Make message handling overridable.

Original commit message from CVS:
* docs/design/part-TODO.txt:
* gst/gstbin.c: (gst_bin_class_init), (gst_bin_provide_clock_func),
(gst_bin_add_func), (gst_bin_remove_func), (bin_bus_handler),
(gst_bin_handle_message_func):
* gst/gstbin.h:
Make message handling overridable.

ChangeLog

@@ -1,3 +1,12 @@
+2005-11-19  Wim Taymans  <wim@fluendo.com>
+
+	* docs/design/part-TODO.txt:
+	* gst/gstbin.c: (gst_bin_class_init), (gst_bin_provide_clock_func),
+	(gst_bin_add_func), (gst_bin_remove_func), (bin_bus_handler),
+	(gst_bin_handle_message_func):
+	* gst/gstbin.h:
+	Make message handling overridable.
+
 2005-11-19  Andy Wingo  <wingo@pobox.com>
 
 	* gst/gstpad.h (GST_PAD_IS_USABLE): Removed. Fixes #321235.

docs/design/part-TODO.txt

@@ -9,17 +9,6 @@ API/ABI
 
 - convert framerate to GstFraction in GstCaps.
 
-- implement latency calculation for live sources.
-
-- implement master/slave clocks.
-
-- implement QOS.
-
-- implement BUFFERSIZE.
-
-- make bin_bus_handler a vmethod so subclasses can use their own implementation
-  or chain to the parent.
-
 - make it possible to seek on other formats than bytes in basesrc.
 
 - GstFormat, GstQuery quarks, get_name. 
@@ -47,7 +36,13 @@ API/ABI
 IMPLEMENTATION
 --------------
 
-- implement clock selection as explained in part-gstpipeline.txt. 
+- implement latency calculation for live sources.
+
+- implement master/slave clocks.
+
+- implement QOS.
+
+- implement BUFFERSIZE.
 
 
 DESIGN

gst/gstbin.c

@@ -147,6 +147,7 @@ static void gst_bin_set_index_func (GstElement * element, GstIndex * index);
 static GstClock *gst_bin_provide_clock_func (GstElement * element);
 static void gst_bin_set_clock_func (GstElement * element, GstClock * clock);
 
+static void gst_bin_handle_message_func (GstBin * bin, GstMessage * message);
 static gboolean gst_bin_send_event (GstElement * element, GstEvent * event);
 static GstBusSyncReply bin_bus_handler (GstBus * bus,
     GstMessage * message, GstBin * bin);
@@ -336,6 +337,7 @@ gst_bin_class_init (GstBinClass * klass)
 
   klass->add_element = GST_DEBUG_FUNCPTR (gst_bin_add_func);
   klass->remove_element = GST_DEBUG_FUNCPTR (gst_bin_remove_func);
+  klass->handle_message = GST_DEBUG_FUNCPTR (gst_bin_handle_message_func);
 
   GST_DEBUG ("creating bin thread pool");
   err = NULL;
@@ -497,7 +499,7 @@ gst_bin_provide_clock_func (GstElement * element)
   }
   gst_object_replace ((GstObject **) & bin->provided_clock,
       (GstObject *) result);
-  gst_object_replace ((GstObject **) & bin->ABI.clock_provider,
+  gst_object_replace ((GstObject **) & bin->clock_provider,
       (GstObject *) provider);
   bin->clock_dirty = FALSE;
   GST_DEBUG_OBJECT (bin, "provided new clock %p", result);
@@ -871,7 +873,7 @@ gst_bin_remove_func (GstBin * bin, GstElement * element)
   /* if the clock provider for this element is removed, we lost
    * the clock as well, we need to inform the parent of this
    * so that it can select a new clock */
-  if (bin->ABI.clock_provider == element) {
+  if (bin->clock_provider == element) {
     GST_DEBUG_OBJECT (bin, "element \"%s\" provided the clock", elem_name);
     bin->clock_dirty = TRUE;
     clock_message =
@@ -1839,6 +1841,21 @@ gst_bin_recalc_func (GstBin * bin, gpointer data)
  */
 static GstBusSyncReply
 bin_bus_handler (GstBus * bus, GstMessage * message, GstBin * bin)
+{
+
+  GstBinClass *bclass;
+
+  bclass = GST_BIN_GET_CLASS (bin);
+  if (bclass->handle_message)
+    bclass->handle_message (bin, message);
+  else
+    gst_message_unref (message);
+
+  return GST_BUS_DROP;
+}
+
+static void
+gst_bin_handle_message_func (GstBin * bin, GstMessage * message)
 {
   GST_DEBUG_OBJECT (bin, "[msg %p] handling child message of type %s",
       message, gst_message_type_get_name (GST_MESSAGE_TYPE (message)));
@@ -1994,14 +2011,14 @@ bin_bus_handler (GstBus * bus, GstMessage * message, GstBin * bin)
       goto forward;
   }
 
-  return GST_BUS_DROP;
+  return;
 
 forward:
   {
     /* Send all other messages upward */
     GST_DEBUG_OBJECT (bin, "posting message upward");
     gst_element_post_message (GST_ELEMENT_CAST (bin), message);
-    return GST_BUS_DROP;
+    return;
   }
 }
 

gst/gstbin.h

@@ -88,6 +88,7 @@ typedef struct _GstBinClass GstBinClass;
  * @state_dirty: the bin needs to recalculate its state
  * @clock_dirty: the bin needs to select a new clock
  * @provided_clock: the last clock selected
+ * @clock_provider: the element that provided @provided_clock
  *
  * The GstBin base class. Subclasses can access these fields provided
  * the LOCK is taken.
@@ -110,14 +111,10 @@ struct _GstBin {
 
   gboolean       clock_dirty;
   GstClock	*provided_clock;
+  GstElement    *clock_provider;
 
   /*< private >*/
-  union {
+  gpointer _gst_reserved[GST_PADDING];
-    struct {
-      GstElement *clock_provider;
-    } ABI;
-    gpointer _gst_reserved[GST_PADDING+1-1];
-  };
 };
 
 /**
@@ -125,9 +122,13 @@ struct _GstBin {
  * @parent_class: bin parent class
  * @add_element: method to add an element to a bin
  * @remove_element: method to remove an element from a bin
+ * @handle_message: method to handle a message from the children
  *
  * Subclasses can override the @add_element and @remove_element to
  * update the list of children in the bin.
+ *
+ * The @handle_message method can be overriden to implement custom
+ * message handling.
  */
 struct _GstBinClass {
   GstElementClass parent_class;
@@ -144,6 +145,8 @@ struct _GstBinClass {
   gboolean	(*add_element)		(GstBin *bin, GstElement *element);
   gboolean	(*remove_element)	(GstBin *bin, GstElement *element);
 
+  void		(*handle_message)	(GstBin *bin, GstMessage *message);
+
   /*< private >*/
   gpointer _gst_reserved[GST_PADDING];
 };