[gtk/wip/otte/listview: 121/199] listitem: Change focus handling

[Benjamin Otte <otte src gnome org>]

commit 7e9339e45711a64ebecb7671eb7032e8bf0a2324
Author: Benjamin Otte <otte redhat com>
Date:   Tue Oct 15 04:18:10 2019 +0200

    listitem: Change focus handling
    
    Focus in the listitem now works like this:
    1. If any child can take focus, do not ever attempt
       to take focus.
    2. Otherwise, if this item is selectable or activatable,
       allow focusing this widget.
    
    This makes sure every item in a list is focusable for
    activation and selection handling, but no useless widgets
    get focused and moving focus is as fast as possible.

 gtk/gtklistitem.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 48 insertions(+), 2 deletions(-)
---
diff --git a/gtk/gtklistitem.c b/gtk/gtklistitem.c
index b01e7d4cfb..46d6dc09e0 100644
--- a/gtk/gtklistitem.c
+++ b/gtk/gtklistitem.c
@@ -86,6 +86,51 @@ G_DEFINE_TYPE (GtkListItem, gtk_list_item, GTK_TYPE_WIDGET)
 
 static GParamSpec *properties[N_PROPS] = { NULL, };
 
+static gboolean
+gtk_list_item_focus (GtkWidget        *widget,
+                     GtkDirectionType  direction)
+{
+  GtkListItem *self = GTK_LIST_ITEM (widget);
+
+  /* The idea of this function is the following:
+   * 1. If any child can take focus, do not ever attempt
+   *    to take focus.
+   * 2. Otherwise, if this item is selectable or activatable,
+   *    allow focusing this widget.
+   *
+   * This makes sure every item in a list is focusable for
+   * activation and selection handling, but no useless widgets
+   * get focused and moving focus is as fast as possible.
+   */
+  if (self->child)
+    {
+      if (gtk_widget_get_focus_child (widget))
+        return FALSE;
+      if (gtk_widget_child_focus (self->child, direction))
+        return TRUE;
+    }
+
+  if (gtk_widget_is_focus (widget))
+    return FALSE;
+
+  if (!gtk_widget_get_can_focus (widget) ||
+      !self->selectable)
+    return FALSE;
+
+  return gtk_widget_grab_focus (widget);
+}
+
+static gboolean
+gtk_list_item_grab_focus (GtkWidget *widget)
+{
+  GtkListItem *self = GTK_LIST_ITEM (widget);
+
+  if (self->child && gtk_widget_grab_focus (self->child))
+    return TRUE;
+
+  return GTK_WIDGET_CLASS (gtk_list_item_parent_class)->grab_focus (widget);
+}
+
 static void
 gtk_list_item_dispose (GObject *object)
 {
@@ -163,6 +208,9 @@ gtk_list_item_class_init (GtkListItemClass *klass)
   GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
   GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
 
+  widget_class->focus = gtk_list_item_focus;
+  widget_class->grab_focus = gtk_list_item_grab_focus;
+
   gobject_class->dispose = gtk_list_item_dispose;
   gobject_class->get_property = gtk_list_item_get_property;
   gobject_class->set_property = gtk_list_item_set_property;
@@ -550,7 +598,5 @@ gtk_list_item_set_selectable (GtkListItem *self,
 
   self->selectable = selectable;
 
-  gtk_widget_set_can_focus (GTK_WIDGET (self), self->selectable);
-
   g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_SELECTABLE]);
 }