Merge pull request #3827 from asmorkalov:as/gapi_migration

Migrate G-API module from main repo to opencv_contrib #3827

Related to https://github.com/opencv/opencv/pull/26469
Required https://github.com/opencv/opencv/pull/26527
CI: https://github.com/opencv/ci-gha-workflow/pull/201

TODO:
- [x]  Python types generator fix
- [x] CI update

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [ ] The PR is proposed to the proper branch
- [ ] There is a reference to the original bug report and related work
- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [ ] The feature is well documented and sample code can be built with the project CMake

modules/gapi/misc/python/test/test_gapi_imgproc.py

@@ -0,0 +1,127 @@
+#!/usr/bin/env python
+
+import numpy as np
+import cv2 as cv
+import os
+import sys
+import unittest
+
+from tests_common import NewOpenCVTests
+
+
+try:
+
+    if sys.version_info[:2] < (3, 0):
+        raise unittest.SkipTest('Python 2.x is not supported')
+
+    # Plaidml is an optional backend
+    pkgs = [
+               ('ocl'    , cv.gapi.core.ocl.kernels()),
+               ('cpu'    , cv.gapi.core.cpu.kernels()),
+               ('fluid'  , cv.gapi.core.fluid.kernels())
+               # ('plaidml', cv.gapi.core.plaidml.kernels())
+           ]
+
+
+    class gapi_imgproc_test(NewOpenCVTests):
+
+        def test_good_features_to_track(self):
+            # TODO: Extend to use any type and size here
+            img_path = self.find_file('cv/face/david2.jpg', [os.environ.get('OPENCV_TEST_DATA_PATH')])
+            in1 = cv.cvtColor(cv.imread(img_path), cv.COLOR_RGB2GRAY)
+
+            # NB: goodFeaturesToTrack configuration
+            max_corners         = 50
+            quality_lvl         = 0.01
+            min_distance        = 10
+            block_sz            = 3
+            use_harris_detector = True
+            k                   = 0.04
+            mask                = None
+
+            # OpenCV
+            expected = cv.goodFeaturesToTrack(in1, max_corners, quality_lvl,
+                                              min_distance, mask=mask,
+                                              blockSize=block_sz, useHarrisDetector=use_harris_detector, k=k)
+
+            # G-API
+            g_in = cv.GMat()
+            g_out = cv.gapi.goodFeaturesToTrack(g_in, max_corners, quality_lvl,
+                                                min_distance, mask, block_sz, use_harris_detector, k)
+
+            comp = cv.GComputation(cv.GIn(g_in), cv.GOut(g_out))
+
+            for pkg_name, pkg in pkgs:
+                actual = comp.apply(cv.gin(in1), args=cv.gapi.compile_args(pkg))
+                # NB: OpenCV & G-API have different output shapes:
+                # OpenCV - (num_points, 1, 2)
+                # G-API  - (num_points, 2)
+                # Comparison
+                self.assertEqual(0.0, cv.norm(expected.flatten(),
+                                              np.array(actual, dtype=np.float32).flatten(),
+                                              cv.NORM_INF),
+                                 'Failed on ' + pkg_name + ' backend')
+
+
+        def test_rgb2gray(self):
+            # TODO: Extend to use any type and size here
+            img_path = self.find_file('cv/face/david2.jpg', [os.environ.get('OPENCV_TEST_DATA_PATH')])
+            in1 = cv.imread(img_path)
+
+            # OpenCV
+            expected = cv.cvtColor(in1, cv.COLOR_RGB2GRAY)
+
+            # G-API
+            g_in = cv.GMat()
+            g_out = cv.gapi.RGB2Gray(g_in)
+
+            comp = cv.GComputation(cv.GIn(g_in), cv.GOut(g_out))
+
+            for pkg_name, pkg in pkgs:
+                actual = comp.apply(cv.gin(in1), args=cv.gapi.compile_args(pkg))
+                # Comparison
+                self.assertEqual(0.0, cv.norm(expected, actual, cv.NORM_INF),
+                                 'Failed on ' + pkg_name + ' backend')
+
+
+        def test_bounding_rect(self):
+            sz = 1280
+            fscale = 256
+
+            def sample_value(fscale):
+                return np.random.uniform(0, 255 * fscale) / fscale
+
+            points = np.array([(sample_value(fscale), sample_value(fscale)) for _ in range(1280)], np.float32)
+
+            # OpenCV
+            expected = cv.boundingRect(points)
+
+            # G-API
+            g_in  = cv.GMat()
+            g_out = cv.gapi.boundingRect(g_in)
+
+            comp = cv.GComputation(cv.GIn(g_in), cv.GOut(g_out))
+
+            for pkg_name, pkg in pkgs:
+                actual = comp.apply(cv.gin(points), args=cv.gapi.compile_args(pkg))
+                # Comparison
+                self.assertEqual(0.0, cv.norm(expected, actual, cv.NORM_INF),
+                                 'Failed on ' + pkg_name + ' backend')
+
+
+except unittest.SkipTest as e:
+
+    message = str(e)
+
+    class TestSkip(unittest.TestCase):
+        def setUp(self):
+            self.skipTest('Skip tests: ' + message)
+
+        def test_skip():
+            pass
+
+    pass
+
+
+if __name__ == '__main__':
+    NewOpenCVTests.bootstrap()