element: Enforce that elements created by gst_element_factory_create/make() are floating

[platform/upstream/gstreamer.git] / gst / gstcontext.c

diff --git a/gst/gstcontext.c b/gst/gstcontext.c
index 359526b..c1bbe0a 100644 (file)
--- a/gst/gstcontext.c
+++ b/gst/gstcontext.c
@@ -23,6 +23,7 @@
 
 /**
  * SECTION:gstcontext
+ * @title: GstContext
  * @short_description: Lightweight objects to represent element contexts
  * @see_also: #GstMiniObject, #GstElement
  *
@@ -32,23 +33,29 @@
  *
  * Applications can set a context on a complete pipeline by using
  * gst_element_set_context(), which will then be propagated to all
- * child elements. Elements can handle these in GstElement::set_context()
+ * child elements. Elements can handle these in #GstElementClass.set_context()
  * and merge them with the context information they already have.
  *
  * When an element needs a context it will do the following actions in this
  * order until one step succeeds:
- * 1) Check if the element already has a context
- * 2) Query downstream with GST_QUERY_CONTEXT for the context
- * 2) Query upstream with GST_QUERY_CONTEXT for the context
- * 3) Post a GST_MESSAGE_NEED_CONTEXT message on the bus with the required
+ * 1. Check if the element already has a context
+ * 2. Query downstream with GST_QUERY_CONTEXT for the context
+ * 3. Query upstream with GST_QUERY_CONTEXT for the context
+ * 4. Post a GST_MESSAGE_NEED_CONTEXT message on the bus with the required
  *    context types and afterwards check if a usable context was set now
- * 4) Create a context by itself and post a GST_MESSAGE_HAVE_CONTEXT message
+ * 5. Create a context by itself and post a GST_MESSAGE_HAVE_CONTEXT message
  *    on the bus.
  *
  * Bins will catch GST_MESSAGE_NEED_CONTEXT messages and will set any previously
  * known context on the element that asks for it if possible. Otherwise the
  * application should provide one if it can.
  *
+ * #GstContext<!-- -->s can be persistent.
+ * A persistent #GstContext is kept in elements when they reach
+ * %GST_STATE_NULL, non-persistent ones will be removed.
+ * Also, a non-persistent context won't override a previous persistent
+ * context set to an element.
+ *
  * Since: 1.2
  */
 
@@ -68,7 +75,7 @@ struct _GstContext
 
 #define GST_CONTEXT_STRUCTURE(c)  (((GstContext *)(c))->structure)
 
-static GType _gst_context_type = 0;
+GType _gst_context_type = 0;
 GST_DEFINE_MINI_OBJECT_TYPE (GstContext, gst_context);
 
 void
@@ -101,6 +108,10 @@ _gst_context_free (GstContext * context)
   }
   g_free (context->context_type);
 
+#ifdef USE_POISONING
+  memset (context, 0xff, sizeof (GstContext));
+#endif
+
   g_slice_free1 (sizeof (GstContext), context);
 }
 
@@ -141,6 +152,7 @@ gst_context_init (GstContext * context)
 
 /**
  * gst_context_new:
+ * @context_type: Context type
  * @persistent: Persistent context
  *
  * Create a new context.
@@ -191,6 +203,27 @@ gst_context_get_context_type (const GstContext * context)
 }
 
 /**
+ * gst_context_has_context_type:
+ * @context: The #GstContext.
+ * @context_type: Context type to check.
+ *
+ * Checks if @context has @context_type.
+ *
+ * Returns: %TRUE if @context has @context_type.
+ *
+ * Since: 1.2
+ */
+gboolean
+gst_context_has_context_type (const GstContext * context,
+    const gchar * context_type)
+{
+  g_return_val_if_fail (GST_IS_CONTEXT (context), FALSE);
+  g_return_val_if_fail (context_type != NULL, FALSE);
+
+  return strcmp (context->context_type, context_type) == 0;
+}
+
+/**
  * gst_context_get_structure:
  * @context: The #GstContext.
  *
@@ -217,8 +250,8 @@ gst_context_get_structure (const GstContext * context)
  * Get a writable version of the structure.
  *
  * Returns: The structure of the context. The structure is still
- * owned by the event, which means that you should not free it and
- * that the pointer becomes invalid when you free the event.
+ * owned by the context, which means that you should not free it and
+ * that the pointer becomes invalid when you free the context.
  * This function checks if @context is writable.
  *
  * Since: 1.2
@@ -245,7 +278,7 @@ gst_context_writable_structure (GstContext * context)
 gboolean
 gst_context_is_persistent (const GstContext * context)
 {
-  g_return_val_if_fail (GST_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (GST_IS_CONTEXT (context), FALSE);
 
   return context->persistent;
 }