Implement asynchronous execution for islands

modules/gapi/src/api/gproto.cpp

@@ -264,4 +264,28 @@ std::ostream& operator<<(std::ostream& os, const cv::GMetaArg &arg)
 
     return os;
 }
+} // namespace cv
+
+// TODO: This function requires thorough testing
+const void* cv::gimpl::proto::ptr(const GRunArgP &arg)
+{
+    switch (arg.index())
+    {
+#if !defined(GAPI_STANDALONE)
+    case GRunArgP::index_of<cv::Mat*>():
+        return static_cast<const void*>(cv::util::get<cv::Mat*>(arg));
+    case GRunArgP::index_of<cv::Scalar*>():
+        return static_cast<const void*>(cv::util::get<cv::Scalar*>(arg));
+    case GRunArgP::index_of<cv::UMat*>():
+        return static_cast<const void*>(cv::util::get<cv::UMat*>(arg));
+#endif
+    case GRunArgP::index_of<cv::gapi::own::Mat*>():
+        return static_cast<const void*>(cv::util::get<cv::gapi::own::Mat*>(arg));
+    case GRunArgP::index_of<cv::detail::VectorRef>():
+        return cv::util::get<cv::detail::VectorRef>(arg).ptr();
+    case GRunArgP::index_of<cv::detail::OpaqueRef>():
+        return cv::util::get<cv::detail::OpaqueRef>(arg).ptr();
+    default:
+        util::throw_error(std::logic_error("Unknown GRunArgP type!"));
+    }
 }

modules/gapi/src/api/gproto_priv.hpp

@@ -28,8 +28,13 @@ GAPI_EXPORTS const GOrigin& origin_of (const GArg      &arg);
 bool           is_dynamic(const GArg      &arg);
 GProtoArg      rewrap    (const GArg      &arg);
 
+const void*    ptr       (const GRunArgP  &arg);
+
 } // proto
 } // gimpl
 } // cv
 
+// FIXME: the gproto.cpp file has more functions that listed here
+// where those are declared??
+
 #endif // OPENCV_GAPI_GPROTO_PRIV_HPP