GstPad: Add GST_PAD_NEGOTIABLE GstPadFlag

A pad is 'negotiable' when its container element is in a state greater
than GST_STATE_READY

API:gst_pad_is_negotiable
API:gst_pad_set_negotiable
API:GST_PAD_NEGOTIABLE

https://bugzilla.gnome.org/show_bug.cgi?id=618644

docs/gst/gstreamer-sections.txt

@@ -1372,6 +1372,9 @@ gst_pad_use_fixed_caps
 
 gst_pad_is_active
 
+gst_pad_is_negotiable
+gst_pad_set_negotiable
+
 gst_pad_set_blocked
 gst_pad_set_blocked_async
 gst_pad_set_blocked_async_full
@@ -1561,6 +1564,9 @@ GST_PAD_IS_BLOCKED
 GST_PAD_IS_BLOCKING
 GST_PAD_IS_IN_SETCAPS
 GST_PAD_SET_FLUSHING
+GST_PAD_IS_NEGOTIABLE
+GST_PAD_SET_NEGOTIABLE
+GST_PAD_UNSET_NEGOTIABLE
 GST_PAD_TASK
 GST_PAD_UNSET_FLUSHING
 

gst/gstelement.c

@@ -686,7 +686,7 @@ gboolean
 gst_element_add_pad (GstElement * element, GstPad * pad)
 {
   gchar *pad_name;
-  gboolean flushing;
+  gboolean flushing, negotiable;
 
   g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
   g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
@@ -697,6 +697,7 @@ gst_element_add_pad (GstElement * element, GstPad * pad)
   GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
       GST_STR_NULL (pad_name));
   flushing = GST_PAD_IS_FLUSHING (pad);
+  negotiable = GST_PAD_IS_NEGOTIABLE (pad);
   GST_OBJECT_UNLOCK (pad);
 
   /* then check to see if there's already a pad by that name here */
@@ -709,6 +710,14 @@ gst_element_add_pad (GstElement * element, GstPad * pad)
               GST_OBJECT_CAST (element))))
     goto had_parent;
 
+  /* sync pad state with element */
+  if (!negotiable && (GST_STATE (element) > GST_STATE_NULL ||
+          GST_STATE_NEXT (element) == GST_STATE_READY)) {
+    GST_OBJECT_LOCK (pad);
+    GST_PAD_SET_NEGOTIABLE (pad);
+    GST_OBJECT_UNLOCK (pad);
+  }
+
   /* check for flushing pads */
   if (flushing && (GST_STATE (element) > GST_STATE_READY ||
           GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
@@ -2668,6 +2677,51 @@ done:
   return g_value_get_boolean (&ret);
 }
 
+static gboolean
+negotiable_pads (GstPad * pad, GValue * ret, gboolean * active)
+{
+  if (!gst_pad_set_negotiable (pad, *active))
+    g_value_set_boolean (ret, FALSE);
+
+  /* unref the object that was reffed for us by _fold */
+  gst_object_unref (pad);
+  return TRUE;
+}
+
+/* is called with STATE_LOCK */
+static gboolean
+gst_element_pads_negotiable (GstElement * element, gboolean negotiable)
+{
+  GstIterator *iter;
+  gboolean res;
+
+  GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
+      "pads_negotiable with negotiable %d", negotiable);
+
+  /* clear the caps on all pads, this should never fail */
+  iter = gst_element_iterate_pads (element);
+  res =
+      iterator_activate_fold_with_resync (iter,
+      (GstIteratorFoldFunction) negotiable_pads, &negotiable);
+  gst_iterator_free (iter);
+  if (G_UNLIKELY (!res))
+    goto negotiable_failed;
+
+  GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
+      "pads_negotiable successful");
+
+  return TRUE;
+
+  /* ERRORS */
+negotiable_failed:
+  {
+    GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
+        "failed to set pads to 'negotiable'");
+    return FALSE;
+  }
+}
+
+
 /* is called with STATE_LOCK
  *
  * Pads are activated from source pads to sinkpads.
@@ -2758,6 +2812,9 @@ gst_element_change_state_func (GstElement * element, GstStateChange transition)
 
   switch (transition) {
     case GST_STATE_CHANGE_NULL_TO_READY:
+      if (!gst_element_pads_negotiable (element, TRUE)) {
+        result = GST_STATE_CHANGE_FAILURE;
+      }
       break;
     case GST_STATE_CHANGE_READY_TO_PAUSED:
       if (!gst_element_pads_activate (element, TRUE)) {
@@ -2777,6 +2834,7 @@ gst_element_change_state_func (GstElement * element, GstStateChange transition)
       } else {
         gst_element_set_base_time (element, 0);
       }
+      gst_element_pads_negotiable (element, FALSE);
 
       /* In null state release the reference to the clock */
       GST_OBJECT_LOCK (element);

gst/gstpad.c

@@ -983,6 +983,62 @@ gst_pad_is_active (GstPad * pad)
   return result;
 }
 
+/**
+ * gst_pad_is_negotiable:
+ * @pad: the #GstPad to query
+ *
+ * Query if a pad is negotiable
+ *
+ * Returns: TRUE if the pad is negotiable.
+ *
+ * MT safe.
+ *
+ * Since: 0.10.30
+ */
+gboolean
+gst_pad_is_negotiable (GstPad * pad)
+{
+  gboolean result = FALSE;
+
+  g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
+
+  GST_OBJECT_LOCK (pad);
+  result = GST_PAD_IS_NEGOTIABLE (pad);
+  GST_OBJECT_UNLOCK (pad);
+
+  return result;
+}
+
+/**
+ * gst_pad_set_negotiable:
+ * @pad: the #GstPad to set negotiable or not
+ * @negotiable: whether or not the pad should be set negotiable or not
+ *
+ * Sets a pad 'negotiable' if @negotiable is TRUE. A pad in that state will
+ * forward pad queries. Pads are set to negotiable by their container element in
+ * GST_STATE_READY and unset in GST_STATE_NULL.
+ *
+ * MT safe.
+ *
+ * Returns: #TRUE if the operation was successfull.
+ *
+ * Since: 0.10.30
+ */
+gboolean
+gst_pad_set_negotiable (GstPad * pad, gboolean negotiable)
+{
+  g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
+
+  GST_OBJECT_LOCK (pad);
+  if (negotiable)
+    GST_PAD_SET_NEGOTIABLE (pad);
+  else
+    GST_PAD_UNSET_NEGOTIABLE (pad);
+  GST_OBJECT_UNLOCK (pad);
+
+  return TRUE;
+}
+
 /**
  * gst_pad_set_blocked_async_full:
  * @pad: the #GstPad to block or unblock

gst/gstpad.h

@@ -541,6 +541,7 @@ typedef enum {
  * @GST_PAD_IN_GETCAPS: GstPadGetCapsFunction() is running now
  * @GST_PAD_IN_SETCAPS: GstPadSetCapsFunction() is running now
  * @GST_PAD_BLOCKING: is pad currently blocking on a buffer or event
+ * @GST_PAD_NEGOTIABLE: can pad handle caps requests. Since 0.10.30
  * @GST_PAD_FLAG_LAST: offset to define more flags
  *
  * Pad state flags
@@ -551,6 +552,7 @@ typedef enum {
   GST_PAD_IN_GETCAPS    = (GST_OBJECT_FLAG_LAST << 2),
   GST_PAD_IN_SETCAPS    = (GST_OBJECT_FLAG_LAST << 3),
   GST_PAD_BLOCKING	= (GST_OBJECT_FLAG_LAST << 4),
+  GST_PAD_NEGOTIABLE    = (GST_OBJECT_FLAG_LAST << 5),
   /* padding */
   GST_PAD_FLAG_LAST     = (GST_OBJECT_FLAG_LAST << 8)
 } GstPadFlags;
@@ -746,12 +748,16 @@ struct _GstPadClass {
 #define GST_PAD_IS_FLUSHING(pad)	(GST_OBJECT_FLAG_IS_SET (pad, GST_PAD_FLUSHING))
 #define GST_PAD_IS_IN_GETCAPS(pad)	(GST_OBJECT_FLAG_IS_SET (pad, GST_PAD_IN_GETCAPS))
 #define GST_PAD_IS_IN_SETCAPS(pad)	(GST_OBJECT_FLAG_IS_SET (pad, GST_PAD_IN_SETCAPS))
+#define GST_PAD_IS_NEGOTIABLE(pad)      (GST_OBJECT_FLAG_IS_SET (pad, GST_PAD_NEGOTIABLE))
 #define GST_PAD_IS_SRC(pad)		(GST_PAD_DIRECTION(pad) == GST_PAD_SRC)
 #define GST_PAD_IS_SINK(pad)		(GST_PAD_DIRECTION(pad) == GST_PAD_SINK)
 
 #define GST_PAD_SET_FLUSHING(pad)	(GST_OBJECT_FLAG_SET (pad, GST_PAD_FLUSHING))
 #define GST_PAD_UNSET_FLUSHING(pad)	(GST_OBJECT_FLAG_UNSET (pad, GST_PAD_FLUSHING))
 
+#define GST_PAD_SET_NEGOTIABLE(pad)          (GST_OBJECT_FLAG_SET (pad, GST_PAD_NEGOTIABLE))
+#define GST_PAD_UNSET_NEGOTIABLE(pad)        (GST_OBJECT_FLAG_UNSET (pad, GST_PAD_NEGOTIABLE))
+
 /**
  * GST_PAD_GET_STREAM_LOCK:
  * @pad: a #GstPad
@@ -971,6 +977,9 @@ gboolean		gst_pad_query_default			(GstPad *pad, GstQuery *query);
 gboolean		gst_pad_dispatcher			(GstPad *pad, GstPadDispatcherFunction dispatch,
 								 gpointer data);
 
+gboolean                gst_pad_is_negotiable			(GstPad *pad);
+gboolean                gst_pad_set_negotiable			(GstPad *pad, gboolean negotiable);
+
 #ifndef GST_DISABLE_LOADSAVE
 void			gst_pad_load_and_link			(xmlNodePtr self, GstObject *parent);
 #endif

win32/common/libgstreamer.def

@@ -612,6 +612,7 @@ EXPORTS
 	gst_pad_is_blocked
 	gst_pad_is_blocking
 	gst_pad_is_linked
+	gst_pad_is_negotiable
 	gst_pad_iterate_internal_links
 	gst_pad_iterate_internal_links_default
 	gst_pad_link
@@ -665,6 +666,7 @@ EXPORTS
 	gst_pad_set_internal_link_function
 	gst_pad_set_iterate_internal_links_function
 	gst_pad_set_link_function
+	gst_pad_set_negotiable
 	gst_pad_set_query_function
 	gst_pad_set_query_type_function
 	gst_pad_set_setcaps_function