[gtk/stack-fixes: 2/6] stack: Provide a selection model

[Matthias Clasen <matthiasc src gnome org>]

commit 30987fc926f49821927b3af1000f608520e00954
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Feb 10 18:22:54 2019 -0500

    stack: Provide a selection model
    
    Make GtkStack expose a selection model for its pages.
    The model can be used to track changes to the pages,
    and to change what child is visible.

 gtk/gtkstack.c | 240 +++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 gtk/gtkstack.h |   5 ++
 2 files changed, 239 insertions(+), 6 deletions(-)
---
diff --git a/gtk/gtkstack.c b/gtk/gtkstack.c
index 5e430f6709..7a1c4cb91f 100644
--- a/gtk/gtkstack.c
+++ b/gtk/gtkstack.c
@@ -30,6 +30,8 @@
 #include "gtksettingsprivate.h"
 #include "gtksnapshot.h"
 #include "gtkwidgetprivate.h"
+#include "gtksingleselection.h"
+#include "gtklistlistmodelprivate.h"
 #include "a11y/gtkstackaccessible.h"
 #include "a11y/gtkstackaccessibleprivate.h"
 #include <math.h>
@@ -138,6 +140,8 @@ typedef struct {
 
   GtkStackTransitionType active_transition_type;
 
+  GtkSelectionModel *pages;
+
 } GtkStackPrivate;
 
 static void gtk_stack_buildable_interface_init (GtkBuildableIface *iface);
@@ -432,6 +436,124 @@ gtk_stack_page_class_init (GtkStackPageClass *class)
   g_object_class_install_properties (object_class, LAST_CHILD_PROP, stack_child_props);
 }
 
+#define GTK_TYPE_STACK_PAGES (gtk_stack_pages_get_type ())
+G_DECLARE_FINAL_TYPE (GtkStackPages, gtk_stack_pages, GTK, STACK_PAGES, GObject)
+
+struct _GtkStackPages
+{
+  GObject parent_instance;
+  GtkStack *stack;
+};
+
+struct _GtkStackPagesClass
+{
+  GObjectClass parent_class;
+};
+
+static GType
+gtk_stack_pages_get_item_type (GListModel *model)
+{
+  return GTK_TYPE_STACK_PAGE;
+}
+
+static guint
+gtk_stack_pages_get_n_items (GListModel *model)
+{
+  GtkStackPages *pages = GTK_STACK_PAGES (model);
+  GtkStackPrivate *priv = gtk_stack_get_instance_private (pages->stack);
+
+  return g_list_length (priv->children);
+}
+
+static gpointer
+gtk_stack_pages_get_item (GListModel *model,
+                          guint       position)
+{
+  GtkStackPages *pages = GTK_STACK_PAGES (model);
+  GtkStackPrivate *priv = gtk_stack_get_instance_private (pages->stack);
+  GtkStackPage *page;
+
+  page = g_list_nth_data (priv->children, position);
+
+  return g_object_ref (page);
+}
+
+static void
+gtk_stack_pages_list_model_init (GListModelInterface *iface)
+{
+  iface->get_item_type = gtk_stack_pages_get_item_type;
+  iface->get_n_items = gtk_stack_pages_get_n_items;
+  iface->get_item = gtk_stack_pages_get_item;
+}
+
+static gboolean
+gtk_stack_pages_is_selected (GtkSelectionModel *model,
+                             guint              position)
+{
+  GtkStackPages *pages = GTK_STACK_PAGES (model);
+  GtkStackPrivate *priv = gtk_stack_get_instance_private (pages->stack);
+  GtkStackPage *page;
+
+  page = GTK_STACK_PAGE (g_list_model_get_item (G_LIST_MODEL (model), position));
+  g_object_unref (page);
+
+  return page == priv->visible_child;
+}
+
+static void set_visible_child (GtkStack               *stack,
+                               GtkStackPage           *child_info,
+                               GtkStackTransitionType  transition_type,
+                               guint                   transition_duration);
+
+static gboolean
+gtk_stack_pages_select_item (GtkSelectionModel *model,
+                             guint              position,
+                             gboolean           exclusive)
+{
+  GtkStackPages *pages = GTK_STACK_PAGES (model);
+  GtkStackPrivate *priv = gtk_stack_get_instance_private (pages->stack);
+  GtkStackPage *page;
+
+  page = GTK_STACK_PAGE (g_list_model_get_item (G_LIST_MODEL (model), position));
+  g_object_unref (page);
+
+  set_visible_child (pages->stack, page, priv->transition_type, priv->transition_duration);
+
+  return TRUE;
+}
+
+static void
+gtk_stack_pages_selection_model_init (GtkSelectionModelInterface *iface)
+{
+  iface->is_selected = gtk_stack_pages_is_selected;
+  iface->select_item = gtk_stack_pages_select_item;
+}
+
+G_DEFINE_TYPE_WITH_CODE (GtkStackPages, gtk_stack_pages, G_TYPE_OBJECT,
+                         G_IMPLEMENT_INTERFACE (G_TYPE_LIST_MODEL, gtk_stack_pages_list_model_init)
+                         G_IMPLEMENT_INTERFACE (GTK_TYPE_SELECTION_MODEL, 
gtk_stack_pages_selection_model_init))
+
+static void
+gtk_stack_pages_init (GtkStackPages *pages)
+{
+}
+
+static void
+gtk_stack_pages_class_init (GtkStackPagesClass *class)
+{
+}
+
+static GtkStackPages *
+gtk_stack_pages_new (GtkStack *stack)
+{
+  GtkStackPages *pages;
+
+  pages = g_object_new (GTK_TYPE_STACK_PAGES, NULL);
+  pages->stack = stack;
+
+  return pages;
+}
+
 static void     gtk_stack_add                            (GtkContainer  *widget,
                                                           GtkWidget     *child);
 static void     gtk_stack_remove                         (GtkContainer  *widget,
@@ -455,6 +577,7 @@ static void     gtk_stack_measure                        (GtkWidget      *widget
                                                           int            *natural,
                                                           int            *minimum_baseline,
                                                           int            *natural_baseline);
+static void     gtk_stack_dispose                        (GObject       *obj);
 static void     gtk_stack_finalize                       (GObject       *obj);
 static void     gtk_stack_get_property                   (GObject       *object,
                                                           guint          property_id,
@@ -490,6 +613,29 @@ gtk_stack_buildable_interface_init (GtkBuildableIface *iface)
   iface->add_child = gtk_stack_buildable_add_child;
 }
 
+static void stack_remove (GtkStack  *stack,
+                          GtkWidget *child,
+                          gboolean   in_dispose);
+
+static void
+remove_child (GtkWidget *child, gpointer user_data)
+{
+  stack_remove (GTK_STACK (user_data), child, TRUE);
+}
+
+static void
+gtk_stack_dispose (GObject *obj)
+{
+  GtkStack *stack = GTK_STACK (obj);
+  GtkStackPrivate *priv = gtk_stack_get_instance_private (stack);
+
+  if (priv->pages)
+    g_list_model_items_changed (G_LIST_MODEL (priv->pages), 0, g_list_length (priv->children), 0);
+  gtk_container_foreach (GTK_CONTAINER (obj), remove_child, obj);
+
+  G_OBJECT_CLASS (gtk_stack_parent_class)->dispose (obj);
+}
+
 static void
 gtk_stack_finalize (GObject *obj)
 {
@@ -595,6 +741,7 @@ gtk_stack_class_init (GtkStackClass *klass)
 
   object_class->get_property = gtk_stack_get_property;
   object_class->set_property = gtk_stack_set_property;
+  object_class->dispose = gtk_stack_dispose;
   object_class->finalize = gtk_stack_finalize;
 
   widget_class->size_allocate = gtk_stack_size_allocate;
@@ -1052,6 +1199,8 @@ set_visible_child (GtkStack               *stack,
   GtkWidget *toplevel;
   GtkWidget *focus;
   gboolean contains_focus = FALSE;
+  guint old_pos = 0;
+  guint new_pos = 0;
 
   /* if we are being destroyed, do not bother with transitions
    * and notifications
@@ -1076,6 +1225,22 @@ set_visible_child (GtkStack               *stack,
   if (child_info == priv->visible_child)
     return;
 
+  if (child_info == NULL)
+    return;
+
+  if (priv->pages)
+    {
+      guint position;
+      for (l = priv->children, position = 0; l != NULL; l = l->next, position++)
+        {
+          info = l->data;
+          if (info == priv->visible_child)
+            old_pos = position;
+          else if (info == child_info)
+            new_pos = position;
+        }
+    }
+
   toplevel = gtk_widget_get_toplevel (widget);
   if (GTK_IS_WINDOW (toplevel))
     {
@@ -1169,6 +1334,11 @@ set_visible_child (GtkStack               *stack,
   g_object_notify_by_pspec (G_OBJECT (stack),
                             stack_props[PROP_VISIBLE_CHILD_NAME]);
 
+  if (priv->pages)
+    gtk_selection_model_selection_changed (priv->pages,
+                                           MIN (old_pos, new_pos), 
+                                           MAX (old_pos, new_pos) - MIN (old_pos, new_pos) + 1);
+
   gtk_stack_start_transition (stack, transition_type, transition_duration);
 }
 
@@ -1305,6 +1475,9 @@ gtk_stack_add_page (GtkStack     *stack,
   gtk_widget_set_child_visible (child_info->widget, FALSE);
   gtk_widget_set_parent (child_info->widget, GTK_WIDGET (stack));
 
+  if (priv->pages)
+    g_list_model_items_changed (G_LIST_MODEL (priv->pages), g_list_length (priv->children) - 1, 0, 1);
+
   g_signal_connect (child_info->widget, "notify::visible",
                     G_CALLBACK (stack_child_visibility_notify_cb), stack);
 
@@ -1319,10 +1492,10 @@ gtk_stack_add_page (GtkStack     *stack,
 }
 
 static void
-gtk_stack_remove (GtkContainer *container,
-                  GtkWidget    *child)
+stack_remove (GtkStack  *stack,
+              GtkWidget *child,
+              gboolean   in_dispose)
 {
-  GtkStack *stack = GTK_STACK (container);
   GtkStackPrivate *priv = gtk_stack_get_instance_private (stack);
   GtkStackPage *child_info;
   gboolean was_visible;
@@ -1332,7 +1505,7 @@ gtk_stack_remove (GtkContainer *container,
     return;
 
   priv->children = g_list_remove (priv->children, child_info);
-
+  
   g_signal_handlers_disconnect_by_func (child,
                                         stack_child_visibility_notify_cb,
                                         stack);
@@ -1342,7 +1515,12 @@ gtk_stack_remove (GtkContainer *container,
   child_info->widget = NULL;
 
   if (priv->visible_child == child_info)
-    set_visible_child (stack, NULL, priv->transition_type, priv->transition_duration);
+    {
+      if (in_dispose)
+        priv->visible_child = NULL;
+      else
+        set_visible_child (stack, NULL, priv->transition_type, priv->transition_duration);
+    }
 
   if (priv->last_visible_child == child_info)
     priv->last_visible_child = NULL;
@@ -1351,10 +1529,33 @@ gtk_stack_remove (GtkContainer *container,
 
   g_object_unref (child_info);
 
-  if ((priv->hhomogeneous || priv->vhomogeneous) && was_visible)
+  if (!in_dispose &&
+      (priv->hhomogeneous || priv->vhomogeneous) &&
+      was_visible)
     gtk_widget_queue_resize (GTK_WIDGET (stack));
 }
 
+static void
+gtk_stack_remove (GtkContainer *container,
+                  GtkWidget    *child)
+{
+  GtkStackPrivate *priv = gtk_stack_get_instance_private (GTK_STACK (container));
+  GList *l;
+  guint position;
+
+  for (l = priv->children, position = 0; l; l = l->next, position++)
+    {
+      GtkStackPage *page = l->data;
+      if (page->widget == child)
+        break;
+    }
+
+  stack_remove (GTK_STACK (container), child, FALSE);
+
+  if (priv->pages)
+    g_list_model_items_changed (G_LIST_MODEL (priv->pages), position, 1, 0);
+}
+
 /**
  * gtk_stack_get_page:
  * @stack: a #GtkStack
@@ -2318,3 +2519,30 @@ gtk_stack_init (GtkStack *stack)
   priv->transition_duration = 200;
   priv->transition_type = GTK_STACK_TRANSITION_TYPE_NONE;
 }
+
+/**
+ * gtk_stack_get_pages:
+ * @stack: a #GtkStack
+ *
+ * Returns a #GListModel that contains the pages of the stack,
+ * and can be used to keep and up-to-date view. The model also
+ * implements #GtkSelectionModel and can be used to track and
+ * modify the visible page..
+ *
+ * Returns: (transfer full): a #GtkSelectionModel for the stack's children
+ */
+GtkSelectionModel *
+gtk_stack_get_pages (GtkStack *stack)
+{
+  GtkStackPrivate *priv = gtk_stack_get_instance_private (stack);
+
+  g_return_val_if_fail (GTK_IS_STACK (stack), NULL);
+
+  if (priv->pages)
+    return g_object_ref (priv->pages);
+
+  priv->pages = GTK_SELECTION_MODEL (gtk_stack_pages_new (stack));
+  g_object_add_weak_pointer (G_OBJECT (priv->pages), (gpointer *)&priv->pages);
+
+  return priv->pages;
+}
diff --git a/gtk/gtkstack.h b/gtk/gtkstack.h
index 6379328041..658ef8bb6a 100644
--- a/gtk/gtkstack.h
+++ b/gtk/gtkstack.h
@@ -27,6 +27,7 @@
 #endif
 
 #include <gtk/gtkcontainer.h>
+#include <gtk/gtkselectionmodel.h>
 
 G_BEGIN_DECLS
 
@@ -155,6 +156,10 @@ void                   gtk_stack_set_interpolate_size    (GtkStack *stack,
                                                           gboolean  interpolate_size);
 GDK_AVAILABLE_IN_ALL
 gboolean               gtk_stack_get_interpolate_size    (GtkStack *stack);
+
+GDK_AVAILABLE_IN_ALL
+GtkSelectionModel *    gtk_stack_get_pages               (GtkStack *stack);
+
 G_END_DECLS
 
 #endif