joinedmenu: add helper to join menus instead of nesting

In many cases, we have an "extra-menu" property that is used to allow
applications to join menus into the native menu for the widget. Previously,
this was done by nesting that menu in a section.

Doing so increases the complexity of the rules for GtkMenuTracker as you
may want different handling from inside of the section vs toplevel
sections.

If instead we synthetically glue the menus together, we have a much more
natural joining of menus as the application developer would expect for
their menu.

This also ports GtkLabel, GtkText, GtkPasswordEntry, and GtkTextView to
use the joined menu helper.

The joined menu helper comes originally from GNOME Builder and has had
extensive use there.

Fixes #4094

7 files changed, 391 insertions, 9 deletions

diff --git a/gtk/gtkjoinedmenu.c b/gtk/gtkjoinedmenu.c
new file mode 100644
index 0000000000..bd1be741b2
--- /dev/null
+++ b/gtk/gtkjoinedmenu.c
@@ -0,0 +1,315 @@
+/*
+ * Copyright © 2020 Red Hat, Inc.
+ *
+ * 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/>.
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ */
+
+#include "config.h"
+
+#include "gtkjoinedmenuprivate.h"
+
+typedef struct
+{
+  GMenuModel *model;
+  gulong      items_changed_handler;
+} Menu;
+
+struct _GtkJoinedMenu
+{
+  GMenuModel  parent_instance;
+  GArray     *menus;
+};
+
+G_DEFINE_TYPE (GtkJoinedMenu, gtk_joined_menu, G_TYPE_MENU_MODEL)
+
+static void
+clear_menu (gpointer data)
+{
+  Menu *menu = data;
+
+  g_clear_signal_handler (&menu->items_changed_handler, menu->model);
+  g_clear_object (&menu->model);
+}
+
+static gint
+gtk_joined_menu_get_offset_at_index (GtkJoinedMenu *self,
+                                     gint           index)
+{
+  gint offset = 0;
+
+  for (guint i = 0; i < index; i++)
+    offset += g_menu_model_get_n_items (g_array_index (self->menus, Menu, i).model);
+
+  return offset;
+}
+
+static gint
+gtk_joined_menu_get_offset_at_model (GtkJoinedMenu *self,
+                                     GMenuModel    *model)
+{
+  gint offset = 0;
+
+  for (guint i = 0; i < self->menus->len; i++)
+    {
+      const Menu *menu = &g_array_index (self->menus, Menu, i);
+
+      if (menu->model == model)
+        break;
+
+      offset += g_menu_model_get_n_items (menu->model);
+    }
+
+  return offset;
+}
+
+static gboolean
+gtk_joined_menu_is_mutable (GMenuModel *model)
+{
+  return TRUE;
+}
+
+static gint
+gtk_joined_menu_get_n_items (GMenuModel *model)
+{
+  GtkJoinedMenu *self = (GtkJoinedMenu *)model;
+
+  if (self->menus->len == 0)
+    return 0;
+
+  return gtk_joined_menu_get_offset_at_index (self, self->menus->len);
+}
+
+static const Menu *
+gtk_joined_menu_get_item (GtkJoinedMenu *self,
+                          gint          *item_index)
+{
+  g_assert (GTK_IS_JOINED_MENU (self));
+
+  for (guint i = 0; i < self->menus->len; i++)
+    {
+      const Menu *menu = &g_array_index (self->menus, Menu, i);
+      gint n_items = g_menu_model_get_n_items (menu->model);
+
+      if (n_items > *item_index)
+        return menu;
+
+      (*item_index) -= n_items;
+    }
+
+  g_return_val_if_reached (NULL);
+}
+
+static void
+gtk_joined_menu_get_item_attributes (GMenuModel  *model,
+                                     gint         item_index,
+                                     GHashTable **attributes)
+{
+  const Menu *menu = gtk_joined_menu_get_item (GTK_JOINED_MENU (model), &item_index);
+  G_MENU_MODEL_GET_CLASS (menu->model)->get_item_attributes (menu->model, item_index, attributes);
+}
+
+static GMenuAttributeIter *
+gtk_joined_menu_iterate_item_attributes (GMenuModel *model,
+                                         gint        item_index)
+{
+  const Menu *menu = gtk_joined_menu_get_item (GTK_JOINED_MENU (model), &item_index);
+  return G_MENU_MODEL_GET_CLASS (menu->model)->iterate_item_attributes (menu->model, item_index);
+}
+
+static GVariant *
+gtk_joined_menu_get_item_attribute_value (GMenuModel         *model,
+                                          gint                item_index,
+                                          const gchar        *attribute,
+                                          const GVariantType *expected_type)
+{
+  const Menu *menu = gtk_joined_menu_get_item (GTK_JOINED_MENU (model), &item_index);
+  return G_MENU_MODEL_GET_CLASS (menu->model)->get_item_attribute_value (menu->model, item_index, attribute, expected_type);
+}
+
+static void
+gtk_joined_menu_get_item_links (GMenuModel  *model,
+                                gint         item_index,
+                                GHashTable **links)
+{
+  const Menu *menu = gtk_joined_menu_get_item (GTK_JOINED_MENU (model), &item_index);
+  G_MENU_MODEL_GET_CLASS (menu->model)->get_item_links (menu->model, item_index, links);
+}
+
+static GMenuLinkIter *
+gtk_joined_menu_iterate_item_links (GMenuModel *model,
+                                    gint        item_index)
+{
+  const Menu *menu = gtk_joined_menu_get_item (GTK_JOINED_MENU (model), &item_index);
+  return G_MENU_MODEL_GET_CLASS (menu->model)->iterate_item_links (menu->model, item_index);
+}
+
+static GMenuModel *
+gtk_joined_menu_get_item_link (GMenuModel  *model,
+                               gint         item_index,
+                               const gchar *link)
+{
+  const Menu *menu = gtk_joined_menu_get_item (GTK_JOINED_MENU (model), &item_index);
+  return G_MENU_MODEL_GET_CLASS (menu->model)->get_item_link (menu->model, item_index, link);
+}
+
+static void
+gtk_joined_menu_finalize (GObject *object)
+{
+  GtkJoinedMenu *self = (GtkJoinedMenu *)object;
+
+  g_clear_pointer (&self->menus, g_array_unref);
+
+  G_OBJECT_CLASS (gtk_joined_menu_parent_class)->finalize (object);
+}
+
+static void
+gtk_joined_menu_class_init (GtkJoinedMenuClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+  GMenuModelClass *menu_model_class = G_MENU_MODEL_CLASS (klass);
+
+  object_class->finalize = gtk_joined_menu_finalize;
+
+  menu_model_class->is_mutable = gtk_joined_menu_is_mutable;
+  menu_model_class->get_n_items = gtk_joined_menu_get_n_items;
+  menu_model_class->get_item_attributes = gtk_joined_menu_get_item_attributes;
+  menu_model_class->iterate_item_attributes = gtk_joined_menu_iterate_item_attributes;
+  menu_model_class->get_item_attribute_value = gtk_joined_menu_get_item_attribute_value;
+  menu_model_class->get_item_links = gtk_joined_menu_get_item_links;
+  menu_model_class->iterate_item_links = gtk_joined_menu_iterate_item_links;
+  menu_model_class->get_item_link = gtk_joined_menu_get_item_link;
+}
+
+static void
+gtk_joined_menu_init (GtkJoinedMenu *self)
+{
+  self->menus = g_array_new (FALSE, FALSE, sizeof (Menu));
+  g_array_set_clear_func (self->menus, clear_menu);
+}
+
+static void
+gtk_joined_menu_on_items_changed (GtkJoinedMenu *self,
+                                  guint          offset,
+                                  guint          removed,
+                                  guint          added,
+                                  GMenuModel    *model)
+{
+  g_assert (GTK_IS_JOINED_MENU (self));
+  g_assert (G_IS_MENU_MODEL (model));
+
+  offset += gtk_joined_menu_get_offset_at_model (self, model);
+  g_menu_model_items_changed (G_MENU_MODEL (self), offset, removed, added);
+}
+
+GtkJoinedMenu *
+gtk_joined_menu_new (void)
+{
+  return g_object_new (GTK_TYPE_JOINED_MENU, NULL);
+}
+
+static void
+gtk_joined_menu_insert (GtkJoinedMenu *self,
+                        GMenuModel    *model,
+                        gint           index)
+{
+  Menu menu = { 0 };
+  gint offset;
+  gint n_items;
+
+  g_assert (GTK_IS_JOINED_MENU (self));
+  g_assert (G_IS_MENU_MODEL (model));
+  g_assert (index >= 0);
+  g_assert (index <= self->menus->len);
+
+  menu.model = g_object_ref (model);
+  menu.items_changed_handler =
+    g_signal_connect_swapped (menu.model,
+                              "items-changed",
+                              G_CALLBACK (gtk_joined_menu_on_items_changed),
+                              self);
+  g_array_insert_val (self->menus, index, menu);
+
+  n_items = g_menu_model_get_n_items (model);
+  offset = gtk_joined_menu_get_offset_at_index (self, index);
+  g_menu_model_items_changed (G_MENU_MODEL (self), offset, 0, n_items);
+}
+
+void
+gtk_joined_menu_append_menu (GtkJoinedMenu *self,
+                             GMenuModel    *model)
+{
+
+  g_return_if_fail (GTK_IS_JOINED_MENU (self));
+  g_return_if_fail (G_MENU_MODEL (model));
+
+  gtk_joined_menu_insert (self, model, self->menus->len);
+}
+
+void
+gtk_joined_menu_prepend_menu (GtkJoinedMenu *self,
+                              GMenuModel    *model)
+{
+  g_return_if_fail (GTK_IS_JOINED_MENU (self));
+  g_return_if_fail (G_MENU_MODEL (model));
+
+  gtk_joined_menu_insert (self, model, 0);
+}
+
+void
+gtk_joined_menu_remove_index (GtkJoinedMenu *self,
+                              guint          index)
+{
+  const Menu *menu;
+  gint n_items;
+  gint offset;
+
+  g_return_if_fail (GTK_IS_JOINED_MENU (self));
+  g_return_if_fail (index < self->menus->len);
+
+  menu = &g_array_index (self->menus, Menu, index);
+
+  offset = gtk_joined_menu_get_offset_at_index (self, index);
+  n_items = g_menu_model_get_n_items (menu->model);
+
+  g_array_remove_index (self->menus, index);
+
+  g_menu_model_items_changed (G_MENU_MODEL (self), offset, n_items, 0);
+}
+
+void
+gtk_joined_menu_remove_menu (GtkJoinedMenu *self,
+                             GMenuModel    *model)
+{
+  g_return_if_fail (GTK_IS_JOINED_MENU (self));
+  g_return_if_fail (G_IS_MENU_MODEL (model));
+
+  for (guint i = 0; i < self->menus->len; i++)
+    {
+      if (g_array_index (self->menus, Menu, i).model == model)
+        {
+          gtk_joined_menu_remove_index (self, i);
+          break;
+        }
+    }
+}
+
+guint
+gtk_joined_menu_get_n_joined (GtkJoinedMenu *self)
+{
+  g_return_val_if_fail (GTK_IS_JOINED_MENU (self), 0);
+
+  return self->menus->len;
+}
diff --git a/gtk/gtkjoinedmenuprivate.h b/gtk/gtkjoinedmenuprivate.h
new file mode 100644
index 0000000000..8e4b61e6cb
--- /dev/null
+++ b/gtk/gtkjoinedmenuprivate.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright © 2020 Red Hat, Inc.
+ *
+ * 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/>.
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ */
+
+#pragma once
+
+#include <gio/gio.h>
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_JOINED_MENU (gtk_joined_menu_get_type())
+
+G_DECLARE_FINAL_TYPE (GtkJoinedMenu, gtk_joined_menu, GTK, JOINED_MENU, GMenuModel)
+
+GtkJoinedMenu *gtk_joined_menu_new          (void);
+guint          gtk_joined_menu_get_n_joined (GtkJoinedMenu *self);
+void           gtk_joined_menu_append_menu  (GtkJoinedMenu *self,
+                                             GMenuModel    *model);
+void           gtk_joined_menu_prepend_menu (GtkJoinedMenu *self,
+                                             GMenuModel    *model);
+void           gtk_joined_menu_remove_menu  (GtkJoinedMenu *self,
+                                             GMenuModel    *model);
+void           gtk_joined_menu_remove_index (GtkJoinedMenu *self,
+                                             guint          index);
+
+G_END_DECLS
diff --git a/gtk/gtklabel.c b/gtk/gtklabel.c
index bfa231b9d9..ced834f980 100644
--- a/gtk/gtklabel.c
+++ b/gtk/gtklabel.c
@@ -52,6 +52,7 @@
 #include "gtkdragsourceprivate.h"
 #include "gtkdragicon.h"
 #include "gtkcsscolorvalueprivate.h"
+#include "gtkjoinedmenuprivate.h"
 
 #include <math.h>
 #include <string.h>
@@ -5468,9 +5469,11 @@ gtk_label_move_cursor (GtkLabel       *self,
 static GMenuModel *
 gtk_label_get_menu_model (GtkLabel *self)
 {
+  GtkJoinedMenu *joined;
   GMenu *menu, *section;
   GMenuItem *item;
 
+  joined = gtk_joined_menu_new ();
   menu = g_menu_new ();
 
   section = g_menu_new ();
@@ -5498,10 +5501,13 @@ gtk_label_get_menu_model (GtkLabel *self)
   g_menu_append_section (menu, NULL, G_MENU_MODEL (section));
   g_object_unref (section);
 
+  gtk_joined_menu_append_menu (joined, G_MENU_MODEL (menu));
+  g_object_unref (menu);
+
   if (self->extra_menu)
-    g_menu_append_section (menu, NULL, self->extra_menu);
+    gtk_joined_menu_append_menu (joined, self->extra_menu);
 
-  return G_MENU_MODEL (menu);
+  return G_MENU_MODEL (joined);
 }
 
 static void
diff --git a/gtk/gtkpasswordentry.c b/gtk/gtkpasswordentry.c
index 7e6e470dd7..4975ee7312 100644
--- a/gtk/gtkpasswordentry.c
+++ b/gtk/gtkpasswordentry.c
@@ -36,6 +36,7 @@
 #include "gtkwidgetprivate.h"
 #include "gtkcsspositionvalueprivate.h"
 #include "gtkcssnodeprivate.h"
+#include "gtkjoinedmenuprivate.h"
 
 
 /**
@@ -658,6 +659,7 @@ void
 gtk_password_entry_set_extra_menu (GtkPasswordEntry *entry,
                                    GMenuModel       *model)
 {
+  GtkJoinedMenu *joined;
   GMenu *menu;
   GMenu *section;
   GMenuItem *item;
@@ -671,6 +673,7 @@ gtk_password_entry_set_extra_menu (GtkPasswordEntry *entry,
         return;
     }
 
+  joined = gtk_joined_menu_new ();
   menu = g_menu_new ();
 
   section = g_menu_new ();
@@ -682,12 +685,15 @@ gtk_password_entry_set_extra_menu (GtkPasswordEntry *entry,
   g_menu_append_section (menu, NULL, G_MENU_MODEL (section));
   g_object_unref (section);
 
+  gtk_joined_menu_append_menu (joined, G_MENU_MODEL (menu));
+  g_object_unref (menu);
+
   if (model)
-    g_menu_append_section (menu, NULL, model);
+    gtk_joined_menu_append_menu (joined, model);
 
-  gtk_text_set_extra_menu (GTK_TEXT (entry->entry), G_MENU_MODEL (menu));
+  gtk_text_set_extra_menu (GTK_TEXT (entry->entry), G_MENU_MODEL (joined));
 
-  g_object_unref (menu);
+  g_object_unref (joined);
 
   g_object_notify_by_pspec (G_OBJECT (entry), props[PROP_EXTRA_MENU]);
 }
diff --git a/gtk/gtktext.c b/gtk/gtktext.c
index 8e7fbf3cc1..8d1bde4674 100644
--- a/gtk/gtktext.c
+++ b/gtk/gtktext.c
@@ -64,6 +64,7 @@
 #include "gtkwindow.h"
 #include "gtknative.h"
 #include "gtkactionmuxerprivate.h"
+#include "gtkjoinedmenuprivate.h"
 
 #include <cairo-gobject.h>
 #include <string.h>
@@ -6035,9 +6036,11 @@ static GMenuModel *
 gtk_text_get_menu_model (GtkText *self)
 {
   GtkTextPrivate *priv = gtk_text_get_instance_private (self);
+  GtkJoinedMenu *joined;
   GMenu *menu, *section;
   GMenuItem *item;
 
+  joined = gtk_joined_menu_new ();
   menu = g_menu_new ();
 
   section = g_menu_new ();
@@ -6075,10 +6078,13 @@ gtk_text_get_menu_model (GtkText *self)
   g_menu_append_section (menu, NULL, G_MENU_MODEL (section));
   g_object_unref (section);
 
+  gtk_joined_menu_append_menu (joined, G_MENU_MODEL (menu));
+  g_object_unref (menu);
+
   if (priv->extra_menu)
-    g_menu_append_section (menu, NULL, priv->extra_menu);
+    gtk_joined_menu_append_menu (joined, priv->extra_menu);
 
-  return G_MENU_MODEL (menu);
+  return G_MENU_MODEL (joined);
 }
 
 static gboolean
diff --git a/gtk/gtktextview.c b/gtk/gtktextview.c
index 5bf134302c..4796a34b1e 100644
--- a/gtk/gtktextview.c
+++ b/gtk/gtktextview.c
@@ -56,6 +56,7 @@
 #include "gtkpango.h"
 #include "gtknative.h"
 #include "gtkwidgetprivate.h"
+#include "gtkjoinedmenuprivate.h"
 
 /**
  * GtkTextView:
@@ -8733,9 +8734,12 @@ static GMenuModel *
 gtk_text_view_get_menu_model (GtkTextView *text_view)
 {
   GtkTextViewPrivate *priv = text_view->priv;
+  GtkJoinedMenu *joined;
   GMenu *menu, *section;
   GMenuItem *item;
 
+  joined = gtk_joined_menu_new ();
+
   menu = g_menu_new ();
 
   section = g_menu_new ();
@@ -8785,10 +8789,13 @@ gtk_text_view_get_menu_model (GtkTextView *text_view)
   g_menu_append_section (menu, NULL, G_MENU_MODEL (section));
   g_object_unref (section);
 
+  gtk_joined_menu_append_menu (joined, G_MENU_MODEL (menu));
+  g_object_unref (menu);
+
   if (priv->extra_menu)
-    g_menu_append_section (menu, NULL, priv->extra_menu);
+    gtk_joined_menu_append_menu (joined, priv->extra_menu);
 
-  return G_MENU_MODEL (menu);
+  return G_MENU_MODEL (joined);
 }
 
 static void
diff --git a/gtk/meson.build b/gtk/meson.build
index 9e2e04d798..47ca9804a9 100644
--- a/gtk/meson.build
+++ b/gtk/meson.build
@@ -114,6 +114,7 @@ gtk_private_sources = files([
   'gtkiconcache.c',
   'gtkiconcachevalidator.c',
   'gtkiconhelper.c',
+  'gtkjoinedmenu.c',
   'gtkkineticscrolling.c',
   'gtkmagnifier.c',
   'gtkmenusectionbox.c',