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Export C API in python module
- Allows converting Mat to NDArray and back
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‎modules/python/include/opencv2/python/pyapi.hpp

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/**
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Utility API for converting Python types to/from OpenCV types
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This is useful when you have a python module that links to a C++ library that
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uses OpenCV, and you need to convert things to/from python.
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For now, this only supports converting Mat objects, but in the future
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other types of conversions may be supported.
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This code is copied wholesafe from numpy's generate_numpy_api.py
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Copyright (c) 2005-2016, NumPy Developers.
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are
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met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above
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copyright notice, this list of conditions and the following
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disclaimer in the documentation and/or other materials provided
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with the distribution.
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* Neither the name of the NumPy Developers nor the names of any
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef __PYCV2_API
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#define __PYCV2_API
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#include <Python.h>
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#include <opencv2/core/core.hpp>
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#if defined(PY_OPENCV_UNIQUE_SYMBOL)
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#define PyOpenCV_API PY_OPENCV_UNIQUE_SYMBOL
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#endif
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#if defined(NO_IMPORT) || defined(NO_IMPORT_OPENCV)
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extern void **PyOpenCV_API;
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#else
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#if defined(PY_OPENCV_UNIQUE_SYMBOL)
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void **PyOpenCV_API;
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#else
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static void **PyOpenCV_API=NULL;
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#endif
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#endif
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#if !defined(NO_IMPORT_OPENCV) && !defined(NO_IMPORT)
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static int
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_import_opencv(void)
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{
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//int st;
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PyObject *cv2 = PyImport_ImportModule("cv2");
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PyObject *c_api = NULL;
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if (cv2 == NULL) {
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PyErr_SetString(PyExc_ImportError, "cv2 failed to import");
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return -1;
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}
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c_api = PyObject_GetAttrString(cv2, "_OPENCV_API");
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Py_DECREF(cv2);
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if (c_api == NULL) {
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PyErr_SetString(PyExc_AttributeError, "_OPENCV_API not found");
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return -1;
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}
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#if PY_VERSION_HEX >= 0x03000000
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if (!PyCapsule_CheckExact(c_api)) {
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PyErr_SetString(PyExc_RuntimeError, "_OPENCV_API is not PyCapsule object");
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Py_DECREF(c_api);
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return -1;
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}
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PyOpenCV_API = (void **)PyCapsule_GetPointer(c_api, NULL);
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#else
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if (!PyCObject_Check(c_api)) {
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PyErr_SetString(PyExc_RuntimeError, "_OPENCV_API is not PyCObject object");
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Py_DECREF(c_api);
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return -1;
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}
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PyOpenCV_API = (void **)PyCObject_AsVoidPtr(c_api);
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#endif
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Py_DECREF(c_api);
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if (PyOpenCV_API == NULL) {
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PyErr_SetString(PyExc_RuntimeError, "_OPENCV_API is NULL pointer");
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return -1;
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}
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/* TODO? Perform runtime check of C API version */
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/*
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if (NPY_VERSION != PyArray_GetNDArrayCVersion()) {
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PyErr_Format(PyExc_RuntimeError, "module compiled against "\
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"ABI version 0x%%x but this version of numpy is 0x%%x", \
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(int) NPY_VERSION, (int) PyArray_GetNDArrayCVersion());
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return -1;
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}
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if (NPY_FEATURE_VERSION > PyArray_GetNDArrayCFeatureVersion()) {
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PyErr_Format(PyExc_RuntimeError, "module compiled against "\
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"API version 0x%%x but this version of numpy is 0x%%x", \
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(int) NPY_FEATURE_VERSION, (int) PyArray_GetNDArrayCFeatureVersion());
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return -1;
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}
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*/
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/*
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* TODO? Perform runtime check of endianness and check it matches the one set by
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* the headers (npy_endian.h) as a safeguard
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*/
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/*
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st = PyArray_GetEndianness();
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if (st == NPY_CPU_UNKNOWN_ENDIAN) {
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PyErr_Format(PyExc_RuntimeError, "FATAL: module compiled as unknown endian");
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return -1;
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}
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#if NPY_BYTE_ORDER == NPY_BIG_ENDIAN
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if (st != NPY_CPU_BIG) {
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PyErr_Format(PyExc_RuntimeError, "FATAL: module compiled as "\
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"big endian, but detected different endianness at runtime");
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return -1;
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}
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#elif NPY_BYTE_ORDER == NPY_LITTLE_ENDIAN
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if (st != NPY_CPU_LITTLE) {
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PyErr_Format(PyExc_RuntimeError, "FATAL: module compiled as "\
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"little endian, but detected different endianness at runtime");
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return -1;
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}
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#endif
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*/
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return 0;
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}
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#if PY_VERSION_HEX >= 0x03000000
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#define OPENCV_IMPORT_RETVAL NULL
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#else
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#define OPENCV_IMPORT_RETVAL
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#endif
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#define import_opencv() {if (_import_opencv() < 0) {PyErr_Print(); PyErr_SetString(PyExc_ImportError, "cv2 failed to import"); return OPENCV_IMPORT_RETVAL; } }
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#define import_opencv1(ret) {if (_import_opencv() < 0) {PyErr_Print(); PyErr_SetString(PyExc_ImportError, "cv2 failed to import"); return ret; } }
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#define import_opencv2(msg, ret) {if (_import_opencv() < 0) {PyErr_Print(); PyErr_SetString(PyExc_ImportError, msg); return ret; } }
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/**
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Exported API, must call import_opencv first!
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*/
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#define PyOpenCV_MatToNdarray \
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(*(PyObject * (*)(const cv::Mat&)) \
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PyOpenCV_API[0])
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#define PyOpenCV_NdarrayToMat \
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(*(bool (*)(PyObject *, cv::Mat&, const char *)) \
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PyOpenCV_API[1])
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#define PyOpenCV_UMatToNdarray \
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(*(PyObject * (*)(const cv::UMat&)) \
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PyOpenCV_API[2])
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#define PyOpenCV_NdarrayToUMat \
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(*(bool (*)(PyObject *, cv::UMat&, const char *)) \
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PyOpenCV_API[3])
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#endif
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#endif

‎modules/python/src2/cv2.cpp

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@@ -1374,6 +1374,17 @@ static PyMethodDef special_methods[] = {
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/************************************************************************/
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/* Module init */
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void * PyOpenCV_API[] = {
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// 0: PyOpenCV_MatToNdarray
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reinterpret_cast<void*>(static_cast<PyObject * (*)(const Mat&)>(&pyopencv_from)),
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// 1: PyOpenCV_NdarrayToMat
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reinterpret_cast<void*>(static_cast<bool (*)(PyObject *, Mat&, const char *)>(&pyopencv_to)),
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// 2: PyOpenCV_UMatToNdarray
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reinterpret_cast<void*>(static_cast<PyObject * (*)(const UMat&)>(&pyopencv_from)),
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// 3: PyOpenCV_NdarrayToUMat
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reinterpret_cast<void*>(static_cast<bool (*)(PyObject *, UMat&, const char *)>(&pyopencv_to)),
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};
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struct ConstDef
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{
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const char * name;
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#endif
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PyModule_AddObject(m, "UMat", (PyObject *)&cv2_UMatWrapperType);
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PyObject * c_api = PyCapsule_New(PyArray_API, NULL, NULL);
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PyDict_SetItemString(d, "_OPENCV_API", c_api);
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Py_DECREF(c_api);
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#define PUBLISH(I) PyDict_SetItemString(d, #I, PyInt_FromLong(I))
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//#define PUBLISHU(I) PyDict_SetItemString(d, #I, PyLong_FromUnsignedLong(I))
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#define PUBLISH2(I, value) PyDict_SetItemString(d, #I, PyLong_FromLong(value))

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