[libchamplain] Make it possible to manually chain chains.

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

commit 191394a29db4da0ee4bb3c1121d4bd28d711ff16
Author: JiÅ?í Techet <techet gmail com>
Date:   Tue Feb 2 00:08:47 2010 +0100

    Make it possible to manually chain chains.
    
    Chains should behave as other map sources so it should be possible
    to create chains of chains. For now, chains of chains have to be
    created manually - i.e. the outer chain cannot be ChamplainMapSourceChain
    but has to be created by _set_next_source(). The reason is that
    a chain has to know about each of its elements whether it is a map
    source or a cache (if this feature is desirable, we can add a virtual
    method of map sources that determines whether it behaves as a map source
    or cache so even if the map source is a chain, it could have this
    information attached).
    
    Signed-off-by: JiÅ?í Techet <techet gmail com>

 champlain/champlain-map-source-chain.c |   79 ++++++++++++++++++++++++--------
 champlain/champlain-map-source.c       |   35 ++++++++++----
 champlain/champlain-map-source.h       |    4 ++
 3 files changed, 89 insertions(+), 29 deletions(-)
---
diff --git a/champlain/champlain-map-source-chain.c b/champlain/champlain-map-source-chain.c
index 38a97e1..84e15c6 100644
--- a/champlain/champlain-map-source-chain.c
+++ b/champlain/champlain-map-source-chain.c
@@ -43,6 +43,7 @@ typedef struct _ChamplainMapSourceChainPrivate ChamplainMapSourceChainPrivate;
 struct _ChamplainMapSourceChainPrivate
 {
   ChamplainMapSource *stack_top;
+  ChamplainMapSource *stack_bottom;
   gulong sig_handler_id;
 };
 
@@ -55,6 +56,9 @@ static guint get_max_zoom_level (ChamplainMapSource *map_source);
 static guint get_tile_size (ChamplainMapSource *map_source);
 
 static void fill_tile (ChamplainMapSource *map_source, ChamplainTile *tile);
+static void on_set_next_source (ChamplainMapSource *map_source,
+                                ChamplainMapSource *old_next_source,
+                                ChamplainMapSource *new_next_source);
 
 static void
 champlain_map_source_chain_dispose (GObject *object)
@@ -95,6 +99,7 @@ champlain_map_source_chain_class_init (ChamplainMapSourceChainClass *klass)
   map_source_class->get_tile_size = get_tile_size;
 
   map_source_class->fill_tile = fill_tile;
+  map_source_class->on_set_next_source = on_set_next_source;
 }
 
 static void
@@ -102,7 +107,7 @@ champlain_map_source_chain_init (ChamplainMapSourceChain *source_chain)
 {
   ChamplainMapSourceChainPrivate *priv = GET_PRIVATE(source_chain);
   priv->stack_top = NULL;
-  priv->sig_handler_id = 0;
+  priv->stack_bottom = NULL;
 }
 
 /**
@@ -114,7 +119,8 @@ champlain_map_source_chain_init (ChamplainMapSourceChain *source_chain)
  *
  * Since: 0.6
  */
-ChamplainMapSourceChain* champlain_map_source_chain_new (void)
+ChamplainMapSourceChain*
+champlain_map_source_chain_new (void)
 {
   return g_object_new (CHAMPLAIN_TYPE_MAP_SOURCE_CHAIN, NULL);
 }
@@ -203,8 +209,9 @@ get_tile_size (ChamplainMapSource *map_source)
   return champlain_map_source_get_tile_size (priv->stack_top);
 }
 
-static void fill_tile (ChamplainMapSource *map_source,
-                       ChamplainTile *tile)
+static void
+fill_tile (ChamplainMapSource *map_source,
+           ChamplainTile *tile)
 {
   ChamplainMapSourceChain *source_chain = CHAMPLAIN_MAP_SOURCE_CHAIN (map_source);
   g_return_if_fail (source_chain);
@@ -215,10 +222,27 @@ static void fill_tile (ChamplainMapSource *map_source,
   champlain_map_source_fill_tile (priv->stack_top, tile);
 }
 
-static void assign_cache_of_next_source_sequence (ChamplainMapSource *start_map_source, ChamplainTileCache *tile_cache)
+static void
+on_set_next_source (ChamplainMapSource *map_source,
+                    ChamplainMapSource *old_next_source,
+                    ChamplainMapSource *new_next_source)
+{
+  ChamplainMapSourceChain *source_chain = CHAMPLAIN_MAP_SOURCE_CHAIN (map_source);
+  ChamplainMapSourceChainPrivate *priv = GET_PRIVATE(source_chain);
+
+  g_return_if_fail (source_chain);
+
+  if (priv->stack_bottom)
+    champlain_map_source_set_next_source (priv->stack_bottom, new_next_source);
+}
+
+static void
+assign_cache_of_next_source_sequence (ChamplainMapSourceChain *source_chain,
+                                      ChamplainMapSource *start_map_source,
+                                      ChamplainTileCache *tile_cache)
 {
   ChamplainMapSource *map_source = start_map_source;
-  ChamplainTileSource *tile_source;
+  ChamplainMapSource *chain_next_source = champlain_map_source_get_next_source (CHAMPLAIN_MAP_SOURCE(source_chain));
 
   do
     {
@@ -226,17 +250,15 @@ static void assign_cache_of_next_source_sequence (ChamplainMapSource *start_map_
     }
   while (CHAMPLAIN_IS_TILE_CACHE(map_source));
 
-  tile_source = CHAMPLAIN_TILE_SOURCE(map_source);
-  while (tile_source)
+  while (CHAMPLAIN_IS_TILE_SOURCE(map_source) && map_source != chain_next_source)
     {
-      champlain_tile_source_set_cache (tile_source, tile_cache);
+      champlain_tile_source_set_cache (CHAMPLAIN_TILE_SOURCE(map_source), tile_cache);
       map_source = champlain_map_source_get_next_source (map_source);
-      tile_source = CHAMPLAIN_TILE_SOURCE(map_source);
     }
 }
 
-static
-void reload_tiles_cb (ChamplainMapSource *map_source, ChamplainMapSourceChain *source_chain)
+static void
+reload_tiles_cb (ChamplainMapSource *map_source, ChamplainMapSourceChain *source_chain)
 {
   /* propagate the signal from the chain that is inside champlain_map_source_chain */
   g_signal_emit_by_name (source_chain, "reload-tiles", NULL);
@@ -251,7 +273,8 @@ void reload_tiles_cb (ChamplainMapSource *map_source, ChamplainMapSourceChain *s
  *
  * Since: 0.6
  */
-void champlain_map_source_chain_push (ChamplainMapSourceChain *source_chain, ChamplainMapSource *map_source)
+void
+champlain_map_source_chain_push (ChamplainMapSourceChain *source_chain, ChamplainMapSource *map_source)
 {
   ChamplainMapSourceChainPrivate *priv = GET_PRIVATE(source_chain);
   gboolean is_cache = FALSE;
@@ -265,9 +288,15 @@ void champlain_map_source_chain_push (ChamplainMapSourceChain *source_chain, Cha
 
   if (!priv->stack_top)
     {
+      ChamplainMapSource *chain_next_source = champlain_map_source_get_next_source (CHAMPLAIN_MAP_SOURCE(source_chain));
+
       /* tile source has to be last */
       g_return_if_fail (!is_cache);
+
       priv->stack_top = map_source;
+      priv->stack_bottom = map_source;
+      if (chain_next_source)
+        champlain_map_source_set_next_source (priv->stack_bottom, chain_next_source);
     }
   else
     {
@@ -280,7 +309,7 @@ void champlain_map_source_chain_push (ChamplainMapSourceChain *source_chain, Cha
       if (is_cache)
         {
           ChamplainTileCache *tile_cache = CHAMPLAIN_TILE_CACHE(map_source);
-          assign_cache_of_next_source_sequence (priv->stack_top, tile_cache);
+          assign_cache_of_next_source_sequence (source_chain, priv->stack_top, tile_cache);
         }
     }
 
@@ -296,10 +325,12 @@ void champlain_map_source_chain_push (ChamplainMapSourceChain *source_chain, Cha
  *
  * Since: 0.6
  */
-void champlain_map_source_chain_pop (ChamplainMapSourceChain *source_chain)
+void
+champlain_map_source_chain_pop (ChamplainMapSourceChain *source_chain)
 {
   ChamplainMapSourceChainPrivate *priv = GET_PRIVATE(source_chain);
   ChamplainMapSource *old_stack_top = priv->stack_top;
+  ChamplainMapSource *next_source = champlain_map_source_get_next_source (priv->stack_top);
 
   g_return_if_fail (priv->stack_top);
 
@@ -308,16 +339,24 @@ void champlain_map_source_chain_pop (ChamplainMapSourceChain *source_chain)
 
   if (CHAMPLAIN_IS_TILE_CACHE(priv->stack_top))
     {
-      ChamplainMapSource *map_source = champlain_map_source_get_next_source (priv->stack_top);
       ChamplainTileCache *tile_cache = NULL;
 
-      if (CHAMPLAIN_IS_TILE_CACHE(map_source))
-        tile_cache = CHAMPLAIN_TILE_CACHE(map_source);
+      if (CHAMPLAIN_IS_TILE_CACHE(next_source))
+        tile_cache = CHAMPLAIN_TILE_CACHE(next_source);
 
-      assign_cache_of_next_source_sequence (priv->stack_top, tile_cache);
+      /* _push() guarantees that the last source is tile_source so we can be
+         sure that the next map source is still within the chain */
+      assign_cache_of_next_source_sequence (source_chain, priv->stack_top, tile_cache);
     }
 
-  priv->stack_top = champlain_map_source_get_next_source (priv->stack_top);
+  if (next_source == champlain_map_source_get_next_source (CHAMPLAIN_MAP_SOURCE(source_chain)))
+  {
+    priv->stack_top = NULL;
+    priv->stack_bottom = NULL;
+  }
+  else
+    priv->stack_top = next_source;
+
   if (priv->stack_top)
     {
       priv->sig_handler_id = g_signal_connect (priv->stack_top, "reload-tiles",
diff --git a/champlain/champlain-map-source.c b/champlain/champlain-map-source.c
index 98c0c7c..613fe45 100644
--- a/champlain/champlain-map-source.c
+++ b/champlain/champlain-map-source.c
@@ -83,6 +83,9 @@ struct _ChamplainMapSourcePrivate
 };
 
 static void reload_tiles_cb (ChamplainMapSource *orig, ChamplainMapSource *self);
+static void on_set_next_source (ChamplainMapSource *map_source,
+                                ChamplainMapSource *old_next_source,
+                                ChamplainMapSource *new_next_source);
 
 static void
 champlain_map_source_get_property (GObject *object,
@@ -173,6 +176,7 @@ champlain_map_source_class_init (ChamplainMapSourceClass *klass)
   klass->get_projection = NULL;
 
   klass->fill_tile = NULL;
+  klass->on_set_next_source = on_set_next_source;
 
   /**
   * ChamplainMapSource:next-source:
@@ -238,6 +242,25 @@ void reload_tiles_cb (ChamplainMapSource *orig, ChamplainMapSource *self)
   g_signal_emit_by_name (self, "reload-tiles", NULL);
 }
 
+static void
+on_set_next_source (ChamplainMapSource *map_source,
+                    ChamplainMapSource *old_next_source,
+                    ChamplainMapSource *new_next_source)
+{
+  ChamplainMapSourcePrivate *priv = GET_PRIVATE(map_source);
+  if (old_next_source)
+    {
+      if (g_signal_handler_is_connected (old_next_source, priv->sig_handler_id))
+        g_signal_handler_disconnect (old_next_source, priv->sig_handler_id);
+    }
+
+  if (new_next_source)
+    {
+      priv->sig_handler_id = g_signal_connect (new_next_source, "reload-tiles",
+                             G_CALLBACK (reload_tiles_cb), map_source);
+    }
+}
+
 /**
  * champlain_map_source_set_next_source:
  * @map_source: a #ChamplainMapSource
@@ -255,22 +278,16 @@ champlain_map_source_set_next_source (ChamplainMapSource *map_source,
 
   ChamplainMapSourcePrivate *priv = GET_PRIVATE(map_source);
 
-  if (priv->next_source != NULL)
-    {
-      if (g_signal_handler_is_connected (priv->next_source, priv->sig_handler_id))
-        g_signal_handler_disconnect (priv->next_source, priv->sig_handler_id);
+  CHAMPLAIN_MAP_SOURCE_GET_CLASS (map_source)->on_set_next_source (map_source, priv->next_source, next_source);
 
-      g_object_unref (priv->next_source);
-    }
+  if (priv->next_source != NULL)
+    g_object_unref (priv->next_source);
 
   if (next_source)
     {
       g_return_if_fail (CHAMPLAIN_IS_MAP_SOURCE (next_source));
 
       g_object_ref_sink (next_source);
-
-      priv->sig_handler_id = g_signal_connect (next_source, "reload-tiles",
-                             G_CALLBACK (reload_tiles_cb), map_source);
     }
 
   priv->next_source = next_source;
diff --git a/champlain/champlain-map-source.h b/champlain/champlain-map-source.h
index c05cc7b..0bb422d 100644
--- a/champlain/champlain-map-source.h
+++ b/champlain/champlain-map-source.h
@@ -63,6 +63,10 @@ struct _ChamplainMapSourceClass
 
   void (*fill_tile) (ChamplainMapSource *map_source,
                      ChamplainTile *tile);
+
+  void (*on_set_next_source) (ChamplainMapSource *map_source,
+                              ChamplainMapSource *next_source,
+                              ChamplainMapSource *new_next_source);
 };
 
 GType champlain_map_source_get_type (void);