Implement python backend

modules/gapi/include/opencv2/gapi/core.hpp

@@ -645,7 +645,7 @@ Supported matrix data types are @ref CV_8UC1, @ref CV_8UC3, @ref CV_16UC1, @ref
 @param ddepth optional depth of the output matrix.
 @sa sub, addWeighted
 */
-GAPI_EXPORTS GMat addC(const GMat& src1, const GScalar& c, int ddepth = -1);
+GAPI_EXPORTS_W GMat addC(const GMat& src1, const GScalar& c, int ddepth = -1);
 //! @overload
 GAPI_EXPORTS GMat addC(const GScalar& c, const GMat& src1, int ddepth = -1);
 
@@ -1945,7 +1945,7 @@ Gets dimensions from rectangle.
 @param r Input rectangle.
 @return Size (rectangle dimensions).
 */
-GAPI_EXPORTS GOpaque<Size> size(const GOpaque<Rect>& r);
+GAPI_EXPORTS_W GOpaque<Size> size(const GOpaque<Rect>& r);
 
 /** @brief Gets dimensions from MediaFrame.
 

modules/gapi/include/opencv2/gapi/imgproc.hpp

@@ -1168,7 +1168,7 @@ Calculates the up-right bounding rectangle of a point set.
 
 @param src Input 2D point set, stored in std::vector<cv::Point2i>.
  */
-GAPI_EXPORTS GOpaque<Rect> boundingRect(const GArray<Point2i>& src);
+GAPI_EXPORTS_W GOpaque<Rect> boundingRect(const GArray<Point2i>& src);
 
 /** @overload
 

modules/gapi/include/opencv2/gapi/python/python.hpp

@@ -0,0 +1,58 @@
+// 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) 2021 Intel Corporation
+
+
+#ifndef OPENCV_GAPI_PYTHON_API_HPP
+#define OPENCV_GAPI_PYTHON_API_HPP
+
+#include <opencv2/gapi/gkernel.hpp>     // GKernelPackage
+#include <opencv2/gapi/own/exports.hpp> // GAPI_EXPORTS
+
+namespace cv {
+namespace gapi {
+namespace python {
+
+GAPI_EXPORTS cv::gapi::GBackend backend();
+
+struct GPythonContext
+{
+    const cv::GArgs      &ins;
+    const cv::GMetaArgs  &in_metas;
+    const cv::GTypesInfo &out_info;
+};
+
+using Impl = std::function<cv::GRunArgs(const GPythonContext&)>;
+
+class GAPI_EXPORTS GPythonKernel
+{
+public:
+    GPythonKernel() = default;
+    GPythonKernel(Impl run);
+
+    cv::GRunArgs operator()(const GPythonContext& ctx);
+private:
+    Impl m_run;
+};
+
+class GAPI_EXPORTS GPythonFunctor : public cv::gapi::GFunctor
+{
+public:
+    using Meta = cv::GKernel::M;
+
+    GPythonFunctor(const char* id, const Meta &meta, const Impl& impl);
+
+    GKernelImpl    impl()    const override;
+    gapi::GBackend backend() const override;
+
+private:
+    GKernelImpl impl_;
+};
+
+} // namespace python
+} // namespace gapi
+} // namespace cv
+
+#endif // OPENCV_GAPI_PYTHON_API_HPP