[libchamplain] Fix asynchronous tile loading

[Pierre-Luc Beaudoin <plbeaudoin src gnome org>]

commit e115ad56dabca6a2f8b1a882bfc6d8379d50ff54
Author: JiÅ?í Techet <techet gmail com>
Date:   Sun Feb 14 13:21:46 2010 +0100

    Fix asynchronous tile loading
    
    When loading textures asynchronously, we have to check whether the
    tile was loaded successfully in the callback.
    
    Signed-off-by: JiÅ?í Techet <techet gmail com>

 champlain/champlain-file-cache.c |  101 ++++++++++++++++++++++++++------------
 champlain/champlain-view.c       |    6 ++-
 2 files changed, 75 insertions(+), 32 deletions(-)
---
diff --git a/champlain/champlain-file-cache.c b/champlain/champlain-file-cache.c
index 788a55e..0c8b915 100644
--- a/champlain/champlain-file-cache.c
+++ b/champlain/champlain-file-cache.c
@@ -225,7 +225,7 @@ init_cache  (ChamplainFileCache *file_cache)
   gint error;
 
   g_print ("init! '%d'\n", champlain_tile_cache_get_persistent (tile_cache));
-  
+
   g_return_if_fail (create_cache_dir (priv->cache_dir));
 
   if (champlain_tile_cache_get_persistent (tile_cache))
@@ -542,47 +542,42 @@ tile_is_expired (ChamplainFileCache *file_cache, ChamplainTile *tile)
   return validate_cache;
 }
 
-static void
-fill_tile (ChamplainMapSource *map_source,
-           ChamplainTile *tile)
+typedef struct
 {
-  g_return_if_fail (CHAMPLAIN_IS_FILE_CACHE (map_source));
-  g_return_if_fail (CHAMPLAIN_IS_TILE (tile));
+  ChamplainMapSource *map_source;
+  ChamplainTile *tile;
+  gchar *filename;
+  gulong handler;
+} TileLoadedCallbackData;
 
+static void
+tile_loaded_cb (ClutterTexture *texture,
+                const GError *error,
+                TileLoadedCallbackData *user_data)
+{
+  ChamplainMapSource *map_source = user_data->map_source;
+  gchar *filename = user_data->filename;
+  ChamplainTile *tile = user_data->tile;
   ChamplainFileCache *file_cache = CHAMPLAIN_FILE_CACHE(map_source);
   ChamplainMapSource *next_source = champlain_map_source_get_next_source (map_source);
   ChamplainFileCachePrivate *priv = GET_PRIVATE (file_cache);
   GFileInfo *info = NULL;
   GFile *file = NULL;
-  GError *gerror = NULL;
-  ClutterActor *actor = NULL;
-  gchar *filename = NULL;
+  ClutterActor *actor = CLUTTER_ACTOR(texture);
   GTimeVal modified_time = {0,};
 
-  if (champlain_tile_get_content (tile))
-    /* Previous cache in the chain is validating its contents */
-    goto load_next;
-
-  filename = get_filename (file_cache, tile);
-  DEBUG ("fill of %s", filename);
+  g_signal_handler_disconnect (texture, user_data->handler);
+  g_free (user_data);
 
-  /* Load the cached version */
-  actor = clutter_texture_new ();
-  clutter_texture_set_load_async (CLUTTER_TEXTURE (actor), TRUE);
-  clutter_texture_set_from_file (CLUTTER_TEXTURE (actor), filename, &gerror);
-  if (actor)
+  if (error)
     {
-      champlain_tile_set_content (tile, actor, FALSE);
-      champlain_tile_set_size (tile, champlain_map_source_get_tile_size (map_source));
-    }
-  else
-    {
-      DEBUG ("Failed to load tile %s, error: %s",
-             filename, gerror->message);
-      g_error_free (gerror);
+      DEBUG ("Failed to load tile %s, error: %s", filename, error->message);
       goto load_next;
     }
 
+  champlain_tile_set_content (tile, actor, FALSE);
+  champlain_tile_set_size (tile, champlain_map_source_get_tile_size (map_source));
+
   /* Retrieve modification time */
   file = g_file_new_for_path (filename);
   info = g_file_query_info (file,
@@ -599,9 +594,7 @@ fill_tile (ChamplainMapSource *map_source,
 
   /* Notify other caches that the tile has been filled */
   if (CHAMPLAIN_IS_TILE_CACHE(next_source))
-    {
-      on_tile_filled (CHAMPLAIN_TILE_CACHE(next_source), tile);
-    }
+    on_tile_filled (CHAMPLAIN_TILE_CACHE(next_source), tile);
 
   if (tile_is_expired (file_cache, tile))
     {
@@ -657,6 +650,52 @@ load_next:
 cleanup:
   sqlite3_reset (priv->stmt_select);
   g_free (filename);
+  g_object_unref (tile);
+  g_object_unref (map_source);
+}
+
+static void
+fill_tile (ChamplainMapSource *map_source,
+           ChamplainTile *tile)
+{
+  g_return_if_fail (CHAMPLAIN_IS_FILE_CACHE (map_source));
+  g_return_if_fail (CHAMPLAIN_IS_TILE (tile));
+
+  if (!champlain_tile_get_content (tile))
+    {
+      ChamplainFileCache *file_cache = CHAMPLAIN_FILE_CACHE(map_source);
+      TileLoadedCallbackData *callback_data;
+      ClutterTexture *texture;
+
+      callback_data = g_new (TileLoadedCallbackData, 1);
+      callback_data->tile = tile;
+      callback_data->map_source = map_source;
+      callback_data->filename = get_filename (file_cache, tile);
+
+      DEBUG ("fill of %s", callback_data->filename);
+
+      /* Ref the tile as it may be freeing during the loading
+       * Unref when the loading is done.
+       */
+      g_object_ref (tile);
+      g_object_ref (map_source);
+
+      /* Load the cached version */
+      texture = CLUTTER_TEXTURE(clutter_texture_new ());
+      callback_data->handler = g_signal_connect (texture, "load-finished",
+                               G_CALLBACK (tile_loaded_cb),
+                               callback_data);
+      clutter_texture_set_load_async (texture, TRUE);
+      clutter_texture_set_from_file (texture, callback_data->filename, NULL);
+    }
+  else
+    {
+      ChamplainMapSource *next_source = champlain_map_source_get_next_source (map_source);
+
+      /* Previous cache in the chain is validating its contents */
+      if (CHAMPLAIN_IS_MAP_SOURCE(next_source))
+        champlain_map_source_fill_tile (next_source, tile);
+    }
 }
 
 static void
diff --git a/champlain/champlain-view.c b/champlain/champlain-view.c
index bed6b66..e75d4d9 100644
--- a/champlain/champlain-view.c
+++ b/champlain/champlain-view.c
@@ -333,7 +333,7 @@ update_viewport (ChamplainView *view,
     g_object_notify (G_OBJECT (view), "latitude");
 }
 
-static void 
+static void
 panning_completed (TidyFingerScroll *scroll,
                    ChamplainView *view)
 {
@@ -2389,6 +2389,7 @@ view_load_visible_tiles (ChamplainView *view)
                           champlain_tile_get_actor (tile), NULL);
 
                       champlain_zoom_level_add_tile (level, tile);
+                      champlain_tile_set_state (tile, CHAMPLAIN_STATE_LOADING);
                       champlain_map_source_fill_tile (priv->map_source, tile);
 
                       g_object_unref (tile);
@@ -2497,7 +2498,10 @@ view_reload_tiles_cb (ChamplainMapSource *map_source,
         continue;
 
       if (champlain_tile_get_state (tile) != CHAMPLAIN_STATE_LOADING)
+      {
+        champlain_tile_set_state (tile, CHAMPLAIN_STATE_LOADING);
         champlain_map_source_fill_tile (priv->map_source, tile);
+      }
     }
   view_update_state (view);
 }