gtkfilechooser: queue visible image files for thumbnails

gtk/gtkfilechooserdefault.c

@@ -945,6 +945,75 @@ thumbnail_file_list_clear_pixbuf_caches (GtkFileChooserDefault *impl)
     gtk_widget_queue_draw (impl->browse_files_current_view);
 }
 
+static gboolean
+thumbnail_queue_should_enqueue (GtkFileChooserDefault *impl,
+                                GFile                 *file,
+                                GFileInfo             *info)
+{
+  const gchar *content_type;
+
+  if (!impl->show_thumbnails)
+    return FALSE;
+
+  if (!VIEW_MODE_USES_ICON_VIEW (impl->view_mode))
+    return FALSE;
+
+  if (file == NULL || info == NULL)
+    return FALSE;
+
+  if (g_file_info_has_attribute (info, G_FILE_ATTRIBUTE_THUMBNAIL_PATH))
+    return FALSE;
+
+  if (g_file_info_get_attribute_boolean (info, G_FILE_ATTRIBUTE_THUMBNAILING_FAILED))
+    return FALSE;
+
+  content_type = g_file_info_get_content_type (info);
+  if (content_type == NULL || !g_str_has_prefix (content_type, "image/"))
+    return FALSE;
+
+  /* Keep the first implementation conservative: only local files can be
+   * thumbnailed without surprising network or VFS latency.
+   */
+  if (!g_file_is_native (file))
+    return FALSE;
+
+  return TRUE;
+}
+
+static void
+thumbnail_queue_ensure (GtkFileChooserDefault *impl)
+{
+  if (!impl->thumbnail_cancellable)
+    impl->thumbnail_cancellable = g_cancellable_new ();
+
+  if (!impl->thumbnail_queued_files)
+    impl->thumbnail_queued_files =
+      g_hash_table_new_full ((GHashFunc) g_file_hash,
+                             (GEqualFunc) g_file_equal,
+                             g_object_unref,
+                             NULL);
+}
+
+static void
+thumbnail_queue_enqueue (GtkFileChooserDefault *impl,
+                         GFile                 *file,
+                         GFileInfo             *info)
+{
+  if (!thumbnail_queue_should_enqueue (impl, file, info))
+    return;
+
+  thumbnail_queue_ensure (impl);
+
+  if (g_hash_table_lookup (impl->thumbnail_queued_files, file))
+    return;
+
+  g_hash_table_insert (impl->thumbnail_queued_files,
+                       g_object_ref (file),
+                       GUINT_TO_POINTER (1));
+  impl->thumbnail_queue = g_slist_prepend (impl->thumbnail_queue,
+                                           g_object_ref (file));
+}
+
 static void
 gtk_file_chooser_default_finalize (GObject *object)
 {
@@ -9807,6 +9876,8 @@ file_system_model_set (GtkFileSystemModel *model,
 
           if (file_visible)
             {
+              thumbnail_queue_enqueue (impl, file, info);
+
               /* #2 start loading standard icon (callback will be handled by #1) */
               if (!g_file_info_has_attribute (info, "filechooser::icon_queried"))
                 {