Minor s11n and RMat improvements:

 - Changed descr_of(RMat) to use canDescribeHelper to correctly handle planar case
 - Added export of createMat
 - Added setting of Storage::INPUT and Storage::OUTPUT in deserialization routine of GComputation

modules/gapi/src/api/gmat.cpp

@@ -144,7 +144,7 @@ bool GMatDesc::canDescribe(const cv::Mat& mat) const
 
 bool GMatDesc::canDescribe(const cv::RMat& mat) const
 {
-    return *this == mat.desc();
+    return canDescribeHelper(*this, mat);
 }
 
 }// namespace cv

modules/gapi/src/backends/common/gbackend.hpp

@@ -134,7 +134,7 @@ inline cv::util::optional<T> getCompileArg(const cv::GCompileArgs &args)
     return cv::gapi::getCompileArg<T>(args);
 }
 
-void createMat(const cv::GMatDesc& desc, cv::Mat& mat);
+void GAPI_EXPORTS createMat(const cv::GMatDesc& desc, cv::Mat& mat);
 
 }} // cv::gimpl
 

modules/gapi/src/backends/common/serialization.cpp

@@ -94,23 +94,24 @@ void linkNodes(ade::Graph& g) {
 }
 
 void relinkProto(ade::Graph& g) {
+    using namespace cv::gimpl;
     // identify which node handles map to the protocol
     // input/output object in the reconstructed graph
-    using S = std::set<cv::gimpl::RcDesc>;                  // FIXME: use ...
-    using M = std::map<cv::gimpl::RcDesc, ade::NodeHandle>; // FIXME: unordered!
+    using S = std::set<RcDesc>;                  // FIXME: use ...
+    using M = std::map<RcDesc, ade::NodeHandle>; // FIXME: unordered!
 
-    cv::gimpl::GModel::Graph gm(g);
-    auto &proto = gm.metadata().get<cv::gimpl::Protocol>();
+    GModel::Graph gm(g);
+    auto &proto = gm.metadata().get<Protocol>();
 
     const S set_in(proto.inputs.begin(), proto.inputs.end());
     const S set_out(proto.outputs.begin(), proto.outputs.end());
     M map_in, map_out;
 
     // Associate the protocol node handles with their resource identifiers
     for (auto &&nh : gm.nodes()) {
-        if (gm.metadata(nh).get<cv::gimpl::NodeType>().t == cv::gimpl::NodeType::DATA) {
-            const auto &d = gm.metadata(nh).get<cv::gimpl::Data>();
-            const auto rc = cv::gimpl::RcDesc{d.rc, d.shape, d.ctor};
+        if (gm.metadata(nh).get<NodeType>().t == NodeType::DATA) {
+            const auto &d = gm.metadata(nh).get<Data>();
+            const auto rc = RcDesc{d.rc, d.shape, d.ctor};
             if (set_in.count(rc) > 0) {
                 GAPI_DbgAssert(set_out.count(rc) == 0);
                 map_in[rc] = nh;
@@ -128,6 +129,12 @@ void relinkProto(ade::Graph& g) {
     proto.out_nhs.clear();
     for (auto &rc : proto.inputs)  { proto.in_nhs .push_back(map_in .at(rc)); }
     for (auto &rc : proto.outputs) { proto.out_nhs.push_back(map_out.at(rc)); }
+
+    // If a subgraph is being serialized it's possible that
+    // some of its in/out nodes are INTERNAL in the full graph.
+    // Set their storage apporpriately
+    for (auto &nh : proto.in_nhs)  { gm.metadata(nh).get<Data>().storage = Data::Storage::INPUT; }
+    for (auto &nh : proto.out_nhs) { gm.metadata(nh).get<Data>().storage = Data::Storage::OUTPUT; }
 }
 
 } // anonymous namespace