Merge pull request #18415 from dmatveev:dm/gframe_01_new_host_type

* G-API: Introduce cv::MediaFrame, a host type for cv::GFrame

* G-API: RMat -- address review comments

modules/gapi/include/opencv2/gapi.hpp

@@ -24,6 +24,9 @@
 
 #include <opencv2/gapi/gmat.hpp>
 #include <opencv2/gapi/garray.hpp>
+#include <opencv2/gapi/gscalar.hpp>
+#include <opencv2/gapi/gopaque.hpp>
+#include <opencv2/gapi/gframe.hpp>
 #include <opencv2/gapi/gcomputation.hpp>
 #include <opencv2/gapi/gcompiled.hpp>
 #include <opencv2/gapi/gtyped.hpp>

modules/gapi/include/opencv2/gapi/gframe.hpp

@@ -42,12 +42,20 @@ private:
 };
 /** @} */
 
+enum class MediaFormat
+{
+    BGR = 0,
+    NV12,
+};
+
 /**
  * \addtogroup gapi_meta_args
  * @{
  */
 struct GAPI_EXPORTS GFrameDesc
 {
+    MediaFormat fmt;
+    cv::Size size;
 };
 static inline GFrameDesc empty_gframe_desc() { return GFrameDesc{}; }
 /** @} */

modules/gapi/include/opencv2/gapi/media.hpp

@@ -0,0 +1,72 @@
+// This file is part of OpenCV project.
+// It is subject to the license terms in the LICENSE file found in the top-level directory
+// of this distribution and at http://opencv.org/license.html.
+//
+// Copyright (C) 2020 Intel Corporation
+
+#ifndef OPENCV_GAPI_MEDIA_HPP
+#define OPENCV_GAPI_MEDIA_HPP
+
+#include <memory>     // unique_ptr<>, shared_ptr<>
+#include <array>      // array<>
+#include <functional> // function<>
+#include <utility>    // forward<>()
+
+#include <opencv2/gapi/gframe.hpp>
+
+namespace cv {
+
+class GAPI_EXPORTS MediaFrame {
+public:
+    enum class Access { R, W };
+    class IAdapter;
+    class View;
+    using AdapterPtr = std::unique_ptr<IAdapter>;
+
+    MediaFrame();
+    explicit MediaFrame(AdapterPtr &&);
+    template<class T, class... Args> static cv::MediaFrame Create(Args&&...);
+
+    View access(Access);
+    cv::GFrameDesc desc() const;
+
+private:
+    struct Priv;
+    std::shared_ptr<Priv> m;
+};
+
+template<class T, class... Args>
+inline cv::MediaFrame cv::MediaFrame::Create(Args&&... args) {
+    std::unique_ptr<T> ptr(new T(std::forward<Args>(args)...));
+    return cv::MediaFrame(std::move(ptr));
+}
+
+class GAPI_EXPORTS MediaFrame::View final {
+public:
+    static constexpr const size_t MAX_PLANES = 4;
+    using Ptrs     = std::array<void*, MAX_PLANES>;
+    using Strides  = std::array<std::size_t, MAX_PLANES>; // in bytes
+    using Callback = std::function<void()>;
+
+    View(Ptrs&& ptrs, Strides&& strs, Callback &&cb = [](){});
+    View(const View&) = delete;
+    View(View&&) = default;
+    ~View();
+
+    Ptrs    ptr;
+    Strides stride;
+
+private:
+    Callback m_cb;
+};
+
+class GAPI_EXPORTS MediaFrame::IAdapter {
+public:
+    virtual ~IAdapter() = 0;
+    virtual cv::GFrameDesc meta() const = 0;
+    virtual MediaFrame::View access(MediaFrame::Access) = 0;
+};
+
+} //namespace cv
+
+#endif // OPENCV_GAPI_MEDIA_HPP