0、环境
- Anaconda3-2020.02-Windows-x86_64（Python 3.7.6 ）
- opencv_python-4.4.0.40-cp37-cp37m-win_amd64.whl(可选)
- VS2012
1、找不到inttypes.h
在VS 2012中编译会报inttypes.h错误，可以直接在C:\Program Files (x86)\Microsoft Visual Studio 11.0\VC\include 目录下新建inttypes.h文件，文件内容如下：
#pragma once
#include
2、找不到Py_InitModule()
网上例子是在python2环境下，python3已经弃用该方法，具体使用可参考官方文档，根据网上例子python c 扩展 ctype 以及 效率对比稍作修改。
#include
static PyObject *
spam_add(PyObject * self,PyObject *args)
{
long a;
//将python中传入的变量转化成C中的变量
if(!PyArg_ParseTuple(args,"l",&a))
return NULL;
long long tmp=0;
for(long i = 1;i<=a;i++)
tmp +=i;
//将C中的变量转化成python中的变量
return Py_BuildValue("L",tmp);
}
//方法定义
static PyMethodDef SpamMethods[] = {
//每个方法都有四个属性
//分别为 1、python中方法名 2、c中名称
//3、应该就是传入的参数
//4、方法描述
{"add",spam_add,METH_VARARGS,"Return the cumulative value "},
//这个是必须加的，应该都一样吧
{NULL, NULL, 0, NULL} /* Sentinel */
};
static struct PyModuleDef SpamModule = {
PyModuleDef_HEAD_INIT,
"IRCam",
NULL,
-1,
SpamMethods
};
//初始化模块
//PyInit_IRCamDll名称 必须跟 IRCamDll库文件名称关联
//可以如下测试：
//import spam
//dir(spam)
PyMODINIT_FUNC
PyInit_IRCamDll(void)
{
return PyModule_Create(&SpamModule);
}
3、链接无法打开python37_d.lib错误
这个是debug库，环境没自带，那就把C++工程用release编译吧！
4、对象扩展
前面只是扩展了C函数，下面代码实现扩展类对象，结构体类型类似，通过PyCapsule_New、PyCapsule_GetPointer实现。
C++代码
#include
class CamCapture
{
public:
~CamCapture(){printf("~CamCapture\r\n");}
CamCapture(int first, double second)
: m_first( first), m_second(second){printf("CamCapture()\r\n");}
double Test1(void){ return m_first*m_second;}
private:
int m_first;
double m_second;
};
static void PyDelCamCaptureDetector(PyObject *obj)
{
printf("CameraCapture_UnInit\n");
CamCapture * tmp = (CamCapture *) PyCapsule_GetPointer(obj, "CamCapture");
delete tmp;
return;
}
PyObject *CamCapture_Init(PyObject *, PyObject* args)
{
int arg1;
double arg2;
printf("CameraCapture_Init\n");
int ok = PyArg_ParseTuple(args,"id",&arg1,&arg2);
if(!ok) return NULL;
//动态创建一个新对象
CamCapture *camCapture = new CamCapture(arg1, arg2);
//把指针camCapture包装成PyCObject对象并返回给解释器
return PyCapsule_New(camCapture, "CamCapture", PyDelCamCaptureDetector);
//PyCapsule_New(camCapture, "CamCapture", must_free ? PyDelCamCaptureDetector : NULL);
//return PyCObject_FromVoidPtr(camCapture, PyDelCamCaptureDetector);
}
PyObject * CamCapture_Test1(PyObject *, PyObject* args)
{
PyObject *pyobj = 0;
int ok = PyArg_ParseTuple( args, "O", &pyobj);
if(!ok) return NULL;
//把PyCObject转换为void指针
// void * temp = PyCObject_AsVoidPtr(pyobj);
void * temp = (CamCapture *) PyCapsule_GetPointer(pyobj, "CamCapture");
//把void指针转换为一个CamCapture对象指针
CamCapture *camCapture = static_cast(temp);
//调用函数
double result = camCapture->Test1();
//返回结果
return Py_BuildValue("d",result);
}
PyObject * CamCapture_Test2(PyObject *, PyObject* args)
{
return Py_BuildValue("(is)",5,"V5");
}
static PyMethodDef DllMethods[] = {
{"CamCapture", CamCapture_Init, METH_VARARGS, "Init"},
{"Test1", CamCapture_Test1, METH_VARARGS, "Test1"},
{"Test2", CamCapture_Test2, METH_VARARGS, "Test2"},
{NULL, NULL, 0, NULL}
};
static struct PyModuleDef DllModule = {
PyModuleDef_HEAD_INIT,
"IRCam",//name of module
NULL,//module documentation, may be NULL
-1,//size of per-interpreter state of the module, or -1 if the module keeps state in global variables.
DllMethods
};
//初始化模块
//PyInit_IRCamDll名称 必须跟 IRCamDll库文件名称关联
PyMODINIT_FUNC
PyInit_IRCamDll(void)
{
return PyModule_Create(&DllModule);
}
python测试代码
from IRCamDll import *
class IRCam(object):
def __init__(self,arg1,arg2):
self._base = CamCapture(arg1,arg2)
def Test1(self):
return Test1(self._base)
def Test2(self):
return Test2(self._base)
obj = IRCam(2, 100)
print(obj.Test1())
print(obj.Test2())
ri,rs = obj.Test2()
print(ri + 1)
print(rs + "V6")
obj1 = IRCam(4, 1000)
print(obj1.Test1())
print(obj1.Test2())
A、参考资料
Python C++扩展
python扩展之C++篇
windows下python调用C/C++以及使用C扩展python
Python的C/C++扩展
Python/c Api 扩展解析
『Python CoolBook』C扩展库其四结构体操作与Capsule