From 6fbf0758bc9b7108f22642899ffbf9c8c230bf7e Mon Sep 17 00:00:00 2001
From: Pavel Rojtberg <pavel.rojtberg@igd.fraunhofer.de>
Date: Thu, 27 Jul 2017 14:34:32 +0200
Subject: [PATCH 1/2] Python: wrap Algorithm::read and Algorithm::write

---
 modules/core/include/opencv2/core.hpp             |  9 +++++++--
 modules/core/src/algorithm.cpp                    | 13 +++++++++++++
 modules/features2d/include/opencv2/features2d.hpp | 13 +++++++++++--
 3 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/modules/core/include/opencv2/core.hpp b/modules/core/include/opencv2/core.hpp
index 8054d31b28..a1d196d677 100644
--- a/modules/core/include/opencv2/core.hpp
+++ b/modules/core/include/opencv2/core.hpp
@@ -3093,13 +3093,18 @@ public:
     */
     virtual void write(FileStorage& fs) const { (void)fs; }
 
+    /** @brief simplified API for language bindings
+     * @overload
+     */
+    CV_WRAP void write(const Ptr<FileStorage>& fs, const String& name = String()) const;
+
     /** @brief Reads algorithm parameters from a file storage
     */
-    virtual void read(const FileNode& fn) { (void)fn; }
+    CV_WRAP virtual void read(const FileNode& fn) { (void)fn; }
 
     /** @brief Returns true if the Algorithm is empty (e.g. in the very beginning or after unsuccessful read
      */
-    virtual bool empty() const { return false; }
+    CV_WRAP virtual bool empty() const { return false; }
 
     /** @brief Reads algorithm from the file node
 
diff --git a/modules/core/src/algorithm.cpp b/modules/core/src/algorithm.cpp
index 24f4dfb8b8..556f5a7328 100644
--- a/modules/core/src/algorithm.cpp
+++ b/modules/core/src/algorithm.cpp
@@ -55,6 +55,19 @@ Algorithm::~Algorithm()
     CV_TRACE_FUNCTION();
 }
 
+void Algorithm::write(const Ptr<FileStorage>& fs, const String& name) const
+{
+    CV_TRACE_FUNCTION();
+    if(name.empty())
+    {
+        write(*fs);
+        return;
+    }
+    *fs << name << "{";
+    write(*fs);
+    *fs << "}";
+}
+
 void Algorithm::save(const String& filename) const
 {
     CV_TRACE_FUNCTION();
diff --git a/modules/features2d/include/opencv2/features2d.hpp b/modules/features2d/include/opencv2/features2d.hpp
index 0ab11b63a1..119782bf1e 100644
--- a/modules/features2d/include/opencv2/features2d.hpp
+++ b/modules/features2d/include/opencv2/features2d.hpp
@@ -210,11 +210,15 @@ public:
 
     virtual void write( FileStorage&) const;
 
-    virtual void read( const FileNode&);
+    // see corresponding cv::Algorithm method
+    CV_WRAP virtual void read( const FileNode&);
 
     //! Return true if detector object is empty
     CV_WRAP virtual bool empty() const;
     CV_WRAP virtual String getDefaultName() const;
+
+    // see corresponding cv::Algorithm method
+    CV_WRAP inline void write(const Ptr<FileStorage>& fs, const String& name = String()) const { Algorithm::write(fs, name); }
 };
 
 /** Feature detectors in OpenCV have wrappers with a common interface that enables you to easily switch
@@ -985,7 +989,8 @@ public:
         read(fs.root());
     }
     // Reads matcher object from a file node
-    virtual void read( const FileNode& );
+    // see corresponding cv::Algorithm method
+    CV_WRAP virtual void read( const FileNode& );
     // Writes matcher object to a file storage
     virtual void write( FileStorage& ) const;
 
@@ -1012,6 +1017,10 @@ public:
 
     CV_WRAP static Ptr<DescriptorMatcher> create( int matcherType );
 
+
+    // see corresponding cv::Algorithm method
+    CV_WRAP inline void write(const Ptr<FileStorage>& fs, const String& name = String()) const { Algorithm::write(fs, name); }
+
 protected:
     /**
      * Class to work with descriptors from several images as with one merged matrix.

From 3c795a0dabb1c6bea6ad44c40937bdebaf523bb0 Mon Sep 17 00:00:00 2001
From: Pavel Rojtberg <pavel.rojtberg@igd.fraunhofer.de>
Date: Fri, 4 Aug 2017 17:12:20 +0200
Subject: [PATCH 2/2] add test_algorithm_rw using AKAZE

---
 modules/python/test/test_algorithm_rw.py | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)
 create mode 100644 modules/python/test/test_algorithm_rw.py

diff --git a/modules/python/test/test_algorithm_rw.py b/modules/python/test/test_algorithm_rw.py
new file mode 100644
index 0000000000..788fa220bc
--- /dev/null
+++ b/modules/python/test/test_algorithm_rw.py
@@ -0,0 +1,23 @@
+#!/usr/bin/env python
+
+'''
+Algorithm serializaion test
+'''
+import cv2
+
+from tests_common import NewOpenCVTests
+
+class algorithm_rw_test(NewOpenCVTests):
+    def test_algorithm_rw(self):
+        # some arbitrary non-default parameters
+        gold = cv2.AKAZE_create(descriptor_size=1, descriptor_channels=2, nOctaves=3, threshold=4.0)
+        gold.write(cv2.FileStorage("params.yml", 1), "AKAZE")
+
+        fs = cv2.FileStorage("params.yml", 0)
+        algorithm = cv2.AKAZE_create()
+        algorithm.read(fs.getNode("AKAZE"))
+
+        self.assertEqual(algorithm.getDescriptorSize(), 1)
+        self.assertEqual(algorithm.getDescriptorChannels(), 2)
+        self.assertEqual(algorithm.getNOctaves(), 3)
+        self.assertEqual(algorithm.getThreshold(), 4.0)