overrides: add a set_caps() method to the Pad override

The C API provides the gst_pad_set_caps() helper which makes it easier
to set caps on pads (see gst/gstcompat.h in gstreamer core).

Add such handy helper to the python bindings too.

The implementation follows as close as possible the one in gstcompat.h
with two changes:
  1. the type check on the pad has been removed because self is
     guaranteed to be a Gst.Pad in python.
  2. the null check on the caps has been extended to be a type check.

Fixes https://gitlab.freedesktop.org/gstreamer/gst-python/issues/19

diff --git a/gi/overrides/Gst.py b/gi/overrides/Gst.py
index 2e5189b..499e82f 100644 (file)
--- a/gi/overrides/Gst.py
+++ b/gi/overrides/Gst.py
@@ -156,6 +156,22 @@ class Pad(Gst.Pad):
     def query_caps(self, filter=None):
         return Gst.Pad.query_caps(self, filter)
 
+    def set_caps(self, caps):
+        if not isinstance(caps, Gst.Caps):
+            raise TypeError("%s is not a Gst.Caps." % (type(caps)))
+
+        if not caps.is_fixed():
+            return False
+
+        event = Gst.Event.new_caps(caps)
+
+        if self.direction == Gst.PadDirection.SRC:
+            res = self.push_event(event)
+        else:
+            res = self.send_event(event)
+
+        return res
+
     def link(self, pad):
         ret = Gst.Pad.link(self, pad)
         if ret != Gst.PadLinkReturn.OK: