Merge pull request #18493 from TolyaTalamanov:at/wrap-streaming

[G-API Wrap streaming

* Wrap streaming

* Fix build

* Add comments

* Remove comment

* Fix comments to review

* Add test for python pull overload

modules/gapi/src/compiler/gcompiler.cpp

@@ -448,6 +448,14 @@ cv::GStreamingCompiled cv::gimpl::GCompiler::produceStreamingCompiled(GPtr &&pg)
         outMetas = GModel::ConstGraph(*pg).metadata().get<OutputMeta>().outMeta;
     }
 
+    auto out_desc = GModel::ConstGraph(*pg).metadata().get<cv::gimpl::Protocol>().outputs;
+    GShapes out_shapes;
+    for (auto&& desc : out_desc)
+    {
+        out_shapes.push_back(desc.shape);
+    }
+    compiled.priv().setOutShapes(std::move(out_shapes));
+
     std::unique_ptr<GStreamingExecutor> pE(new GStreamingExecutor(std::move(pg),
                                                                   m_args));
     if (!m_metas.empty() && !outMetas.empty())

modules/gapi/src/compiler/gstreaming.cpp

@@ -111,6 +111,39 @@ bool cv::GStreamingCompiled::pull(cv::GRunArgsP &&outs)
     return m_priv->pull(std::move(outs));
 }
 
+std::tuple<bool, cv::GRunArgs> cv::GStreamingCompiled::pull()
+{
+    GRunArgs run_args;
+    GRunArgsP outs;
+    const auto& out_shapes = m_priv->outShapes();
+    run_args.reserve(out_shapes.size());
+    outs.reserve(out_shapes.size());
+
+    for (auto&& shape : out_shapes)
+    {
+        switch (shape)
+        {
+            case cv::GShape::GMAT:
+            {
+                run_args.emplace_back(cv::Mat{});
+                outs.emplace_back(&cv::util::get<cv::Mat>(run_args.back()));
+                break;
+            }
+            case cv::GShape::GSCALAR:
+            {
+                run_args.emplace_back(cv::Scalar{});
+                outs.emplace_back(&cv::util::get<cv::Scalar>(run_args.back()));
+                break;
+            }
+            default:
+                util::throw_error(std::logic_error("Only cv::GMat and cv::GScalar are supported for python output"));
+        }
+    }
+
+    bool is_over = m_priv->pull(std::move(outs));
+    return std::make_tuple(is_over, run_args);
+}
+
 bool cv::GStreamingCompiled::try_pull(cv::GRunArgsP &&outs)
 {
     return m_priv->try_pull(std::move(outs));

modules/gapi/src/compiler/gstreaming_priv.hpp

@@ -27,6 +27,7 @@ class GAPI_EXPORTS GStreamingCompiled::Priv
     GMetaArgs  m_metas;    // passed by user
     GMetaArgs  m_outMetas; // inferred by compiler
     std::unique_ptr<cv::gimpl::GStreamingExecutor> m_exec;
+    GShapes m_out_shapes;
 
 public:
     void setup(const GMetaArgs &metaArgs,
@@ -45,6 +46,11 @@ public:
     void stop();
 
     bool running() const;
+
+    // NB: std::tuple<bool, cv::GRunArgs> pull() creates GRunArgs for outputs,
+    // so need to know out shapes to create corresponding GRunArg
+    void setOutShapes(GShapes shapes) { m_out_shapes = std::move(shapes); }
+    const GShapes& outShapes() const { return m_out_shapes; }
 };
 
 } // namespace cv