/* GTK - The GIMP Toolkit

 * Copyright (C) 2000 Red Hat, Inc.

 * Copyright (C) 2004 Nokia Corporation

 * Copyright (C) 2006-2008 Imendio AB

 *

 * 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 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, write to the

 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,

 * Boston, MA 02111-1307, USA.

 *

 */

#include "config.h"

#include <string.h>

#import <Cocoa/Cocoa.h>

#include "gtkclipboard.h"

#include "gtkinvisible.h"

#include "gtkmain.h"

#include "gtkmarshalers.h"

#include "gtkintl.h"

#include "gtktextbuffer.h"

#include "gtkquartz.h"

#include "gtkalias.h"

enum {

  OWNER_CHANGE,

  LAST_SIGNAL

};

@interface GtkClipboardOwner : NSObject {

  GtkClipboard *clipboard;

  @public

  gboolean setting_same_owner;

}

@end

typedef struct _GtkClipboardClass GtkClipboardClass;

struct _GtkClipboard

{

  GObject parent_instance;

  NSPasteboard *pasteboard;

  GtkClipboardOwner *owner;

  NSInteger change_count;

  GdkAtom selection;

  GtkClipboardGetFunc get_func;

  GtkClipboardClearFunc clear_func;

  gpointer user_data;

  gboolean have_owner;

  GtkTargetList *target_list;

  gboolean have_selection;

  GdkDisplay *display;

  GdkAtom *cached_targets;

  gint     n_cached_targets;

  guint      notify_signal_id;

  gboolean   storing_selection;

  GMainLoop *store_loop;

  guint      store_timeout;

  gint       n_storable_targets;

  GdkAtom   *storable_targets;

};

struct _GtkClipboardClass

{

  GObjectClass parent_class;

  void (*owner_change) (GtkClipboard        *clipboard,

			GdkEventOwnerChange *event);

};

static void gtk_clipboard_class_init   (GtkClipboardClass   *class);

static void gtk_clipboard_finalize     (GObject             *object);

static void gtk_clipboard_owner_change (GtkClipboard        *clipboard,

					GdkEventOwnerChange *event);

static void          clipboard_unset      (GtkClipboard     *clipboard);

static GtkClipboard *clipboard_peek       (GdkDisplay       *display,

					   GdkAtom           selection,

					   gboolean          only_if_exists);

@implementation GtkClipboardOwner

-(void)pasteboard:(NSPasteboard *)sender provideDataForType:(NSString *)type

{

  GtkSelectionData selection_data;

  guint info;

  if (!clipboard->target_list)

    return;

  memset (&selection_data, 0, sizeof (GtkSelectionData));

  selection_data.selection = clipboard->selection;

  selection_data.target = gdk_quartz_pasteboard_type_to_atom_libgtk_only (type);

  selection_data.display = gdk_display_get_default ();

  selection_data.length = -1;

  if (gtk_target_list_find (clipboard->target_list, selection_data.target, &info))

    {

      clipboard->get_func (clipboard, &selection_data,

                           info,

                           clipboard->user_data);

      if (selection_data.length >= 0)

        _gtk_quartz_set_selection_data_for_pasteboard (clipboard->pasteboard,

                                                       &selection_data);

      g_free (selection_data.data);

    }

}

/*  pasteboardChangedOwner is not called immediately, and it's not called

 *  reliably. It is somehow documented in the apple api docs, but the docs

 *  suck and don't really give clear instructions. Therefore we track

 *  changeCount in several places below and clear the clipboard if it

 *  changed.

 */

- (void)pasteboardChangedOwner:(NSPasteboard *)sender

{

  if (! setting_same_owner)

    clipboard_unset (clipboard);

}

- (id)initWithClipboard:(GtkClipboard *)aClipboard

{

  self = [super init];

  if (self)

    {

      clipboard = aClipboard;

      setting_same_owner = FALSE;

    }

  return self;

}

@end

static const gchar clipboards_owned_key[] = "gtk-clipboards-owned";

static GQuark clipboards_owned_key_id = 0;

static GObjectClass *parent_class;

static guint         clipboard_signals[LAST_SIGNAL] = { 0 };

GType

gtk_clipboard_get_type (void)

{

  static GType clipboard_type = 0;

  if (!clipboard_type)

    {

      const GTypeInfo clipboard_info =

      {

	sizeof (GtkClipboardClass),

	NULL,           /* base_init */

	NULL,           /* base_finalize */

	(GClassInitFunc) gtk_clipboard_class_init,

	NULL,           /* class_finalize */

	NULL,           /* class_data */

	sizeof (GtkClipboard),

	0,              /* n_preallocs */

	(GInstanceInitFunc) NULL,

      };

      clipboard_type = g_type_register_static (G_TYPE_OBJECT, I_("GtkClipboard"),

					       &clipboard_info, 0);

    }

  return clipboard_type;

}

static void

gtk_clipboard_class_init (GtkClipboardClass *class)

{

  GObjectClass *gobject_class = G_OBJECT_CLASS (class);

  parent_class = g_type_class_peek_parent (class);

  gobject_class->finalize = gtk_clipboard_finalize;

  class->owner_change = gtk_clipboard_owner_change;

  clipboard_signals[OWNER_CHANGE] =

    g_signal_new (I_("owner-change"),

		  G_TYPE_FROM_CLASS (gobject_class),

		  G_SIGNAL_RUN_FIRST,

		  G_STRUCT_OFFSET (GtkClipboardClass, owner_change),

		  NULL, NULL,

		  _gtk_marshal_VOID__BOXED,

		  G_TYPE_NONE, 1,

		  GDK_TYPE_EVENT | G_SIGNAL_TYPE_STATIC_SCOPE);

}

static void

gtk_clipboard_finalize (GObject *object)

{

  GtkClipboard *clipboard;

  GSList *clipboards;

  clipboard = GTK_CLIPBOARD (object);

  clipboards = g_object_get_data (G_OBJECT (clipboard->display), "gtk-clipboard-list");

  if (g_slist_index (clipboards, clipboard) >= 0)

    g_warning ("GtkClipboard prematurely finalized");

  clipboard_unset (clipboard);

  clipboards = g_object_get_data (G_OBJECT (clipboard->display), "gtk-clipboard-list");

  clipboards = g_slist_remove (clipboards, clipboard);

  g_object_set_data (G_OBJECT (clipboard->display), I_("gtk-clipboard-list"), clipboards);

  if (clipboard->store_loop && g_main_loop_is_running (clipboard->store_loop))

    g_main_loop_quit (clipboard->store_loop);

  if (clipboard->store_timeout != 0)

    g_source_remove (clipboard->store_timeout);

  g_free (clipboard->storable_targets);

  G_OBJECT_CLASS (parent_class)->finalize (object);

}

static void

clipboard_display_closed (GdkDisplay   *display,

			  gboolean      is_error,

			  GtkClipboard *clipboard)

{

  GSList *clipboards;

  clipboards = g_object_get_data (G_OBJECT (display), "gtk-clipboard-list");

  g_object_run_dispose (G_OBJECT (clipboard));

  clipboards = g_slist_remove (clipboards, clipboard);

  g_object_set_data (G_OBJECT (display), I_("gtk-clipboard-list"), clipboards);

  g_object_unref (clipboard);

}

GtkClipboard *

gtk_clipboard_get_for_display (GdkDisplay *display,

			       GdkAtom     selection)

{

  g_return_val_if_fail (GDK_IS_DISPLAY (display), NULL);

  g_return_val_if_fail (!display->closed, NULL);

  return clipboard_peek (display, selection, FALSE);

}

GtkClipboard *

gtk_clipboard_get (GdkAtom selection)

{

  return gtk_clipboard_get_for_display (gdk_display_get_default (), selection);

}

static void

clipboard_owner_destroyed (gpointer data)

{

  GSList *clipboards = data;

  GSList *tmp_list;

  tmp_list = clipboards;

  while (tmp_list)

    {

      GtkClipboard *clipboard = tmp_list->data;

      clipboard->get_func = NULL;

      clipboard->clear_func = NULL;

      clipboard->user_data = NULL;

      clipboard->have_owner = FALSE;

      if (clipboard->target_list)

        {

          gtk_target_list_unref (clipboard->target_list);

          clipboard->target_list = NULL;

        }

      gtk_clipboard_clear (clipboard);

      tmp_list = tmp_list->next;

    }

  g_slist_free (clipboards);

}

static void

clipboard_add_owner_notify (GtkClipboard *clipboard)

{

  if (!clipboards_owned_key_id)

    clipboards_owned_key_id = g_quark_from_static_string (clipboards_owned_key);

  if (clipboard->have_owner)

    g_object_set_qdata_full (clipboard->user_data, clipboards_owned_key_id,

			     g_slist_prepend (g_object_steal_qdata (clipboard->user_data,

								    clipboards_owned_key_id),

					      clipboard),

			     clipboard_owner_destroyed);

}

static void

clipboard_remove_owner_notify (GtkClipboard *clipboard)

{

  if (clipboard->have_owner)

     g_object_set_qdata_full (clipboard->user_data, clipboards_owned_key_id,

			      g_slist_remove (g_object_steal_qdata (clipboard->user_data,

								    clipboards_owned_key_id),

					      clipboard),

			      clipboard_owner_destroyed);

}

static gboolean

gtk_clipboard_set_contents (GtkClipboard         *clipboard,

			    const GtkTargetEntry *targets,

			    guint                 n_targets,

			    GtkClipboardGetFunc   get_func,

			    GtkClipboardClearFunc clear_func,

			    gpointer              user_data,

			    gboolean              have_owner)

{

  GtkClipboardOwner *owner;

  NSSet *types;

  NSAutoreleasePool *pool;

  if (!(clipboard->have_owner && have_owner) ||

      clipboard->user_data != user_data)

    {

      clipboard_unset (clipboard);

      if (clipboard->get_func)

        {

          /* Calling unset() caused the clipboard contents to be reset!

           * Avoid leaking and return

           */

          if (!(clipboard->have_owner && have_owner) ||

              clipboard->user_data != user_data)

            {

              (*clear_func) (clipboard, user_data);

              return FALSE;

            }

          else

            {

              return TRUE;

            }

        }

    }

  pool = [[NSAutoreleasePool alloc] init];

  types = _gtk_quartz_target_entries_to_pasteboard_types (targets, n_targets);

  /*  call declareTypes before setting the clipboard members because

   *  declareTypes might clear the clipboard

   */

  if (user_data && user_data == clipboard->user_data)

    {

      owner = [clipboard->owner retain];

      owner->setting_same_owner = TRUE;

      clipboard->change_count = [clipboard->pasteboard declareTypes: [types allObjects]

                                                              owner: owner];

      owner->setting_same_owner = FALSE;

    }

  else

    {

      owner = [[GtkClipboardOwner alloc] initWithClipboard:clipboard];

      clipboard->change_count = [clipboard->pasteboard declareTypes: [types allObjects]

                                                              owner: owner];

    }

  [owner release];

  [types release];

  [pool release];

  clipboard->owner = owner;

  clipboard->user_data = user_data;

  clipboard->have_owner = have_owner;

  if (have_owner)

    clipboard_add_owner_notify (clipboard);

  clipboard->get_func = get_func;

  clipboard->clear_func = clear_func;

  if (clipboard->target_list)

    gtk_target_list_unref (clipboard->target_list);

  clipboard->target_list = gtk_target_list_new (targets, n_targets);

  return TRUE;

}

gboolean

gtk_clipboard_set_with_data (GtkClipboard          *clipboard,

			     const GtkTargetEntry  *targets,

			     guint                  n_targets,

			     GtkClipboardGetFunc    get_func,

			     GtkClipboardClearFunc  clear_func,

			     gpointer               user_data)

{

  g_return_val_if_fail (clipboard != NULL, FALSE);

  g_return_val_if_fail (targets != NULL, FALSE);

  g_return_val_if_fail (get_func != NULL, FALSE);

  return gtk_clipboard_set_contents (clipboard, targets, n_targets,

				     get_func, clear_func, user_data,

				     FALSE);

}

gboolean

gtk_clipboard_set_with_owner (GtkClipboard          *clipboard,

			      const GtkTargetEntry  *targets,

			      guint                  n_targets,

			      GtkClipboardGetFunc    get_func,

			      GtkClipboardClearFunc  clear_func,

			      GObject               *owner)

{

  g_return_val_if_fail (clipboard != NULL, FALSE);

  g_return_val_if_fail (targets != NULL, FALSE);

  g_return_val_if_fail (get_func != NULL, FALSE);

  g_return_val_if_fail (G_IS_OBJECT (owner), FALSE);

  return gtk_clipboard_set_contents (clipboard, targets, n_targets,

				     get_func, clear_func, owner,

				     TRUE);

}

GObject *

gtk_clipboard_get_owner (GtkClipboard *clipboard)

{

  g_return_val_if_fail (clipboard != NULL, NULL);

  if (clipboard->change_count < [clipboard->pasteboard changeCount])

    {

      clipboard_unset (clipboard);

      clipboard->change_count = [clipboard->pasteboard changeCount];

    }

  if (clipboard->have_owner)

    return clipboard->user_data;

  else

    return NULL;

}

static void

clipboard_unset (GtkClipboard *clipboard)

{

  GtkClipboardClearFunc old_clear_func;

  gpointer old_data;

  gboolean old_have_owner;

  gint old_n_storable_targets;

  old_clear_func = clipboard->clear_func;

  old_data = clipboard->user_data;

  old_have_owner = clipboard->have_owner;

  old_n_storable_targets = clipboard->n_storable_targets;

  if (old_have_owner)

    {

      clipboard_remove_owner_notify (clipboard);

      clipboard->have_owner = FALSE;

    }

  clipboard->n_storable_targets = -1;

  g_free (clipboard->storable_targets);

  clipboard->storable_targets = NULL;

  clipboard->owner = NULL;

  clipboard->get_func = NULL;

  clipboard->clear_func = NULL;

  clipboard->user_data = NULL;

  if (old_clear_func)

    old_clear_func (clipboard, old_data);

  if (clipboard->target_list)

    {

      gtk_target_list_unref (clipboard->target_list);

      clipboard->target_list = NULL;

    }

  /* If we've transferred the clipboard data to the manager,

   * unref the owner

   */

  if (old_have_owner &&

      old_n_storable_targets != -1)

    g_object_unref (old_data);

}

void

gtk_clipboard_clear (GtkClipboard *clipboard)

{

  clipboard_unset (clipboard);

  [clipboard->pasteboard declareTypes:nil owner:nil];

}

static void

text_get_func (GtkClipboard     *clipboard,

	       GtkSelectionData *selection_data,

	       guint             info,

	       gpointer          data)

{

  gtk_selection_data_set_text (selection_data, data, -1);

}

static void

text_clear_func (GtkClipboard *clipboard,

		 gpointer      data)

{

  g_free (data);

}

void

gtk_clipboard_set_text (GtkClipboard *clipboard,

			const gchar  *text,

			gint          len)

{

  GtkTargetEntry target = { "UTF8_STRING", 0, 0 };

  g_return_if_fail (clipboard != NULL);

  g_return_if_fail (text != NULL);

  if (len < 0)

    len = strlen (text);

  gtk_clipboard_set_with_data (clipboard,

			       &target, 1,

			       text_get_func, text_clear_func,

			       g_strndup (text, len));

  gtk_clipboard_set_can_store (clipboard, NULL, 0);

}

static void

pixbuf_get_func (GtkClipboard     *clipboard,

		 GtkSelectionData *selection_data,

		 guint             info,

		 gpointer          data)

{

  gtk_selection_data_set_pixbuf (selection_data, data);

}

static void

pixbuf_clear_func (GtkClipboard *clipboard,

		   gpointer      data)

{

  g_object_unref (data);

}

void

gtk_clipboard_set_image (GtkClipboard *clipboard,

			 GdkPixbuf    *pixbuf)

{

  GtkTargetList *list;

  GList *l;

  GtkTargetEntry *targets;

  gint n_targets, i;

  g_return_if_fail (clipboard != NULL);

  g_return_if_fail (GDK_IS_PIXBUF (pixbuf));

  list = gtk_target_list_new (NULL, 0);

  gtk_target_list_add_image_targets (list, 0, TRUE);

  n_targets = g_list_length (list->list);

  targets = g_new0 (GtkTargetEntry, n_targets);

  for (l = list->list, i = 0; l; l = l->next, i++)

    {

      GtkTargetPair *pair = (GtkTargetPair *)l->data;

      targets[i].target = gdk_atom_name (pair->target);

    }

  gtk_clipboard_set_with_data (clipboard,

			       targets, n_targets,

			       pixbuf_get_func, pixbuf_clear_func,

			       g_object_ref (pixbuf));

  gtk_clipboard_set_can_store (clipboard, NULL, 0);

  for (i = 0; i < n_targets; i++)

    g_free (targets[i].target);

  g_free (targets);

  gtk_target_list_unref (list);

}

void

gtk_clipboard_request_contents (GtkClipboard            *clipboard,

				GdkAtom                  target,

				GtkClipboardReceivedFunc callback,

				gpointer                 user_data)

{

  GtkSelectionData *data;

  data = gtk_clipboard_wait_for_contents (clipboard, target);

  callback (clipboard, data, user_data);

  gtk_selection_data_free (data);

}

void

gtk_clipboard_request_text (GtkClipboard                *clipboard,

			    GtkClipboardTextReceivedFunc callback,

			    gpointer                     user_data)

{

  gchar *data = gtk_clipboard_wait_for_text (clipboard);

  callback (clipboard, data, user_data);

  g_free (data);

}

void

gtk_clipboard_request_rich_text (GtkClipboard                    *clipboard,

                                 GtkTextBuffer                   *buffer,

                                 GtkClipboardRichTextReceivedFunc callback,

                                 gpointer                         user_data)

{

  /* FIXME: Implement */

}

guint8 *

gtk_clipboard_wait_for_rich_text (GtkClipboard  *clipboard,

                                  GtkTextBuffer *buffer,

                                  GdkAtom       *format,

                                  gsize         *length)

{

  /* FIXME: Implement */

  return NULL;

}

void

gtk_clipboard_request_image (GtkClipboard                  *clipboard,

			     GtkClipboardImageReceivedFunc  callback,

			     gpointer                       user_data)

{

  GdkPixbuf *pixbuf = gtk_clipboard_wait_for_image (clipboard);

  callback (clipboard, pixbuf, user_data);

  if (pixbuf)

    g_object_unref (pixbuf);

}

void

gtk_clipboard_request_uris (GtkClipboard                *clipboard,

			    GtkClipboardURIReceivedFunc  callback,

			    gpointer                     user_data)

{

  gchar **uris = gtk_clipboard_wait_for_uris (clipboard);

  callback (clipboard, uris, user_data);

  g_strfreev (uris);

}

void

gtk_clipboard_request_targets (GtkClipboard                *clipboard,

			       GtkClipboardTargetsReceivedFunc callback,

			       gpointer                     user_data)

{

  GdkAtom *targets;

  gint n_targets;

  gtk_clipboard_wait_for_targets (clipboard, &targets, &n_targets);

  callback (clipboard, targets, n_targets, user_data);

}

GtkSelectionData *

gtk_clipboard_wait_for_contents (GtkClipboard *clipboard,

				 GdkAtom       target)

{

  NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

  GtkSelectionData *selection_data = NULL;

  if (clipboard->change_count < [clipboard->pasteboard changeCount])

    {

      clipboard_unset (clipboard);

      clipboard->change_count = [clipboard->pasteboard changeCount];

    }

  if (target == gdk_atom_intern_static_string ("TARGETS"))

    {

      NSArray *types = [clipboard->pasteboard types];

      int i, length;

      GList *atom_list, *l;

      GdkAtom *atoms;

      length = [types count] * sizeof (GdkAtom);

      selection_data = g_slice_new0 (GtkSelectionData);

      selection_data->selection = clipboard->selection;

      selection_data->target = target;

      if (!selection_data->display)

	selection_data->display = gdk_display_get_default ();

      atoms = g_malloc (length);

      atom_list = _gtk_quartz_pasteboard_types_to_atom_list (types);

      for (l = atom_list, i = 0; l ; l = l->next, i++)

	atoms[i] = GDK_POINTER_TO_ATOM (l->data);

      g_list_free (atom_list);

      gtk_selection_data_set (selection_data,

                              GDK_SELECTION_TYPE_ATOM, 32,

                              (guchar *)atoms, length);

      [pool release];

      return selection_data;

    }

  selection_data = _gtk_quartz_get_selection_data_from_pasteboard (clipboard->pasteboard,

								   target,

								   clipboard->selection);

  [pool release];

  return selection_data;

}

gchar *

gtk_clipboard_wait_for_text (GtkClipboard *clipboard)

{

  GtkSelectionData *data;

  gchar *result;

  data = gtk_clipboard_wait_for_contents (clipboard,

					  gdk_atom_intern_static_string ("UTF8_STRING"));

  result = (gchar *)gtk_selection_data_get_text (data);

  gtk_selection_data_free (data);

  return result;

}

GdkPixbuf *

gtk_clipboard_wait_for_image (GtkClipboard *clipboard)

{

  GdkAtom target = gdk_atom_intern_static_string("image/tiff");

  int i;

  GtkSelectionData *data;

  data = gtk_clipboard_wait_for_contents (clipboard, target);

  if (data && data->data)

    {

      GdkPixbuf *pixbuf = gtk_selection_data_get_pixbuf (data);

      gtk_selection_data_free (data);

      return pixbuf;

    }

  return NULL;

}

gchar **

gtk_clipboard_wait_for_uris (GtkClipboard *clipboard)

{

  GtkSelectionData *data;

  data = gtk_clipboard_wait_for_contents (clipboard, gdk_atom_intern_static_string ("text/uri-list"));

  if (data)

    {

      gchar **uris;

      uris = gtk_selection_data_get_uris (data);

      gtk_selection_data_free (data);

      return uris;

    }

  return NULL;

}

GdkDisplay *

gtk_clipboard_get_display (GtkClipboard *clipboard)

{

  g_return_val_if_fail (clipboard != NULL, NULL);

  return clipboard->display;

}

gboolean

gtk_clipboard_wait_is_text_available (GtkClipboard *clipboard)

{

  GtkSelectionData *data;

  gboolean result = FALSE;

  data = gtk_clipboard_wait_for_contents (clipboard, gdk_atom_intern_static_string ("TARGETS"));

  if (data)

    {

      result = gtk_selection_data_targets_include_text (data);

      gtk_selection_data_free (data);

    }

  return result;

}

gboolean

gtk_clipboard_wait_is_rich_text_available (GtkClipboard  *clipboard,

                                           GtkTextBuffer *buffer)

{

  GtkSelectionData *data;

  gboolean result = FALSE;

  g_return_val_if_fail (GTK_IS_CLIPBOARD (clipboard), FALSE);

  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), FALSE);

  data = gtk_clipboard_wait_for_contents (clipboard, gdk_atom_intern_static_string ("TARGETS"));

  if (data)

    {

      result = gtk_selection_data_targets_include_rich_text (data, buffer);

      gtk_selection_data_free (data);

    }

  return result;

}

gboolean

gtk_clipboard_wait_is_image_available (GtkClipboard *clipboard)

{

  GtkSelectionData *data;

  gboolean result = FALSE;

  data = gtk_clipboard_wait_for_contents (clipboard,

					  gdk_atom_intern_static_string ("TARGETS"));

  if (data)

    {

      result = gtk_selection_data_targets_include_image (data, FALSE);

      gtk_selection_data_free (data);

    }

  return result;

}

gboolean

gtk_clipboard_wait_is_uris_available (GtkClipboard *clipboard)

{

  GtkSelectionData *data;

  gboolean result = FALSE;

  data = gtk_clipboard_wait_for_contents (clipboard,

					  gdk_atom_intern_static_string ("TARGETS"));

  if (data)

    {

      result = gtk_selection_data_targets_include_uri (data);

      gtk_selection_data_free (data);

    }

  return result;

}

gboolean

gtk_clipboard_wait_for_targets (GtkClipboard  *clipboard,

				GdkAtom      **targets,

				gint          *n_targets)

{

  GtkSelectionData *data;

  gboolean result = FALSE;

  g_return_val_if_fail (clipboard != NULL, FALSE);

  /* If the display supports change notification we cache targets */