Subclass Exception for mapping and unmapping errors

And minor cleanup in the way errors are handled

examples/plugins/python/exampleTransform.py

@@ -38,12 +38,16 @@ class ExampleTransform(GstBase.BaseTransform):
         return True
 
     def do_transform_ip(self, buf):
-        with buf.map(Gst.MapFlags.READ | Gst.MapFlags.WRITE) as info:
-            # Create a NumPy ndarray from the memoryview and modify it in place:
-            A = np.ndarray(shape = (self.height, self.width), dtype = np.uint8, buffer = info.data)
-            A[:] = np.invert(A)
+        try:
+            with buf.map(Gst.MapFlags.READ | Gst.MapFlags.WRITE) as info:
+                # Create a NumPy ndarray from the memoryview and modify it in place:
+                A = np.ndarray(shape = (self.height, self.width), dtype = np.uint8, buffer = info.data)
+                A[:] = np.invert(A)
 
-            return Gst.FlowReturn.OK
+                return Gst.FlowReturn.OK
+        except Gst.MapError as e:
+            Gst.error("Mapping error: %s" % e)
+            return Gst.FlowReturn.ERROR
 
 GObject.type_register(ExampleTransform)
 __gstelementfactory__ = ("ExampleTransform", Gst.Rank.NONE, ExampleTransform)

gi/overrides/Gst.py

@@ -225,6 +225,11 @@ class LinkError(Exception):
     pass
 __all__.append('LinkError')
 
+class MapError(Exception):
+    pass
+__all__.append('MapError')
+
+
 class Iterator(Gst.Iterator):
     def __iter__(self):
         while True:
@@ -612,23 +617,22 @@ __all__.append("MapInfo")
 class Buffer(Gst.Buffer):
 
     def map_range(self, idx, length, flags):
-        mapinfo = MapInfo() 
+        mapinfo = MapInfo()
         if (_gi_gst.buffer_override_map_range(self, mapinfo, idx, length, int(flags))):
             mapinfo.__parent__ = self
             return (mapinfo)
-        raise Exception('MappingError','Buffer mapping was not successfull')
-        return None
+        raise MapError('MappingError','Buffer mapping was not successfull')
 
     def map(self, flags):
         mapinfo = MapInfo()
-        if (_gi_gst.buffer_override_map(self, mapinfo, int(flags))):
+        if _gi_gst.buffer_override_map(self, mapinfo, int(flags)):
             mapinfo.__parent__ = self
-            return (mapinfo)
-        raise Exception('MappingError','Buffer mapping was not successfull')
-        return None
+            return mapinfo
+        raise MapError('MappingError','Buffer mapping was not successfull')
 
     def unmap(self, mapinfo):
-        _gi_gst.buffer_override_unmap(self, mapinfo)
+        if _gi_gst.buffer_override_unmap(self, mapinfo) is not True:
+            raise MapError('UnmappingError','Buffer unmapping was not successfull')
 
 Buffer = override(Buffer)
 __all__.append('Buffer')
@@ -640,11 +644,10 @@ class Memory(Gst.Memory):
         if (_gi_gst.memory_override_map(self, mapinfo, int(flags))):
             mapinfo.__parent__ = self
             return (mapinfo)
-        raise Exception('MappingError','Memory mapping was not successfull')
-        return None
+        raise MapError('MappingError','Memory mapping was not successfull')
 
     def unmap(self, mapinfo):
-        _gi_gst.memory_override_unmap(self, mapinfo)
+        return _gi_gst.memory_override_unmap(self, mapinfo)
 
 Memory = override(Memory)
 __all__.append('Memory')

gi/overrides/gstmodule.c

@@ -805,14 +805,18 @@ _gst_memory_override_unmap (PyObject * self, PyObject * args)
 
   /* Look up Gst.Buffer and Gst.Mapinfo parameters */
   gst_memory_type = pygobject_lookup_class (_gst_memory_type);
-  if (!PyArg_ParseTuple (args, "O!O", gst_memory_type, &py_memory, &py_mapinfo))
+  if (!PyArg_ParseTuple (args, "O!O", gst_memory_type, &py_memory, &py_mapinfo)) {
+    PyErr_BadArgument ();
     return NULL;
+  }
 
   /* Extract attributes from Gst.MapInfo */
   if (!(mview = PyObject_GetAttrString (py_mapinfo, "data")))
     goto err;
+
   if (!PyObject_HasAttrString (py_mapinfo, "__cmapinfo"))
     goto end;
+
   if (!(py_cmapinfo = PyObject_GetAttrString (py_mapinfo, "__cmapinfo")))
     goto err;
 
@@ -835,10 +839,10 @@ _gst_memory_override_unmap (PyObject * self, PyObject * args)
   g_free (mapinfo);
 end:
   Py_DECREF (mview);
-  Py_RETURN_NONE;
+  return Py_True;
 
 err:
-  return NULL;
+  return Py_False;
 }
 
 static PyObject *
@@ -856,7 +860,7 @@ _gst_buffer_override_map_range (PyObject * self, PyObject * args)
   gst_buffer_type = pygobject_lookup_class (_gst_buffer_type);
   if (!PyArg_ParseTuple (args, "O!OIii", gst_buffer_type, &py_buffer,
           &py_mapinfo, &idx, &range, &flags))
-    return NULL;
+    return Py_False;
 
   /* Since Python does only support r/o or r/w it has to be changed to either */
   flags = (flags & GST_MAP_WRITE) ? GST_MAP_READWRITE : GST_MAP_READ;
@@ -893,8 +897,10 @@ _gst_buffer_override_map (PyObject * self, PyObject * args)
   /* Look up Gst.Buffer, Gst.MapInfo, and Gst.MapFlags parameters */
   gst_buffer_type = pygobject_lookup_class (_gst_buffer_type);
   if (!PyArg_ParseTuple (args, "O!Oi", gst_buffer_type, &py_buffer, &py_mapinfo,
-          &flags))
+          &flags)) {
+    PyErr_BadArgument ();
     return NULL;
+  }
 
   /* Since Python does only support r/o or r/w it has to be changed to either */
   flags = (flags & GST_MAP_WRITE) ? GST_MAP_READWRITE : GST_MAP_READ;
@@ -928,14 +934,18 @@ _gst_buffer_override_unmap (PyObject * self, PyObject * args)
 
   /* Look up Gst.Buffer and Gst.Mapinfo parameters */
   gst_buf_type = pygobject_lookup_class (_gst_buffer_type);
-  if (!PyArg_ParseTuple (args, "O!O", gst_buf_type, &py_buffer, &py_mapinfo))
+  if (!PyArg_ParseTuple (args, "O!O", gst_buf_type, &py_buffer, &py_mapinfo)) {
+    PyErr_BadArgument ();
     return NULL;
+  }
 
   /* Extract attributes from Gst.MapInfo */
   if (!(mview = PyObject_GetAttrString (py_mapinfo, "data")))
     goto err;
+
   if (!PyObject_HasAttrString (py_mapinfo, "__cmapinfo"))
     goto end;
+
   if (!(py_cmapinfo = PyObject_GetAttrString (py_mapinfo, "__cmapinfo")))
     goto err;
 
@@ -946,8 +956,11 @@ _gst_buffer_override_unmap (PyObject * self, PyObject * args)
 
   /* Call the memoryview.release() Python method, there is no C API */
   PyObject *ret = PyObject_CallMethod (mview, "release", NULL);
-  if (!ret)
+  if (!ret) {
+    GST_ERROR ("Could not call `.release()` on the memoryview.");
+
     goto err;
+  }
   Py_DECREF (ret);
   Py_DECREF (py_cmapinfo);
   PyObject_SetAttrString (py_mapinfo, "__cmapinfo", NULL);
@@ -957,10 +970,10 @@ _gst_buffer_override_unmap (PyObject * self, PyObject * args)
   g_free (mapinfo);
 end:
   Py_DECREF (mview);
-  Py_RETURN_NONE;
+  return Py_True;
 
 err:
-  return NULL;
+  return Py_False;
 }
 
 static PyMethodDef _gi_gst_functions[] = {