Updated cv2.cpp to support Python 3 API.

Added a header with defines to enable the module to compile with either
python 2 or 3 without changes.

modules/python/src2/cv2.cpp

@@ -23,6 +23,8 @@
 #  include "opencv2/nonfree.hpp"
 #endif
 
+#include "pycompat.hpp"
+
 using cv::flann::IndexParams;
 using cv::flann::SearchParams;
 
@@ -1176,7 +1178,11 @@ static int convert_to_char(PyObject *o, char *dst, const char *name = "no_name")
   }
 }
 
+#if PY_MAJOR_VERSION >= 3
+#define MKTYPE2(NAME) pyopencv_##NAME##_specials(); if (!to_ok(&pyopencv_##NAME##_Type)) return NULL;
+#else
 #define MKTYPE2(NAME) pyopencv_##NAME##_specials(); if (!to_ok(&pyopencv_##NAME##_Type)) return
+#endif
 
 #ifdef __GNUC__
 #  pragma GCC diagnostic ignored "-Wunused-parameter"
@@ -1205,15 +1211,35 @@ static int to_ok(PyTypeObject *to)
   return (PyType_Ready(to) == 0);
 }
 
+
+#if PY_MAJOR_VERSION >= 3
+extern "C" CV_EXPORTS PyObject* PyInit_cv2();
+static struct PyModuleDef cv2_moduledef =
+{
+    PyModuleDef_HEAD_INIT,
+    MODULESTR,
+    "Python wrapper for OpenCV.",
+    -1,     /* size of per-interpreter state of the module,
+               or -1 if the module keeps state in global variables. */
+    methods
+};
+
+PyObject* PyInit_cv2()
+#else
 extern "C" CV_EXPORTS void initcv2();
 
 void initcv2()
+#endif
 {
   import_array();
 
 #include "pyopencv_generated_type_reg.h"
 
+#if PY_MAJOR_VERSION >= 3
+  PyObject* m = PyModule_Create(&cv2_moduledef);
+#else
   PyObject* m = Py_InitModule(MODULESTR, methods);
+#endif
   PyObject* d = PyModule_GetDict(m);
 
   PyDict_SetItemString(d, "__version__", PyString_FromString(CV_VERSION));
@@ -1262,5 +1288,7 @@ void initcv2()
   PUBLISH(CV_64FC4);
 
 #include "pyopencv_generated_const_reg.h"
-
+#if PY_MAJOR_VERSION >= 3
+    return m;
+#endif
 }

modules/python/src2/pycompat.hpp

@@ -0,0 +1,64 @@
+/*M///////////////////////////////////////////////////////////////////////////////////////
+//
+//  IMPORTANT: READ BEFORE DOWNLOADING, COPYING, INSTALLING OR USING.
+//
+//  By downloading, copying, installing or using the software you agree to this license.
+//  If you do not agree to this license, do not download, install,
+//  copy or use the software.
+//
+//
+//                           License Agreement
+//                For Open Source Computer Vision Library
+//
+// Copyright (C) 2000-2008, Intel Corporation, all rights reserved.
+// Copyright (C) 2009-2011, Willow Garage Inc., all rights reserved.
+// Third party copyrights are property of their respective owners.
+//
+// Redistribution and use in source and binary forms, with or without modification,
+// are permitted provided that the following conditions are met:
+//
+//   * Redistribution's of source code must retain the above copyright notice,
+//     this list of conditions and the following disclaimer.
+//
+//   * Redistribution's in binary form must reproduce the above copyright notice,
+//     this list of conditions and the following disclaimer in the documentation
+//     and/or other materials provided with the distribution.
+//
+//   * The name of the copyright holders may not be used to endorse or promote products
+//     derived from this software without specific prior written permission.
+//
+// This software is provided by the copyright holders and contributors "as is" and
+// any express or implied warranties, including, but not limited to, the implied
+// warranties of merchantability and fitness for a particular purpose are disclaimed.
+// In no event shall the Intel Corporation or contributors be liable for any direct,
+// indirect, incidental, special, exemplary, or consequential damages
+// (including, but not limited to, procurement of substitute goods or services;
+// loss of use, data, or profits; or business interruption) however caused
+// and on any theory of liability, whether in contract, strict liability,
+// or tort (including negligence or otherwise) arising in any way out of
+// the use of this software, even if advised of the possibility of such damage.
+//
+//M*/
+
+// Defines for Python 2/3 compatibility.
+#ifndef __PYCOMPAT_HPP__
+#define __PYCOMPAT_HPP__
+
+#if PY_MAJOR_VERSION >= 3
+// Python3 treats all ints as longs, PyInt_X functions have been removed.
+#define PyInt_Check PyLong_Check
+#define PyInt_CheckExact PyLong_CheckExact
+#define PyInt_AsLong PyLong_AsLong
+#define PyInt_AS_LONG PyLong_AS_LONG
+#define PyInt_FromLong PyLong_FromLong
+#define PyNumber_Int PyNumber_Long
+
+// Python3 strings are unicode, these defines mimic the Python2 functionality.
+#define PyString_Check PyUnicode_Check
+#define PyString_FromString PyUnicode_FromString
+#define PyString_AsString PyUnicode_AsUTF8
+#define PyString_FromStringAndSize PyUnicode_FromStringAndSize
+#define PyString_Size PyUnicode_GET_SIZE
+#endif
+
+#endif // END HEADER GUARD