list_model_set_offset (GtkSliceListModel *self,
+                                 guint              offset)
+{
+  guint before, after;
+
+  g_return_if_fail (GTK_IS_SLICE_LIST_MODEL (self));
+
+  if (self->offset == offset)
+    return;
+
+  before = g_list_model_get_n_items (G_LIST_MODEL (self));
+
+  self->offset = offset;
+
+  after = g_list_model_get_n_items (G_LIST_MODEL (self));
+
+  if (before > 0 || after > 0)
+    g_list_model_items_changed (G_LIST_MODEL (self), 0, before, after);
+
+  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_OFFSET]);
+}
+
+/**
+ * gtk_slice_list_model_get_offset:
+ * @self: a #GtkSliceListModel
+ *
+ * Gets the offset via gtk_slice_list_model_set_offset()
+ *
+ * Returns: The offset
+ **/
+guint
+gtk_slice_list_model_get_offset (GtkSliceListModel *self)
+{
+  g_return_val_if_fail (GTK_IS_SLICE_LIST_MODEL (self), 0);
+
+  return self->offset;
+}
+
+/**
+ * gtk_slice_list_model_set_offset:
+ * @self: a #GtkSliceListModel
+ * @size: the maximum size
+ *
+ * Sets the maximum size. So @self will never have more items
+ * than @size.
+ *
+ * It can however have fewer items if the offset is to large or
+ * the model sliced from doesn't have enough items.
+ */
+void
+gtk_slice_list_model_set_size (GtkSliceListModel *self,
+                               guint              size)
+{
+  guint before, after;
+
+  g_return_if_fail (GTK_IS_SLICE_LIST_MODEL (self));
+
+  if (self->size == size)
+    return;
+
+  before = g_list_model_get_n_items (G_LIST_MODEL (self));
+
+  self->size = size;
+
+  after = g_list_model_get_n_items (G_LIST_MODEL (self));
+
+  if (before > after)
+    g_list_model_items_changed (G_LIST_MODEL (self), after, before - after, 0);
+  else if (before < after)
+    g_list_model_items_changed (G_LIST_MODEL (self), before, 0, after - before);
+  /* else nothing */
+
+  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_SIZE]);
+}
+
+/**
+ * gtk_slice_list_model_get_size:
+ * @self: a #GtkSliceListModel
+ *
+ * Gets thje size set via gtk_slice_list_model_set_size().
+ *
+ * Returns: The size
+ **/
+guint
+gtk_slice_list_model_get_size (GtkSliceListModel *self)
+{
+  g_return_val_if_fail (GTK_IS_SLICE_LIST_MODEL (self), DEFAULT_SIZE);
+
+  return self->size;
+}
+
+
diff --git a/gtk/gtkslicelistmodel.h b/gtk/gtkslicelistmodel.h
new file mode 100644
index 0000000000..837e67ef7a
--- /dev/null
+++ b/gtk/gtkslicelistmodel.h
@@ -0,0 +1,64 @@
+/*
+ * 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_SLICE_LIST_MODEL_H__
+#define __GTK_SLICE_LIST_MODEL_H__
+
+
+#if !defined (__GTK_H_INSIDE__) && !defined (GTK_COMPILATION)
+#error "Only <gtk/gtk.h> can be included directly."
+#endif
+
+#include <gio/gio.h>
+#include <gtk/gtkwidget.h>
+
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_SLICE_LIST_MODEL (gtk_slice_list_model_get_type ())
+
+GDK_AVAILABLE_IN_ALL
+G_DECLARE_FINAL_TYPE (GtkSliceListModel, gtk_slice_list_model, GTK, SLICE_LIST_MODEL, GObject)
+
+GDK_AVAILABLE_IN_ALL
+GtkSliceListModel *     gtk_slice_list_model_new                (GListModel             *model,
+                                                                 guint                   offset,
+                                                                 guint                   size);
+GDK_AVAILABLE_IN_ALL
+GtkSliceListModel *     gtk_slice_list_model_new_for_type       (GType                   item_type);
+
+GDK_AVAILABLE_IN_ALL
+void                    gtk_slice_list_model_set_model          (GtkSliceListModel      *self,
+                                                                 GListModel             *model);
+GDK_AVAILABLE_IN_ALL
+GListModel *            gtk_slice_list_model_get_model          (GtkSliceListModel      *self);
+GDK_AVAILABLE_IN_ALL
+void                    gtk_slice_list_model_set_offset         (GtkSliceListModel      *self,
+                                                                 guint                   offset);
+GDK_AVAILABLE_IN_ALL
+guint                   gtk_slice_list_model_get_offset         (GtkSliceListModel      *self);
+GDK_AVAILABLE_IN_ALL
+void                    gtk_slice_list_model_set_size           (GtkSliceListModel      *self,
+                                                                 guint                   size);
+GDK_AVAILABLE_IN_ALL
+guint                   gtk_slice_list_model_get_size           (GtkSliceListModel      *self);
+
+G_END_DECLS
+
+#endif /* __GTK_SLICE_LIST_MODEL_H__ */
diff --git a/gtk/meson.build b/gtk/meson.build
index 386d72dbed..4246560bdc 100644
--- a/gtk/meson.build
+++ b/gtk/meson.build
@@ -338,6 +338,7 @@ gtk_public_sources = files([
   'gtksidebarrow.c',
   'gtksizegroup.c',
   'gtksizerequest.c',
+  'gtkslicelistmodel.c',
   'gtkspinbutton.c',
   'gtksnapshot.c',
   'gtkspinner.c',
@@ -571,6 +572,7 @@ gtk_public_headers = files([
   'gtkshow.h',
   'gtksizegroup.h',
   'gtksizerequest.h',
+  'gtkslicelistmodel.h',
   'gtksnapshot.h',
   'gtkspinbutton.h',
   'gtkspinner.h',