/* GStreamer
* Copyright (C) 2013 Collabora Ltd.
* Author: Sebastian Dröge <sebastian.droege@collabora.co.uk>
+ * Copyright (C) 2013 Sebastian Dröge <slomo@circular-chaos.org>
*
* gstcontext.h: Header for GstContext subsystem
*
/**
* SECTION:gstcontext
+ * @title: GstContext
* @short_description: Lightweight objects to represent element contexts
* @see_also: #GstMiniObject, #GstElement
*
*
* 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
- * 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
- * and send a GST_EVENT_CONTEXT event downstream, containing the complete
- * context information at this time.
+ * 5. Create a context by itself and post a GST_MESSAGE_HAVE_CONTEXT message
+ * on the bus.
*
- * Applications should catch the GST_MESSAGE_HAVE_CONTEXT messages and remember
- * any content from it unless it has a custom version of a specific context. If
- * later an element is posting a GST_MESSAGE_NEED_CONTEXT message for a specific
- * context that was created by an element before, the application should pass it
- * to the element or the complete pipeline.
+ * 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
*/
{
GstMiniObject mini_object;
+ gchar *context_type;
GstStructure *structure;
+ gboolean persistent;
};
#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
gst_structure_set_parent_refcount (structure, NULL);
gst_structure_free (structure);
}
+ g_free (context->context_type);
+
+#ifdef USE_POISONING
+ memset (context, 0xff, sizeof (GstContext));
+#endif
g_slice_free1 (sizeof (GstContext), context);
}
gst_context_init (copy);
+ copy->context_type = g_strdup (context->context_type);
+
structure = GST_CONTEXT_STRUCTURE (context);
GST_CONTEXT_STRUCTURE (copy) = gst_structure_copy (structure);
gst_structure_set_parent_refcount (GST_CONTEXT_STRUCTURE (copy),
©->mini_object.refcount);
+ copy->persistent = context->persistent;
+
return GST_CONTEXT_CAST (copy);
}
/**
* gst_context_new:
+ * @context_type: Context type
+ * @persistent: Persistent context
*
* Create a new context.
*
* Since: 1.2
*/
GstContext *
-gst_context_new (void)
+gst_context_new (const gchar * context_type, gboolean persistent)
{
GstContext *context;
GstStructure *structure;
+ g_return_val_if_fail (context_type != NULL, NULL);
+
context = g_slice_new0 (GstContext);
GST_CAT_LOG (GST_CAT_CONTEXT, "creating new context %p", context);
gst_structure_set_parent_refcount (structure, &context->mini_object.refcount);
gst_context_init (context);
+ context->context_type = g_strdup (context_type);
GST_CONTEXT_STRUCTURE (context) = structure;
+ context->persistent = persistent;
return context;
}
/**
+ * gst_context_get_context_type:
+ * @context: The #GstContext.
+ *
+ * Get the type of @context.
+ *
+ * Returns: The type of the context.
+ *
+ * Since: 1.2
+ */
+const gchar *
+gst_context_get_context_type (const GstContext * context)
+{
+ g_return_val_if_fail (GST_IS_CONTEXT (context), NULL);
+
+ return context->context_type;
+}
+
+/**
+ * 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.
*
* Since: 1.2
*/
const GstStructure *
-gst_context_get_structure (GstContext * context)
+gst_context_get_structure (const GstContext * context)
{
g_return_val_if_fail (GST_IS_CONTEXT (context), NULL);
* 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
return GST_CONTEXT_STRUCTURE (context);
}
+
+/**
+ * gst_context_is_persistent:
+ * @context: The #GstContext.
+ *
+ * Check if @context is persistent.
+ *
+ * Returns: %TRUE if the context is persistent.
+ *
+ * Since: 1.2
+ */
+gboolean
+gst_context_is_persistent (const GstContext * context)
+{
+ g_return_val_if_fail (GST_IS_CONTEXT (context), FALSE);
+
+ return context->persistent;
+}
projects / platform / upstream / gstreamer.git / blobdiff