gapi: Full calcOpticalFlowPyrLK implementation (2 overloads) and tests

- opencv_gapi module is linked with opencv_video module (optional dependency)
     - kernels added to a new cv::gapi::video namespace and a brand new files created to provide gapi_video environment
     - there are 2 different kernels as G-API should provide GMat AND GArray<GMat> implementation: cv::calcOptFlowPyrLK doesn't calculate pyramids if vector<Mat> is given so just the cast GMat -> GArray<GMat> wouldn't represent all the cv:: functionality
     - tests to check both kernels (based on cv::video tests for cv::calcOpticalFlowPyrLK())
     - tests for internal purposes added
     - vectors<T> comparison in tests implemented
     - new (and old too) common test structures refactored to avoid code copypasting
     - "modules/gapi/test/common/gapi_video_tests_common.hpp" created to share some code snippets between perf and acc tests and avoid code copypasting

modules/gapi/perf/common/gapi_imgproc_perf_tests.hpp

@@ -49,5 +49,6 @@ class YUV2BGRPerfTest : public TestPerfParams<tuple<compare_f, cv::Size, cv::GCo
 class RGB2HSVPerfTest : public TestPerfParams<tuple<compare_f, cv::Size, cv::GCompileArgs>> {};
 class BayerGR2RGBPerfTest : public TestPerfParams<tuple<compare_f, cv::Size, cv::GCompileArgs>> {};
 class RGB2YUV422PerfTest  : public TestPerfParams<tuple<compare_f, cv::Size, cv::GCompileArgs>> {};
-}
+} // opencv_test
+
 #endif //OPENCV_GAPI_IMGPROC_PERF_TESTS_HPP

modules/gapi/perf/common/gapi_video_perf_tests.cpp

@@ -0,0 +1,9 @@
+// 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
+
+
+#include "../perf_precomp.hpp"
+#include "gapi_video_perf_tests_inl.hpp"

modules/gapi/perf/common/gapi_video_perf_tests.hpp

@@ -0,0 +1,26 @@
+// 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_VIDEO_PERF_TESTS_HPP
+#define OPENCV_GAPI_VIDEO_PERF_TESTS_HPP
+
+#include "../../test/common/gapi_video_tests_common.hpp"
+
+namespace opencv_test
+{
+
+using namespace perf;
+
+//------------------------------------------------------------------------------
+
+class OptFlowLKPerfTest : public TestPerfParams<tuple<std::string,int,tuple<int,int>,int,
+                                                      cv::TermCriteria,cv::GCompileArgs>> {};
+class OptFlowLKForPyrPerfTest : public TestPerfParams<tuple<std::string,int,tuple<int,int>,int,
+                                                            cv::TermCriteria,bool,
+                                                            cv::GCompileArgs>> {};
+} // opencv_test
+
+#endif // OPENCV_GAPI_VIDEO_PERF_TESTS_HPP

modules/gapi/perf/common/gapi_video_perf_tests_inl.hpp

@@ -0,0 +1,90 @@
+// 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_VIDEO_PERF_TESTS_INL_HPP
+#define OPENCV_GAPI_VIDEO_PERF_TESTS_INL_HPP
+
+#include <iostream>
+
+#include "gapi_video_perf_tests.hpp"
+
+namespace opencv_test
+{
+
+  using namespace perf;
+
+//------------------------------------------------------------------------------
+
+PERF_TEST_P_(OptFlowLKPerfTest, TestPerformance)
+{
+    std::vector<cv::Point2f> outPtsOCV,    outPtsGAPI,    inPts;
+    std::vector<uchar>       outStatusOCV, outStatusGAPI;
+    std::vector<float>       outErrOCV,    outErrGAPI;
+
+    OptFlowLKTestParams params;
+    std::tie(params.fileNamePattern, params.channels,
+             params.pointsNum, params.winSize, params.criteria,
+             params.compileArgs) = GetParam();
+
+    OptFlowLKTestOutput outOCV  { outPtsOCV,  outStatusOCV,  outErrOCV };
+    OptFlowLKTestOutput outGAPI { outPtsGAPI, outStatusGAPI, outErrGAPI };
+
+    cv::GComputation c = runOCVnGAPIOptFlowLK(*this, inPts, params, outOCV, outGAPI);
+
+    declare.in(in_mat1, in_mat2, inPts).out(outPtsGAPI, outStatusGAPI, outErrGAPI);
+
+    TEST_CYCLE()
+    {
+        c.apply(cv::gin(in_mat1, in_mat2, inPts, std::vector<cv::Point2f>{ }),
+                cv::gout(outPtsGAPI, outStatusGAPI, outErrGAPI));
+    }
+
+    // Comparison //////////////////////////////////////////////////////////////
+    compareOutputsOptFlow(outOCV, outGAPI);
+
+    SANITY_CHECK_NOTHING();
+}
+
+//------------------------------------------------------------------------------
+
+PERF_TEST_P_(OptFlowLKForPyrPerfTest, TestPerformance)
+{
+    std::vector<cv::Mat>     inPyr1, inPyr2;
+    std::vector<cv::Point2f> outPtsOCV,    outPtsGAPI,    inPts;
+    std::vector<uchar>       outStatusOCV, outStatusGAPI;
+    std::vector<float>       outErrOCV,    outErrGAPI;
+
+    bool withDeriv = false;
+    OptFlowLKTestParams params;
+    std::tie(params.fileNamePattern, params.channels,
+             params.pointsNum, params.winSize, params.criteria,
+             withDeriv, params.compileArgs) = GetParam();
+
+    OptFlowLKTestInput<std::vector<cv::Mat>> in { inPyr1, inPyr2, inPts };
+    OptFlowLKTestOutput outOCV  { outPtsOCV,  outStatusOCV,  outErrOCV };
+    OptFlowLKTestOutput outGAPI { outPtsGAPI, outStatusGAPI, outErrGAPI };
+
+    cv::GComputation c = runOCVnGAPIOptFlowLKForPyr(*this, in, params, withDeriv, outOCV, outGAPI);
+
+    declare.in(inPyr1, inPyr2, inPts).out(outPtsGAPI, outStatusGAPI, outErrGAPI);
+
+    TEST_CYCLE()
+    {
+        c.apply(cv::gin(inPyr1, inPyr2, inPts, std::vector<cv::Point2f>{ }),
+                cv::gout(outPtsGAPI, outStatusGAPI, outErrGAPI));
+    }
+
+    // Comparison //////////////////////////////////////////////////////////////
+    compareOutputsOptFlow(outOCV, outGAPI);
+
+    SANITY_CHECK_NOTHING();
+}
+
+//------------------------------------------------------------------------------
+
+} // opencv_test
+
+#endif // OPENCV_GAPI_VIDEO_PERF_TESTS_INL_HPP