xfeatures2d(python): compatibility cv.xfeatures2d.SIFT_create()

modules/xfeatures2d/misc/python/pyopencv_sift.hpp

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+// Compatibility
+#include "shadow_sift.hpp"

modules/xfeatures2d/misc/python/shadow_sift.hpp

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+// Compatibility
+// SIFT is moved to the main repository
+
+namespace cv {
+namespace xfeatures2d {
+
+/** Use cv.SIFT_create() instead */
+CV_WRAP static inline
+Ptr<cv::SIFT> SIFT_create(int nfeatures = 0, int nOctaveLayers = 3,
+        double contrastThreshold = 0.04, double edgeThreshold = 10,
+        double sigma = 1.6)
+{
+    CV_LOG_ONCE_WARNING(NULL, "DEPRECATED: cv.xfeatures2d.SIFT_create() is deprecated due SIFT tranfer to the main repository. "
+                              "https://github.com/opencv/opencv/issues/16736"
+    );
+
+    return SIFT::create(nfeatures, nOctaveLayers, contrastThreshold, edgeThreshold, sigma);
+}
+
+}}  // namespace

modules/xfeatures2d/misc/python/test/test_sift_compatibility.py

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+#!/usr/bin/env python
+
+# Python 2/3 compatibility
+from __future__ import print_function
+
+import os
+import numpy as np
+import cv2 as cv
+
+from tests_common import NewOpenCVTests
+
+class sift_compatibility_test(NewOpenCVTests):
+
+    def test_create(self):
+
+        sift = cv.xfeatures2d.SIFT_create()
+        self.assertFalse(sift is None)
+
+        img1 = np.zeros((100, 100, 3), dtype=np.uint8)
+        kp1_, des1_ = sift.detectAndCompute(img1, None)
+
+
+if __name__ == '__main__':
+    NewOpenCVTests.bootstrap()