[pitivi] utils: Add a method to get the controllable properties of a GstObject

[Edward Hervey <edwardrv src gnome org>]

commit 146458345f6aef42286b10ab12bcf879653a56df
Author: Edward Hervey <bilboed bilboed com>
Date:   Fri Jun 12 13:10:09 2009 +0200

    utils: Add a method to get the controllable properties of a GstObject
    
    Will recursively go down into the childs.

 pitivi/utils.py |   21 +++++++++++++++++++++
 1 files changed, 21 insertions(+), 0 deletions(-)
---
diff --git a/pitivi/utils.py b/pitivi/utils.py
index ba03c99..4928743 100644
--- a/pitivi/utils.py
+++ b/pitivi/utils.py
@@ -304,3 +304,24 @@ class Seeker(Signallable):
 
 def get_filesystem_encoding():
     return sys.getfilesystemencoding() or "utf-8"
+
+def get_controllable_properties(element):
+    """
+    Returns a list of controllable properties for the given
+    element (and child if it's a container).
+
+    The list is made of tuples containing:
+    * The GstObject
+    * The GParamspec
+    """
+    log.debug("utils", "element %r, %d", element, isinstance(element, gst.Bin))
+    res = []
+    if isinstance(element, gst.Bin):
+        for child in element.elements():
+            res.extend(get_controllable_properties(child))
+    else:
+        for prop in gobject.list_properties(element):
+            if prop.flags & gst.PARAM_CONTROLLABLE:
+                log.debug("utils", "adding property %r", prop)
+                res.append((element, prop))
+    return res