[gtk/wip/otte/listview: 325/327] gtk: Add GtkSingleSelection

[Benjamin Otte <otte src gnome org>]

commit 2b780de34209e916d49bf6023f2f472dbeeb6c61
Author: Benjamin Otte <otte redhat com>
Date:   Wed Oct 3 18:51:52 2018 +0200

    gtk: Add GtkSingleSelection
    
    GtkSingleSelection is a GtkSelectionModel that allows selecting a single
    item.

 gtk/gtk.h                |   1 +
 gtk/gtksingleselection.c | 566 +++++++++++++++++++++++++++++++++++++++++++++++
 gtk/gtksingleselection.h |  65 ++++++
 gtk/meson.build          |   2 +
 4 files changed, 634 insertions(+)
---
diff --git a/gtk/gtk.h b/gtk/gtk.h
index d225841217..bcd144a780 100644
--- a/gtk/gtk.h
+++ b/gtk/gtk.h
@@ -199,6 +199,7 @@
 #include <gtk/gtkshortcutsshortcut.h>
 #include <gtk/gtkshortcutswindow.h>
 #include <gtk/gtkshow.h>
+#include <gtk/gtksingleselection.h>
 #include <gtk/gtkslicelistmodel.h>
 #include <gtk/gtksnapshot.h>
 #include <gtk/gtksortlistmodel.h>
diff --git a/gtk/gtksingleselection.c b/gtk/gtksingleselection.c
new file mode 100644
index 0000000000..b6ec5d7266
--- /dev/null
+++ b/gtk/gtksingleselection.c
@@ -0,0 +1,566 @@
+/*
+ * 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 "gtksingleselection.h"
+
+#include "gtkintl.h"
+#include "gtkselectionmodel.h"
+
+/**
+ * SECTION:gtksingleselection
+ * @Short_description: A selection model that allows selecting a single item
+ * @Title: GtkSingleSelection
+ * @see_also: #GtkSelectionModel
+ *
+ * GtkSingleSelection is an implementation of the #GtkSelectionModel interface 
+ * that allows selecting a single element. It is the default selection method
+ * used by list widgets in GTK.
+ */
+struct _GtkSingleSelection
+{
+  GObject parent_instance;
+
+  GListModel *model;
+  guint selected;
+  gpointer selected_item;
+
+  guint autoselect : 1;
+  guint can_unselect : 1;
+};
+
+struct _GtkSingleSelectionClass
+{
+  GObjectClass parent_class;
+};
+
+enum {
+  PROP_0,
+  PROP_AUTOSELECT,
+  PROP_CAN_UNSELECT,
+  PROP_MODEL,
+  PROP_SELECTED,
+
+  N_PROPS,
+};
+
+static GParamSpec *properties[N_PROPS] = { NULL, };
+
+static GType
+gtk_single_selection_get_item_type (GListModel *list)
+{
+  GtkSingleSelection *self = GTK_SINGLE_SELECTION (list);
+
+  return g_list_model_get_item_type (self->model);
+}
+
+static guint
+gtk_single_selection_get_n_items (GListModel *list)
+{
+  GtkSingleSelection *self = GTK_SINGLE_SELECTION (list);
+
+  return g_list_model_get_n_items (self->model);
+}
+
+static gpointer
+gtk_single_selection_get_item (GListModel *list,
+                               guint       position)
+{
+  GtkSingleSelection *self = GTK_SINGLE_SELECTION (list);
+
+  return g_list_model_get_item (self->model, position);
+}
+
+static void
+gtk_single_selection_list_model_init (GListModelInterface *iface)
+{
+  iface->get_item_type = gtk_single_selection_get_item_type;
+  iface->get_n_items = gtk_single_selection_get_n_items;
+  iface->get_item = gtk_single_selection_get_item;
+}
+
+static gboolean
+gtk_single_selection_is_selected (GtkSelectionModel *model,
+                                  guint              position)
+{
+  GtkSingleSelection *self = GTK_SINGLE_SELECTION (model);
+
+  return self->selected == position;
+}
+
+static gboolean
+gtk_single_selection_select_item (GtkSelectionModel *model,
+                                  guint              position,
+                                  gboolean           exclusive)
+{
+  GtkSingleSelection *self = GTK_SINGLE_SELECTION (model);
+
+  /* XXX: Should we check that position < n_items here? */
+  gtk_single_selection_set_selected (self, position);
+
+  return TRUE;
+}
+
+static gboolean
+gtk_single_selection_unselect_item (GtkSelectionModel *model,
+                                    guint              position)
+{
+  GtkSingleSelection *self = GTK_SINGLE_SELECTION (model);
+
+  if (!self->can_unselect)
+    return FALSE;
+
+  if (self->selected == position)
+    gtk_single_selection_set_selected (self, GTK_INVALID_LIST_POSITION);
+
+  return TRUE;
+}
+
+static void
+gtk_single_selection_selection_model_init (GtkSelectionModelInterface *iface)
+{
+  iface->is_selected = gtk_single_selection_is_selected; 
+  iface->select_item = gtk_single_selection_select_item; 
+  iface->unselect_item = gtk_single_selection_unselect_item; 
+}
+
+G_DEFINE_TYPE_EXTENDED (GtkSingleSelection, gtk_single_selection, G_TYPE_OBJECT, 0,
+                        G_IMPLEMENT_INTERFACE (G_TYPE_LIST_MODEL,
+                                               gtk_single_selection_list_model_init)
+                        G_IMPLEMENT_INTERFACE (GTK_TYPE_SELECTION_MODEL,
+                                               gtk_single_selection_selection_model_init))
+
+static void
+gtk_single_selection_items_changed_cb (GListModel         *model,
+                                       guint               position,
+                                       guint               removed,
+                                       guint               added,
+                                       GtkSingleSelection *self)
+{
+  gboolean emit_selection_changed = FALSE;
+
+  g_object_freeze_notify (G_OBJECT (self));
+
+  if (self->selected_item == NULL)
+    {
+      if (self->autoselect)
+        {
+          self->selected_item = g_list_model_get_item (self->model, 0);
+          if (self->selected_item)
+            {
+              self->selected = 0;
+              g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_SELECTED]);
+            }
+        }
+    }
+  else if (self->selected < position)
+    {
+      /* unchanged */
+    }
+  else if (self->selected >= position + removed)
+    {
+      self->selected += added - removed;
+      g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_SELECTED]);
+    }
+  else
+    {
+      guint i;
+
+      for (i = 0; i < added; i++)
+        {
+          gpointer item = g_list_model_get_item (model, position + i);
+          if (item == self->selected_item)
+            {
+              /* the item moved */
+              if (self->selected != position + i)
+                {
+                  self->selected = position + i;
+                  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_SELECTED]);
+                }
+              break;
+            }
+        }
+      if (i == added)
+        {
+          /* the item really was deleted */
+          g_print ("  %u => ☠\n", self->selected);
+          g_clear_object (&self->selected_item);
+          if (self->autoselect)
+            {
+              self->selected = position + (self->selected - position) * added / removed;
+              self->selected_item = g_list_model_get_item (self->model, self->selected);
+              if (self->selected_item == NULL && position > 0)
+                {
+                  self->selected = position - 1;
+                  self->selected_item = g_list_model_get_item (self->model, self->selected);
+                  g_assert (self->selected_item);
+                }
+              emit_selection_changed = TRUE;
+            }
+          else
+            {
+              g_clear_object (&self->selected_item);
+              self->selected = GTK_INVALID_LIST_POSITION;
+            }
+          g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_SELECTED]);
+        }
+    }
+
+  g_list_model_items_changed (G_LIST_MODEL (self), position, removed, added);
+
+  if (emit_selection_changed && self->selected != GTK_INVALID_LIST_POSITION)
+    gtk_selection_model_selection_changed (GTK_SELECTION_MODEL (self), self->selected, 1);
+
+  g_object_thaw_notify (G_OBJECT (self));
+}
+
+static void
+gtk_single_selection_clear_model (GtkSingleSelection *self)
+{
+  if (self->model == NULL)
+    return;
+
+  g_signal_handlers_disconnect_by_func (self->model, 
+                                        gtk_single_selection_items_changed_cb,
+                                        self);
+  g_clear_object (&self->model);
+}
+
+static void
+gtk_single_selection_set_property (GObject      *object,
+                                   guint         prop_id,
+                                   const GValue *value,
+                                   GParamSpec   *pspec)
+
+{
+  GtkSingleSelection *self = GTK_SINGLE_SELECTION (object);
+
+  switch (prop_id)
+    {
+    case PROP_AUTOSELECT:
+      gtk_single_selection_set_autoselect (self, g_value_get_boolean (value));
+      break;
+
+    case PROP_CAN_UNSELECT:
+      gtk_single_selection_set_can_unselect (self, g_value_get_boolean (value));
+      break;
+
+    case PROP_MODEL:
+      self->model = g_value_dup_object (value);
+      g_warn_if_fail (self->model != NULL);
+      g_signal_connect (self->model,
+                        "items-changed",
+                        G_CALLBACK (gtk_single_selection_items_changed_cb),
+                        self);
+      if (self->autoselect)
+        gtk_single_selection_set_selected (self, 0);
+      break;
+
+    case PROP_SELECTED:
+      gtk_single_selection_set_selected (self, g_value_get_uint (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+gtk_single_selection_get_property (GObject    *object,
+                                   guint       prop_id,
+                                   GValue     *value,
+                                   GParamSpec *pspec)
+{
+  GtkSingleSelection *self = GTK_SINGLE_SELECTION (object);
+
+  switch (prop_id)
+    {
+    case PROP_AUTOSELECT:
+      g_value_set_boolean (value, self->autoselect);
+      break;
+
+    case PROP_CAN_UNSELECT:
+      g_value_set_boolean (value, self->can_unselect);
+      break;
+    case PROP_MODEL:
+      g_value_set_object (value, self->model);
+      break;
+
+    case PROP_SELECTED:
+      g_value_set_uint (value, self->selected);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+gtk_single_selection_dispose (GObject *object)
+{
+  GtkSingleSelection *self = GTK_SINGLE_SELECTION (object);
+
+  gtk_single_selection_clear_model (self);
+
+  self->selected = GTK_INVALID_LIST_POSITION;
+  g_clear_object (&self->selected_item);
+
+  G_OBJECT_CLASS (gtk_single_selection_parent_class)->dispose (object);
+}
+
+static void
+gtk_single_selection_class_init (GtkSingleSelectionClass *klass)
+{
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+
+  gobject_class->get_property = gtk_single_selection_get_property;
+  gobject_class->set_property = gtk_single_selection_set_property;
+  gobject_class->dispose = gtk_single_selection_dispose;
+
+  /**
+   * GtkSingleSelection:autoselect
+   *
+   * If the selection will always select an item
+   */
+  properties[PROP_AUTOSELECT] =
+    g_param_spec_boolean ("autoselect",
+                          P_("Autoselect"),
+                          P_("If the selection will always select an item"),
+                          TRUE,
+                          G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
+
+  /**
+   * GtkSingleSelection:can-unselect
+   *
+   * If unselecting the selected item is allowed
+   */
+  properties[PROP_CAN_UNSELECT] =
+    g_param_spec_boolean ("can-unselect",
+                          P_("Can unselect"),
+                          P_("If unselecting the selected item is allowed"),
+                          FALSE,
+                          G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
+
+  /**
+   * GtkSingleSelection:model
+   *
+   * The list managed by this selection
+   */
+  properties[PROP_MODEL] =
+    g_param_spec_object ("model",
+                         P_("Model"),
+                         P_("List managed by this selection"),
+                         G_TYPE_LIST_MODEL,
+                         G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_EXPLICIT_NOTIFY | 
G_PARAM_STATIC_STRINGS);
+
+  /**
+   * GtkSingleSelection:selected
+   *
+   * Position of the selected item
+   */
+  properties[PROP_SELECTED] =
+    g_param_spec_uint ("selected",
+                       P_("Selected"),
+                       P_("Position of the selected item"),
+                       0, G_MAXUINT, GTK_INVALID_LIST_POSITION,
+                       G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
+
+  g_object_class_install_properties (gobject_class, N_PROPS, properties);
+}
+
+static void
+gtk_single_selection_init (GtkSingleSelection *self)
+{
+  self->selected = GTK_INVALID_LIST_POSITION;
+  self->autoselect = TRUE;
+}
+
+/**
+ * gtk_single_selection_new:
+ * @model: (transfer none): the #GListModel to manage
+ *
+ * Creates a new selection to handle @model.
+ *
+ * Returns: (transfer full) (type GtkSingleSelection): a new #GtkSingleSelection
+ **/
+GListModel *
+gtk_single_selection_new (GListModel *model)
+{
+  g_return_val_if_fail (G_IS_LIST_MODEL (model), NULL);
+
+  return g_object_new (GTK_TYPE_SINGLE_SELECTION,
+                       "model", model,
+                       NULL);
+}
+
+/**
+ * gtk_single_selection_get_selected:
+ * @self: a #GtkSingleSelection
+ *
+ * Gets the position of the selected item. If no item is selected,
+ * #GTK_INVALID_LIST_POSITION is returned.
+ *
+ * Returns: The position of the selected item
+ **/
+guint
+gtk_single_selection_get_selected (GtkSingleSelection *self)
+{
+  g_return_val_if_fail (GTK_IS_SINGLE_SELECTION (self), GTK_INVALID_LIST_POSITION);
+
+  return self->selected;
+}
+
+/**
+ * gtk_single_selection_set_selected:
+ * @self: a #GtkSingleSelection
+ * @position: the item to select or #GTK_INVALID_LIST_POSITION
+ *
+ * Selects the item at the given position. If the list does not have an item at
+ * @position or #GTK_INVALID_LIST_POSITION is given, the behavior depends on the
+ * value of the GtkSingleSelection:autoselect property: If it is set, no change
+ * will occur and the old item will stay selected. If it is unset, the selection
+ * will be unset and no item will be selected.
+ **/
+void
+gtk_single_selection_set_selected (GtkSingleSelection *self,
+                                   guint               position)
+{
+  gpointer new_selected;
+  guint old_position;
+
+  g_return_if_fail (GTK_IS_SINGLE_SELECTION (self));
+
+  if (self->selected == position)
+    return;
+
+  new_selected = g_list_model_get_item (self->model, position);
+  if (new_selected == NULL)
+    position = GTK_INVALID_LIST_POSITION;
+
+  if (self->selected == position)
+    return;
+
+  old_position = self->selected;
+  self->selected = position;
+  g_clear_object (&self->selected_item);
+  self->selected_item = new_selected;
+
+  if (old_position == GTK_INVALID_LIST_POSITION)
+    gtk_selection_model_selection_changed (GTK_SELECTION_MODEL (self), position, 1);
+  else if (position == GTK_INVALID_LIST_POSITION)
+    gtk_selection_model_selection_changed (GTK_SELECTION_MODEL (self), old_position, 1);
+  else if (position < old_position)
+    gtk_selection_model_selection_changed (GTK_SELECTION_MODEL (self), position, old_position - position + 
1);
+  else
+    gtk_selection_model_selection_changed (GTK_SELECTION_MODEL (self), old_position, position - old_position 
+ 1);
+}
+
+/**
+ * gtk_single_selection_get_autoselect:
+ * @self: a #GtkSingleSelection
+ *
+ * Checks if autoselect has been enabled or disabled via
+ * gtk_single_selection_set_autoselect().
+ *
+ * Returns: %TRUE if autoselect is enabled
+ **/
+gboolean
+gtk_single_selection_get_autoselect (GtkSingleSelection *self)
+{
+  g_return_val_if_fail (GTK_IS_SINGLE_SELECTION (self), TRUE);
+
+  return self->autoselect;
+}
+
+/**
+ * gtk_single_selection_set_autoselect:
+ * @self: a #GtkSingleSelection
+ * @autoselect: %TRUE to always select an item
+ *
+ * If @autoselect is %TRUE, @self will enforce that an item is always
+ * selected. It will select a new item when the currently selected
+ * item is deleted and it will disallow unselecting the current item.
+ **/
+void
+gtk_single_selection_set_autoselect (GtkSingleSelection *self,
+                                     gboolean            autoselect)
+{
+  g_return_if_fail (GTK_IS_SINGLE_SELECTION (self));
+
+  if (self->autoselect == autoselect)
+    return;
+
+  self->autoselect = autoselect;
+
+  g_object_freeze_notify (G_OBJECT (self));
+  
+  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_AUTOSELECT]);
+
+  if (self->autoselect && !self->selected_item)
+    gtk_single_selection_set_selected (self, 0);
+
+  g_object_thaw_notify (G_OBJECT (self));
+}
+
+/**
+ * gtk_single_selection_get_can_unselect:
+ * @self: a #GtkSingleSelection
+ *
+ * If %TRUE, gtk_selection_model_unselect_item() is supported and allows
+ * unselecting the selected item.
+ *
+ * Returns: %TRUE to support unselecting
+ **/
+gboolean
+gtk_single_selection_get_can_unselect (GtkSingleSelection *self)
+{
+  g_return_val_if_fail (GTK_IS_SINGLE_SELECTION (self), FALSE);
+
+  return self->can_unselect;
+}
+
+/**
+ * gtk_single_selection_set_can_unselect:
+ * @self: a #GtkSingleSelection
+ * @can_unselect: %TRUE to allow unselecting
+ *
+ * If %TRUE, unselecting the current item via
+ * gtk_selection_model_unselect_item() is supported.
+ *
+ * Note that setting GtkSingleSelection:autoselect will cause the
+ * unselecting to not work, so it practically makes no sense to set
+ * both at the same time the same time..
+ **/
+void
+gtk_single_selection_set_can_unselect (GtkSingleSelection *self,
+                                       gboolean            can_unselect)
+{
+  g_return_if_fail (GTK_IS_SINGLE_SELECTION (self));
+
+  if (self->can_unselect == can_unselect)
+    return;
+
+  self->can_unselect = can_unselect;
+
+  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_CAN_UNSELECT]);
+}
+
diff --git a/gtk/gtksingleselection.h b/gtk/gtksingleselection.h
new file mode 100644
index 0000000000..27f1920dd3
--- /dev/null
+++ b/gtk/gtksingleselection.h
@@ -0,0 +1,65 @@
+/*
+ * 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_SINGLE_SELECTION_H__
+#define __GTK_SINGLE_SELECTION_H__
+
+#include <gtk/gtktypes.h>
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_SINGLE_SELECTION (gtk_single_selection_get_type ())
+
+/**
+ * GTK_INVALID_LIST_POSITION:
+ *
+ * The value used to refer to a guaranteed invalid position in a #GListModel. This
+ * value may be returned from some functions, others may accept it as input.
+ * Its interpretion may differ for different functions.
+ *
+ * Refer to each function's documentation for if this value is allowed and what it
+ * does.
+ */
+#define GTK_INVALID_LIST_POSITION (G_MAXUINT)
+
+GDK_AVAILABLE_IN_ALL
+G_DECLARE_FINAL_TYPE (GtkSingleSelection, gtk_single_selection, GTK, SINGLE_SELECTION, GObject)
+
+GDK_AVAILABLE_IN_ALL
+GListModel *    gtk_single_selection_new                (GListModel             *model);
+
+GDK_AVAILABLE_IN_ALL
+guint           gtk_single_selection_get_selected       (GtkSingleSelection     *self);
+GDK_AVAILABLE_IN_ALL
+void            gtk_single_selection_set_selected       (GtkSingleSelection     *self,
+                                                         guint                   position);
+GDK_AVAILABLE_IN_ALL
+gboolean        gtk_single_selection_get_autoselect     (GtkSingleSelection     *self);
+GDK_AVAILABLE_IN_ALL
+void            gtk_single_selection_set_autoselect     (GtkSingleSelection     *self,
+                                                         gboolean                autoselect);
+GDK_AVAILABLE_IN_ALL
+gboolean        gtk_single_selection_get_can_unselect   (GtkSingleSelection     *self);
+GDK_AVAILABLE_IN_ALL
+void            gtk_single_selection_set_can_unselect   (GtkSingleSelection     *self,
+                                                         gboolean                can_unselect);
+
+G_END_DECLS
+
+#endif /* __GTK_SINGLE_SELECTION_H__ */
diff --git a/gtk/meson.build b/gtk/meson.build
index 3e86924bca..f10346e426 100644
--- a/gtk/meson.build
+++ b/gtk/meson.build
@@ -340,6 +340,7 @@ gtk_public_sources = files([
   'gtkshortcutswindow.c',
   'gtkshow.c',
   'gtksidebarrow.c',
+  'gtksingleselection.c',
   'gtksizegroup.c',
   'gtksizerequest.c',
   'gtkslicelistmodel.c',
@@ -578,6 +579,7 @@ gtk_public_headers = files([
   'gtkshortcutsshortcut.h',
   'gtkshortcutswindow.h',
   'gtkshow.h',
+  'gtksingleselection.h',
   'gtksizegroup.h',
   'gtksizerequest.h',
   'gtkslicelistmodel.h',