[gnome-builder/wip/gtk4-port] libide/gtk: add helper to hide widget when model is empty

[Christian Hergert <chergert src gnome org>]

commit 52f1d02a3ff68de7e73d32eb939f6a78c0e55e23
Author: Christian Hergert <chergert redhat com>
Date:   Sat Jun 11 00:50:25 2022 -0700

    libide/gtk: add helper to hide widget when model is empty

 src/libide/gtk/ide-gtk.c | 29 +++++++++++++++++++++++++++++
 src/libide/gtk/ide-gtk.h |  3 +++
 2 files changed, 32 insertions(+)
---
diff --git a/src/libide/gtk/ide-gtk.c b/src/libide/gtk/ide-gtk.c
index 8649ef1d5..56e2f295f 100644
--- a/src/libide/gtk/ide-gtk.c
+++ b/src/libide/gtk/ide-gtk.c
@@ -532,3 +532,32 @@ ide_gtk_list_view_get_selected_row (GtkListView *view,
   *position = gtk_bitset_get_minimum (bitset);
   return TRUE;
 }
+
+static void
+on_items_changed_cb (GListModel *model,
+                     guint       position,
+                     guint       removed,
+                     guint       added,
+                     GtkWidget  *widget)
+{
+  gboolean was_visible = gtk_widget_get_visible (widget);
+  gboolean is_visible = added > 0 || g_list_model_get_n_items (model) > 0;
+
+  if (was_visible != is_visible)
+    gtk_widget_set_visible (widget, is_visible);
+}
+
+void
+ide_gtk_widget_hide_when_empty (GtkWidget  *widget,
+                                GListModel *model)
+{
+  g_return_if_fail (GTK_IS_WIDGET (widget));
+  g_return_if_fail (G_IS_LIST_MODEL (model));
+
+  gtk_widget_set_visible (widget, g_list_model_get_n_items (model) > 0);
+  g_signal_connect_object (model,
+                           "items-changed",
+                           G_CALLBACK (on_items_changed_cb),
+                           widget,
+                           0);
+}
diff --git a/src/libide/gtk/ide-gtk.h b/src/libide/gtk/ide-gtk.h
index f06a5b0f2..6aa5bfae0 100644
--- a/src/libide/gtk/ide-gtk.h
+++ b/src/libide/gtk/ide-gtk.h
@@ -66,5 +66,8 @@ void       ide_gtk_list_view_move_previous    (GtkListView       *view);
 IDE_AVAILABLE_IN_ALL
 gboolean   ide_gtk_list_view_get_selected_row (GtkListView       *view,
                                                guint             *position);
+IDE_AVAILABLE_IN_ALL
+void       ide_gtk_widget_hide_when_empty     (GtkWidget         *widget,
+                                               GListModel        *model);
 
 G_END_DECLS