標簽（空格分隔）： C/C++ python python調(diào)用C 人工智能 AI
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python訪問C/C++
- python的底層大部分都是C/C++實現(xiàn),python和C和C++具有天然的互相調(diào)用優(yōu)勢;
- 很多核心的算法庫都是C/C++寫的,在python開發(fā)過程中,經(jīng)常訪問別人的動態(tài)庫;
- 知名人工智能(深度學習)框架訓練系統(tǒng)都是python寫的,而運行時一般都是以動態(tài)庫的形式提供;
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python訪問C/C++的方式
- ctypes乡洼；
- pybind11；
- cffi
- swig
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ctypes的優(yōu)勢
- 不要修改動態(tài)庫的源碼;
- 只需要動態(tài)庫和頭文件;
- 使用比較簡單,而且目前大部分庫都是兼容C/C++;
本文以一個典型的深度學習(人工智能AI)的圖像檢測的python自動化測試,介紹ctypes的使用;
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ctypes的使用
結(jié)構(gòu)體頭文件:
//
// Created by yinlib on 18-12-4.
//
#ifndef CVIMAGETEST_CV_COMMON_H
#define CVIMAGETEST_CV_COMMON_H
#ifdef __MSC_VER
# define CV_IMAGE_API_ __declspec(dllexport)
#else
# define CV_IMAGE_API_ __attribute__((visibility("default")))
#endif
#ifdef __cplusplus
# define CV_IMAGE_API extern "C" CV_IMAGE_API_
#else
# define CV_IMAGE_API CV_IMAGE_API_
#endif
#define RC_OK 0
#define RC_E_HANDLE -1
#define RC_E_INVALIDARG -2
#define RC_E_OUTOFMEMORY -3
#define RC_E_INVALID_FORMAT -4
#define RC_E_FAIL -5
typedef void *mt_handle_t;
typedef int mt_result_t;
typedef struct rect_t{
int left;
int top;
int right;
int bottom;
} rect_t;
typedef struct point3f_t{
float x;
float y;
float z;
}point_t;
typedef struct extra_info_t{
float mvp_mat[3][3];
point_t *points_ori;
int point_count;
}extra_info_t;
typedef struct detection_result_t{
rect_t rect;
float score;
int label;
int orientation;
extra_info_t extra_info;
} detection_result_t;
#endif //CVIMAGETEST_CV_COMMON_H
接口頭文件:
#pragma once
#include "mt_image_common.h"
CV_IMAGE_API
mt_result_t
mt_image_detect_init_config(const char* congif);
CV_IMAGE_API
mt_result_t
mt_image_detect_create(const char* model_path, mt_handle_t* handle);
CV_IMAGE_API
void
mt_image_detect_destroy(mt_handle_t handle);
CV_IMAGE_API
void
mt_image_release_detect_result(detection_result_t* detection_result, int count);
CV_IMAGE_API
mt_result_t
mt_image_detect_compact(mt_handle_t handle, const unsigned char* img, int format, int image_width,
int image_height, int image_stride, detection_result_t** detect_info, int* count);
CV_IMAGE_API
mt_result_t
mt_image_detect_reset(mt_handle_t handle);
結(jié)構(gòu)體的映射:
from ctypes import *
import os
import shutil
class rect_t(Structure):
pass
rect_t._fields_ = [
('left', c_int),
('top', c_int),
('right', c_int),
('bottom', c_int),
]
class point3f_t(Structure):
pass
point3f_t._fields_ = [
('x', c_float),
('y', c_float),
('z', c_float),
]
class extra_info(Structure):
pass
extra_info._fields_ = [
('mvp_mat', c_float*3*3),
('point_t', POINTER(point3f_t)),
('point_count', c_int),
]
class detection_result(Structure):
pass
detection_result._fields_ = [
('rect', rect_t),
('score', c_float),
('label', c_int),
('orientation', c_int),
('extra_info', extra_info),
]
def movefile(srcpath, dstpath):
if not os.path.isfile(srcpath):
print(srcpath + ' is not exist!')
else:
fpath, fname = os.path.split(dstpath)
if not os.path.exists(fpath):
os.makedirs(fpath)
shutil.copy(srcpath, dstpath)
print('copy ' + srcpath + '->' + dstpath)
接口映射:
import ctypes
import os
class MtLibrary:
def __init__(self, path):
self.path = path
self.lib = None
self.hasInit = False
def load_library(self):
dl = ctypes.cdll.LoadLibrary
print('load_library lib is Exist : ' + str(os.path.exists(self.path)))
print(os.getcwd())
lib = dl(self.path)
self.lib = lib
self.hasInit = True
def init_license(self, licence):
if not self.hasInit:
print('lib has not init!!')
return False
licence_context = bytes(licence, "utf8")
return self.lib.mt_image_detect_init_config(licence_context)
def create_handle(self, path, handle):
if not self.hasInit:
print('lib has not init!!')
return None
return self.lib.mt_image_detect_create(path, handle)
def reset_handle(self, handle):
return self.lib.mt_image_detect_reset(handle)
def detect_image(self, handle, image, format, width, height, stride, detect_info, count):
if not self.hasInit:
print('lib has not init!!')
return None
return self.lib.mt_image_detect_compact(handle, image, format, width, height, stride, detect_info, count)
def release_result(self, detect_result, count):
if not self.hasInit:
print("lib has not init!!")
return None
return self.lib.mt_image_release_detect_result(detect_result, count)
def destroy_handle(self, handle):
if not self.hasInit:
print("lib has not init!!")
return None
return self.lib.mt_image_detect_destroy(handle)
重點問題:
- 結(jié)構(gòu)體和復雜結(jié)構(gòu)提的映射
C中的結(jié)構(gòu)體
typedef struct extra_info_t{
float mvp_mat[3][3];
point_t *points_ori;
int point_count;
}extra_info_t;
typedef struct detection_result_t{
rect_t rect;
float score;
int label;
int orientation;
extra_info_t extra_info;
} detection_result_t;
Python中的類
class extra_info(Structure):
pass
extra_info._fields_ = [
('mvp_mat', c_float*3*3),
('point_t', POINTER(point3f_t)),
('point_count', c_int),
]
class detection_result(Structure):
pass
detection_result._fields_ = [
('rect', rect_t),
('score', c_float),
('label', c_int),
('orientation', c_int),
('extra_info', extra_info),
]
多維數(shù)組
float mvp_mat[3][3] --> c_float33
數(shù)組指針
point_t *points_ori --> POINTER(point3f_t)
- 調(diào)用時指針(二級指針)的映射
CV_IMAGE_API
mt_result_t
mt_image_detect_compact(mt_handle_t handle, const unsigned char* img, int format, int image_width,
int image_height, int image_stride, detection_result_t** detect_info, int* count);
python調(diào)用:
TARGETPOINTER_t = POINTER(detection_result)
result_handle = TARGETPOINTER_t()
print('result_handle: ' + str(result_handle))
count = c_int(0)
status = mt_image_detect.detect_image(handle, byref(image_data), 0, width, height, width * 3, byref(result_handle), pointer(count))
print('detect_image status: ' + str(status) + " count : " + str(count.value))
detect_content = result_handle.contents
針對于二級指針,必須POINTER(detection_result)生成T*,然后創(chuàng)建result_handle = TARGETPOINTER_t(),然后通過byref(result_handle)得到二級指針
- byref(n)返回的相當于C的指針右值&n，本身沒有被分配空間;
- pointer返回的相當于指針左值T* p=&n广匙，可以改變裤园，可以取地址; POINTER得到是類;
調(diào)用結(jié)果
/home/sensetime/miniconda3/envs/pythonPIL/bin/python /home/sensetime/jayzwang/workspace/clion_workspace/PyImageTest/image_test.py
copy ../CvImageTest/build/libmtimage.so->./extents/libs/libmtimage.so
copy ../CvImageTest/mt_image_common.h->./extents/include/mt_image_common.h
copy ../CvImageTest/mt_image_detect.h->./extents/include/mt_image_detect.h
test license
load_library lib is Exist : True
/home/sensetime/jayzwang/workspace/clion_workspace/PyImageTest
mt_image_detect_init_config.14: in
init_license : 0
mt_image_detect_create.24: in
create_handle : 0 handle : c_long(94128605088976)
pil image : 768 height : 576
width : 768 height : 576 format : None
image pointer : <cparam 'P' (0x559c061f1960)> image_date [-1] : 255
result_handle: <__main__.LP_detection_result object at 0x7fd92de1d1e0>
mt_image_detect_compact.62: in
mt_image_detect_compact.75: mt_image_detect_compact : 0x559c060ce080
detect_image status: 0 count : 1
detect result left : 20
detect result label: 1
detect result points: 1
mt_image_detect_reset.82: in
reset_handle status: 0
mt_image_release_detect_result.46: in
mt_image_detect_destroy.34: in
destroy_handle status: 0 handle : c_long(94128605088976)
其他:
- 文件移動
def movefile(srcpath, dstpath):
if not os.path.isfile(srcpath):
print(srcpath + ' is not exist!')
else:
fpath, fname = os.path.split(dstpath)
if not os.path.exists(fpath):
os.makedirs(fpath)
shutil.copy(srcpath, dstpath)
print('copy ' + srcpath + '->' + dstpath)
- 圖片讀取和轉(zhuǎn)碼,使用pil讀取,并轉(zhuǎn)換成BGR(AI/深度學習的大部分輸入都是BGR)
hand_image = Image.open('./extents/test_image/timg.jpeg')
hand_image = hand_image.convert('RGB')
width, height = hand_image.size
image_format = hand_image.format
image_data = (c_ubyte * (width * height * 3))()
print('pil image : ' + str(width) + " height : " + str(height))
# hand_image.show()
for x in range(height):
for y in range(width):
r, g, b = hand_image.getpixel((y, x))
#bgr = b, g, r
image_data[(x * width + y)*3] = b
image_data[(x * width + y)*3 + 1] = g
image_data[(x * width + y)*3 + 2] = r
- 寫文件
out_file = open('image_in', 'wb')
out_file.write(image_data)
out_file.close()
結(jié)語:
ctypes是非常輕量級的python調(diào)用C/C++的框架,非常適用于第三庫的測試,運行.能夠快速實現(xiàn)自動化測試,壓力測試等,十分實用;
