如何用Boost::Python包装C++OpenCV代码

How do you wrap C++ OpenCV code with Boost::Python?

本文关键字:C++OpenCV 代码 包装 Python Boost 何用      更新时间:2023-10-16

我想用boost::python包装我的C++OpenCV代码,为了学习如何做到这一点,我尝试了一个玩具示例,其中

  • 我使用Boost.Numbery项目为我提供boost::numpy::ndarray

  • 要包装的C++函数square()采用boost::numpy::ndarray,并通过对其中的每个元素进行平方来对其进行适当的修改。

  • 导出的Python模块名称称为test

  • square() C++函数作为导出模块中的square名称导出。

  • 使用bjam,因为IMO它太复杂了,无论如何都不适合我。我用的是好的旧make

现在,这是代码:

// test.cpp
#include <boost/python.hpp>
#include <boost/numpy.hpp>
#include <boost/scoped_array.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <iostream>
namespace py = boost::python;
namespace np = boost::numpy;
void square(np::ndarray& array)
{
    if (array.get_dtype() != np::dtype::get_builtin<int>())
    {
        PyErr_SetString(PyExc_TypeError, "Incorrect array data type.");
        py::throw_error_already_set();
    }
    size_t rows = array.shape(0), cols = array.shape(1);
    size_t stride_row = array.strides(0) / sizeof(int), 
           stride_col = array.strides(1) / sizeof(int);
    cv::Mat mat(rows, cols, CV_32S);
    int *row_iter = reinterpret_cast<int*>(array.get_data());
    for (int i = 0; i < rows; i++, row_iter += stride_row)
    {
        int *col_iter = row_iter;
        int *mat_row = (int*)mat.ptr(i);
        for (int j = 0; j < cols; j++, col_iter += stride_col)
        {
            *(mat_row + j) = (*col_iter) * (*col_iter); 
        }
    }
    for (int i = 0; i < rows; i++, row_iter += stride_row)
    {
        int *col_iter = row_iter;
        int *mat_row = (int*)mat.ptr(i);
        for (int j = 0; j < cols; j++, col_iter += stride_col)
        {
            *col_iter = *(mat_row + j);
        }
    }
}

BOOST_PYTHON_MODULE(test)
{
   using namespace boost::python;
   def("square", square);
}

这是Makefile:

PYTHON_VERSION = 2.7
PYTHON_INCLUDE = /usr/include/python$(PYTHON_VERSION)
BOOST_INC = /usr/local/include
BOOST_LIB = /usr/local/lib
OPENCV_LIB = $$(pkg-config --libs opencv)
OPENCV_INC = $$(pkg-config --cflags opencv)
TARGET = test
$(TARGET).so: $(TARGET).o
        g++ -shared -Wl,--export-dynamic 
        $(TARGET).o -L$(BOOST_LIB) -lboost_python 
        $(OPENCV_LIB) 
        -L/usr/lib/python$(PYTHON_VERSION)/config -lpython$(PYTHON_VERSION) 
        -o $(TARGET).so
$(TARGET).o: $(TARGET).cpp
        g++ -I$(PYTHON_INCLUDE) $(OPENCV_INC) -I$(BOOST_INC) -fPIC -c $(TARGET).cpp

使用此方案,我可以键入make,然后创建test.so。但当我尝试导入它时,

In [1]: import test
---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
<ipython-input-1-73ae3ffe1045> in <module>()
----> 1 import test
ImportError: ./test.so: undefined symbol:        _ZN5boost6python9converter21object_manager_traitsINS_5numpy7ndarrayEE10get_pytypeEv
In [2]: 

这是一个链接器错误,我似乎无法修复。有人能帮我了解一下发生了什么事吗你有没有(链接到)已经集成了OpenCV、numpy和Boost.Python的代码,而没有Py++之类的东西

好的,我解决了这个问题。这是一个简单的问题,但昏昏欲睡的大脑和几份bjam让我忽略了它。在Makefile中,我忘了放-lboost_numpy,它将Boost.Numbery库链接到我的库。因此,修改后的Makefile看起来是这样的:

PYTHON_VERSION = 2.7
PYTHON_INCLUDE = /usr/include/python$(PYTHON_VERSION)
BOOST_INC = /usr/local/include
BOOST_LIB = /usr/local/lib
OPENCV_LIB = $$(pkg-config --libs opencv)
OPENCV_INC = $$(pkg-config --cflags opencv)
TARGET = test
$(TARGET).so: $(TARGET).o
        g++ -shared -Wl,--export-dynamic 
        $(TARGET).o -L$(BOOST_LIB) -lboost_python -lboost_numpy 
        $(OPENCV_LIB) 
        -L/usr/lib/python$(PYTHON_VERSION)/config -lpython$(PYTHON_VERSION) 
        -o $(TARGET).so
$(TARGET).o: $(TARGET).cpp
        g++ -I$(PYTHON_INCLUDE) $(OPENCV_INC) -I$(BOOST_INC) -fPIC -c $(TARGET).cpp