[gnome-control-center] background: Add a placeholder icon before creating thumbnails

[Debarshi Ray <debarshir src gnome org>]

commit 57c83a1d59866f84d1376166ca5af34694508800
Author: Debarshi Ray <debarshir gnome org>
Date:   Thu Jan 23 14:32:48 2014 +0100

    background: Add a placeholder icon before creating thumbnails
    
    We do not wait until the first thumbnail is created to start filling up
    the store. This avoids the "No Pictures Found" message from showing up
    on slow machines were I/O and decoding the data may take a while.
    
    However, placeholders are not shown for PNGs since they might be
    screenshots.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=708943

 panels/background/bg-pictures-source.c |  116 ++++++++++++++++++++++++++++++--
 1 files changed, 109 insertions(+), 7 deletions(-)
---
diff --git a/panels/background/bg-pictures-source.c b/panels/background/bg-pictures-source.c
index b991927..9b86c87 100644
--- a/panels/background/bg-pictures-source.c
+++ b/panels/background/bg-pictures-source.c
@@ -61,6 +61,11 @@ const char * const content_types[] = {
        NULL
 };
 
+const char * const screenshot_types[] = {
+       "image/png",
+       NULL
+};
+
 static char *bg_pictures_source_get_unique_filename (const char *uri);
 
 static void
@@ -134,6 +139,26 @@ bg_pictures_source_class_init (BgPicturesSourceClass *klass)
 }
 
 static void
+remove_placeholder (BgPicturesSource *bg_source, CcBackgroundItem *item)
+{
+  GtkListStore *store;
+  GtkTreeIter iter;
+  GtkTreePath *path;
+  GtkTreeRowReference *row_ref;
+
+  store = bg_source_get_liststore (BG_SOURCE (bg_source));
+  row_ref = g_object_get_data (G_OBJECT (item), "row-ref");
+  if (row_ref == NULL)
+    return;
+
+  path = gtk_tree_row_reference_get_path (row_ref);
+  if (!gtk_tree_model_get_iter (GTK_TREE_MODEL (store), &iter, path))
+    return;
+
+  gtk_list_store_remove (store, &iter);
+}
+
+static void
 picture_scaled (GObject *source_object,
                 GAsyncResult *res,
                 gpointer user_data)
@@ -145,13 +170,19 @@ picture_scaled (GObject *source_object,
   const char *software;
   const char *uri;
   GtkTreeIter iter;
+  GtkTreePath *path;
+  GtkTreeRowReference *row_ref;
   GtkListStore *store;
 
+  item = g_object_get_data (source_object, "item");
   pixbuf = gdk_pixbuf_new_from_stream_finish (res, &error);
   if (pixbuf == NULL)
     {
       if (!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
-        g_warning ("Failed to load image: %s", error->message);
+        {
+          g_warning ("Failed to load image: %s", error->message);
+          remove_placeholder (BG_PICTURES_SOURCE (user_data), item);
+        }
 
       g_error_free (error);
       goto out;
@@ -162,7 +193,6 @@ picture_scaled (GObject *source_object,
    */
   bg_source = BG_PICTURES_SOURCE (user_data);
   store = bg_source_get_liststore (BG_SOURCE (bg_source));
-  item = g_object_get_data (source_object, "item");
   uri = cc_background_item_get_uri (item);
 
   /* Ignore screenshots */
@@ -177,11 +207,26 @@ picture_scaled (GObject *source_object,
 
   cc_background_item_load (item, NULL);
 
-  /* insert the item into the liststore */
-  gtk_list_store_insert_with_values (store, &iter, -1,
-                                     0, pixbuf,
-                                     1, item,
-                                     -1);
+  row_ref = g_object_get_data (G_OBJECT (item), "row-ref");
+  if (row_ref == NULL)
+    {
+      /* insert the item into the liststore if it did not exist */
+      gtk_list_store_insert_with_values (store, NULL, -1,
+                                         0, pixbuf,
+                                         1, item,
+                                         -1);
+    }
+  else
+    {
+      path = gtk_tree_row_reference_get_path (row_ref);
+      if (gtk_tree_model_get_iter (GTK_TREE_MODEL (store), &iter, path))
+        {
+          /* otherwise update the thumbnail */
+          gtk_list_store_set (store, &iter,
+                              0, pixbuf,
+                              -1);
+        }
+    }
 
   g_hash_table_insert (bg_source->priv->known_items,
                        bg_pictures_source_get_unique_filename (uri),
@@ -210,6 +255,7 @@ picture_opened_for_read (GObject *source_object,
         {
           char *filename = g_file_get_path (G_FILE (source_object));
           g_warning ("Failed to load picture '%s': %s", filename, error->message);
+          remove_placeholder (BG_PICTURES_SOURCE (user_data), item);
           g_free (filename);
         }
 
@@ -242,6 +288,16 @@ in_content_types (const char *content_type)
 }
 
 static gboolean
+in_screenshot_types (const char *content_type)
+{
+       guint i;
+       for (i = 0; screenshot_types[i]; i++)
+               if (g_str_equal (screenshot_types[i], content_type))
+                       return TRUE;
+       return FALSE;
+}
+
+static gboolean
 add_single_file (BgPicturesSource *bg_source,
                 GFile            *file,
                 GFileInfo        *info,
@@ -249,6 +305,14 @@ add_single_file (BgPicturesSource *bg_source,
 {
   const gchar *content_type;
   CcBackgroundItem *item = NULL;
+  GError *error = NULL;
+  GdkPixbuf *pixbuf = NULL;
+  GtkIconInfo *icon_info = NULL;
+  GtkIconTheme *theme;
+  GtkListStore *store;
+  GtkTreeIter iter;
+  GtkTreePath *path = NULL;
+  GtkTreeRowReference *row_ref;
   char *uri = NULL;
   gboolean retval = FALSE;
   guint64 mtime;
@@ -275,6 +339,41 @@ add_single_file (BgPicturesSource *bg_source,
   if (source_uri != NULL)
     g_object_set (G_OBJECT (item), "source-url", source_uri, NULL);
 
+  if (in_screenshot_types (content_type))
+    goto read_file;
+
+  theme = gtk_icon_theme_get_default ();
+  icon_info = gtk_icon_theme_lookup_icon (theme,
+                                          "content-loading-symbolic",
+                                          16,
+                                          GTK_ICON_LOOKUP_FORCE_SIZE | GTK_ICON_LOOKUP_GENERIC_FALLBACK);
+  if (icon_info == NULL)
+    {
+      g_warning ("Failed to find placeholder icon");
+      goto read_file;
+    }
+
+  pixbuf = gtk_icon_info_load_icon (icon_info, &error);
+  if (pixbuf == NULL)
+    {
+      g_warning ("Failed to load placeholder icon: %s", error->message);
+      g_clear_error (&error);
+      goto read_file;
+    }
+
+  store = bg_source_get_liststore (BG_SOURCE (bg_source));
+
+  /* insert the item into the liststore */
+  gtk_list_store_insert_with_values (store, &iter, -1,
+                                     0, pixbuf,
+                                     1, item,
+                                     -1);
+
+  path = gtk_tree_model_get_path (GTK_TREE_MODEL (store), &iter);
+  row_ref = gtk_tree_row_reference_new (GTK_TREE_MODEL (store), path);
+  g_object_set_data_full (G_OBJECT (item), "row-ref", row_ref, (GDestroyNotify) gtk_tree_row_reference_free);
+
+ read_file:
   g_object_set_data_full (G_OBJECT (file), "item", g_object_ref (item), g_object_unref);
 
   g_file_read_async (file, G_PRIORITY_DEFAULT,
@@ -284,6 +383,9 @@ add_single_file (BgPicturesSource *bg_source,
   retval = TRUE;
 
  out:
+  gtk_tree_path_free (path);
+  g_clear_object (&pixbuf);
+  g_clear_object (&icon_info);
   g_clear_object (&item);
   g_object_unref (file);
   g_free (uri);