[gstreamermm/devel-other-plugins] Gst::BaseTransform: fix transform_vfunc method

[Marcin Kolny <mkolny src gnome org>]

commit 7730fb3bde9a9dd32b0d2db41ee1e2acc353e1c8
Author: Marcin Kolny <marcin kolny flytronic pl>
Date:   Mon Jul 13 11:07:46 2015 +0200

    Gst::BaseTransform: fix transform_vfunc method
    
        * gstreamer/src/basetransform.{ccg|hg}: transform_vfunc_callback
          increases buffer refcount before passing it to transform_vfunc, but
          some transform* methods require writable buffer.
          transform_vfunc_callback has to be handcrafted, because refcount
          managment isn't trivial in this case.
          It should be done by using std::move and RefPtr move constructor.

 gstreamer/src/basetransform.ccg |   61 +++++++++++++++++++++++++++++++++++++++
 gstreamer/src/basetransform.hg  |    4 ++-
 2 files changed, 64 insertions(+), 1 deletions(-)
---
diff --git a/gstreamer/src/basetransform.ccg b/gstreamer/src/basetransform.ccg
index 9222b41..8d9cdc2 100644
--- a/gstreamer/src/basetransform.ccg
+++ b/gstreamer/src/basetransform.ccg
@@ -100,4 +100,65 @@ Glib::RefPtr<Allocator> BaseTransform::get_allocator(AllocationParams& params)
   return Glib::wrap(alloc, false);
 }
 
+GstFlowReturn BaseTransform_Class::transform_vfunc_callback(GstBaseTransform* self, GstBuffer* inbuf, 
GstBuffer* outbuf)
+{
+  Glib::ObjectBase *const obj_base = static_cast<Glib::ObjectBase*>(
+      Glib::ObjectBase::_get_current_wrapper((GObject*)self));
+
+  if(obj_base && obj_base->is_derived_())
+  {
+    CppObjectType *const obj = dynamic_cast<CppObjectType* const>(obj_base);
+    if(obj) // This can be NULL during destruction.
+    {
+      #ifdef GLIBMM_EXCEPTIONS_ENABLED
+      try // Trap C++ exceptions which would normally be lost because this is a C callback.
+      {
+      #endif //GLIBMM_EXCEPTIONS_ENABLED
+        Glib::RefPtr<Gst::Buffer> w_inbuf = Glib::wrap(inbuf, false),
+            w_outbuf = Glib::wrap(outbuf, false);
+        // Call the virtual member method, which derived classes might override.
+        GstFlowReturn ret = ((GstFlowReturn)(obj->transform_vfunc(w_inbuf, w_outbuf)));
+        w_inbuf->reference(); w_outbuf->reference();
+        return ret;
+      #ifdef GLIBMM_EXCEPTIONS_ENABLED
+      }
+      catch(...)
+      {
+        Glib::exception_handlers_invoke();
+      }
+      #endif //GLIBMM_EXCEPTIONS_ENABLED
+    }
+  }
+
+  BaseClassType *const base = static_cast<BaseClassType*>(
+      g_type_class_peek_parent(G_OBJECT_GET_CLASS(self)) // Get the parent class of the object class (The 
original underlying C class).
+  );
+
+  // Call the original underlying C function:
+  if(base && base->transform)
+  {
+    GstFlowReturn retval = (*base->transform)(self, inbuf, outbuf);
+    return retval;
+  }
+
+  typedef GstFlowReturn RType;
+  return RType();
+}
+
+FlowReturn Gst::BaseTransform::transform_vfunc(const Glib::RefPtr<Gst::Buffer>& inbuf, const 
Glib::RefPtr<Gst::Buffer>& outbuf) 
+{
+  BaseClassType *const base = static_cast<BaseClassType*>(
+      g_type_class_peek_parent(G_OBJECT_GET_CLASS(gobject_)) // Get the parent class of the object class 
(The original underlying C class).
+  );
+
+  if(base && base->transform)
+  {
+    FlowReturn retval(((FlowReturn)((*base->transform)(gobj(),Glib::unwrap(inbuf),Glib::unwrap(outbuf)))));
+    return retval;
+  }
+
+  typedef FlowReturn RType;
+  return RType();
+}
+
 } //namespace Gst
diff --git a/gstreamer/src/basetransform.hg b/gstreamer/src/basetransform.hg
index 7a31f7f..1bb0426 100644
--- a/gstreamer/src/basetransform.hg
+++ b/gstreamer/src/basetransform.hg
@@ -200,7 +200,7 @@ public:
    * incoming buffer to one outgoing buffer. The function is allowed to change
    * size/timestamp/duration of the outgoing buffer.
    */
-  _WRAP_VFUNC(FlowReturn transform(const Glib::RefPtr<Gst::Buffer>& inbuf, const Glib::RefPtr<Gst::Buffer>& 
outbuf), "transform")
+    virtual FlowReturn transform_vfunc(const Glib::RefPtr<Gst::Buffer>& inbuf, const 
Glib::RefPtr<Gst::Buffer>& outbuf);
 
   /** Required if the element operates in-place. Transform the incoming buffer
    * in-place.
@@ -245,8 +245,10 @@ protected:
   klass->start = &start_vfunc_callback;
   klass->stop = &stop_vfunc_callback;
   klass->prepare_output_buffer = &prepare_output_buffer_vfunc_callback;
+  klass->transform = &transform_vfunc_callback;
   _SECTION(SECTION_PH_VFUNCS)
   static GstFlowReturn prepare_output_buffer_vfunc_callback(GstBaseTransform* self, GstBuffer* input, 
GstBuffer** buf);
+  static GstFlowReturn transform_vfunc_callback(GstBaseTransform* self, GstBuffer* inbuf, GstBuffer* outbuf);
   _POP()
 #m4end
 };