构建 Python 相机 SDK 并使用它进行多条码扫描
现在,轻量级 c 相机 sdk 已针对 windows、linux 和 macos 完成,我们可以将其集成到其他高级编程语言中。在本文中,我们将探讨如何基于 c 相机库构建 python 相机 sdk,并使用它与 dynamsoft barcode reader sdk 进行多条码扫描。
python 多条码扫描仪演示视频
github.com/user-attachments/assets/bfb7009b-2cff-42c8-a37c-c58a732f01f5" controls="controls">搭建 cpython 扩展项目的脚手架
cpython 扩展是一个共享库(例如,windows 上的 dll、linux 上的 .so 或 macos 上的 .dylib)可以在运行时加载到python解释器中并用于扩展其功能。 lite相机cpython扩展项目的结构如下:
python-lite-camera││── include│ ├── camera.h│ ├── camerapreview.h│ ├── stb_image_write.h│── lib│ ├── linux│ │ ├── liblitecam.so│ ├── macos│ │ ├── liblitecam.dylib│ ├── windows│ │ ├── litecam.dll│ │ ├── litecam.lib├── src│ ├── litecam.cpp│ ├── pycamera.h│ ├── pywindow.h│── litecam│ ├── __init__.py│── setup.py│── manifest.in│── readme.md
说明:
为 python 扩展编写构建脚本 setup.py
在setup.py中添加以下内容:
from setuptools.command import build_extfrom setuptools import setup, extensionimport sysimport osimport iofrom setuptools.command.install import installimport shutilfrom pathlib import pathlib_dir = ''sources = [ "src/litecam.cpp",]include_dirs = [os.path.join(os.path.dirname(__file__), "include")]libraries = ['litecam']extra_compile_args = []if sys.platform == "linux" or sys.platform == "linux2": lib_dir = 'lib/linux' extra_compile_args = ['-std=c++11'] extra_link_args = ["-wl,-rpath=$origin"]elif sys.platform == "darwin": lib_dir = 'lib/macos' extra_compile_args = ['-std=c++11'] extra_link_args = ["-wl,-rpath,@loader_path"]elif sys.platform == "win32": lib_dir = 'lib/windows' extra_link_args = []else: raise runtimeerror("unsupported platform")long_description = io.open("readme.md", encoding="utf-8").read()module_litecam = extension( "litecam", sources=sources, include_dirs=include_dirs, library_dirs=[lib_dir], libraries=libraries, extra_compile_args=extra_compile_args, extra_link_args=extra_link_args,)def copyfiles(src, dst): if os.path.isdir(src): filelist = os.listdir(src) for file in filelist: libpath = os.path.join(src, file) shutil.copy2(libpath, dst) else: shutil.copy2(src, dst)class custombuildext(build_ext.build_ext): def run(self): build_ext.build_ext.run(self) dst = os.path.join(self.build_lib, "litecam") copyfiles(lib_dir, dst) filelist = os.listdir(self.build_lib) for file in filelist: filepath = os.path.join(self.build_lib, file) if not os.path.isdir(file): copyfiles(filepath, dst) os.remove(filepath)class custombuildextdev(build_ext.build_ext): def run(self): build_ext.build_ext.run(self) dev_folder = os.path.join(path(__file__).parent, 'litecam') copyfiles(lib_dir, dev_folder) filelist = os.listdir(self.build_lib) for file in filelist: filepath = os.path.join(self.build_lib, file) if not os.path.isdir(file): copyfiles(filepath, dev_folder)class custominstall(install): def run(self): install.run(self)setup(name='lite-camera', version='2.0.1', description='litecam is a lightweight, cross-platform library for capturing rgb frames from cameras and displaying them. designed with simplicity and ease of integration in mind, litecam supports windows, linux and macos platforms.', long_description=long_description, long_description_content_type="text/markdown", author='yushulx', url='https://github.com/yushulx/python-lite-camera', license='mit', packages=['litecam'], ext_modules=[module_litecam], classifiers=[ "development status :: 5 - production/stable", "environment :: console", "intended audience :: developers", "intended audience :: education", "intended audience :: information technology", "intended audience :: science/research", "license :: osi approved :: mit license", "operating system :: microsoft :: windows", "operating system :: macos", "operating system :: posix :: linux", "programming language :: python", "programming language :: python :: 3", "programming language :: python :: 3 :: only", "programming language :: python :: 3.6", "programming language :: python :: 3.7", "programming language :: python :: 3.8", "programming language :: python :: 3.9", "programming language :: python :: 3.10", "programming language :: python :: 3.11", "programming language :: python :: 3.12", "programming language :: c++", "programming language :: python :: implementation :: cpython", "topic :: scientific/engineering", "topic :: software development", ], cmdclass={ 'install': custominstall, 'build_ext': custombuildext, 'develop': custombuildextdev}, )
说明:
用 c 实现 python camera sdk api
pycamera.h 文件定义了用于从相机捕获帧的 pycamera python 类,而 pywindow.h 文件定义了用于在窗口中显示帧的 pywindow python 类。 litecam.cpp 文件作为 python 扩展的入口点,其中定义了一些全局方法,并注册了 pycamera 和 pywindow 类。
pycamera.h
包括
#include <python.h>#include <structmember.h>#include "camera.h"
pycamera 结构体定义
typedef struct{ pyobject_head camera *handler;} pycamera;
pycamera 结构体表示包装 c camera 对象的 python 对象。该处理程序是一个指向 camera 类实例的指针。
立即学习“Python免费学习笔记(深入)”;
方法
实例方法
static pymethoddef instance_methods[] = { {"open", open, meth_varargs, null}, {"listmediatypes", listmediatypes, meth_varargs, null}, {"release", release, meth_varargs, null}, {"setresolution", setresolution, meth_varargs, null}, {"captureframe", captureframe, meth_varargs, null}, {"getwidth", getwidth, meth_varargs, null}, {"getheight", getheight, meth_varargs, null}, {null, null, 0, null}};
定义 pycamera python 对象上可用的方法。这些方法与上面定义的相应 c 函数相关联。
pycamera类型
static pytypeobject pycameratype = { pyvarobject_head_init(null, 0) "litecam.pycamera", /* tp_name */ sizeof(pycamera), /* tp_basicsize */ 0, /* tp_itemsize */ (destructor)pycamera_dealloc, /* tp_dealloc */ 0, /* tp_print */ 0, /* tp_getattr */ 0, /* tp_setattr */ 0, /* tp_reserved */ 0, /* tp_repr */ 0, /* tp_as_number */ 0, /* tp_as_sequence */ 0, /* tp_as_mapping */ 0, /* tp_hash */ 0, /* tp_call */ 0, /* tp_str */ pyobject_genericgetattr, /* tp_getattro */ pyobject_genericsetattr, /* tp_setattro */ 0, /* tp_as_buffer */ py_tpflags_default | py_tpflags_basetype, /*tp_flags*/ "pycamera", /* tp_doc */ 0, /* tp_traverse */ 0, /* tp_clear */ 0, /* tp_richcompare */ 0, /* tp_weaklistoffset */ 0, /* tp_iter */ 0, /* tp_iternext */ instance_methods, /* tp_methods */ 0, /* tp_members */ 0, /* tp_getset */ 0, /* tp_base */ 0, /* tp_dict */ 0, /* tp_descr_get */ 0, /* tp_descr_set */ 0, /* tp_dictoffset */ 0, /* tp_init */ 0, /* tp_alloc */ pycamera_new, /* tp_new */};
定义 pycamera 类型,包括其方法、内存分配、释放和其他行为。
pywindow.h
包括
#include <python.h>#include <structmember.h>#include "camerapreview.h"
pywindow 结构体定义
typedef struct{ pyobject_head camerawindow *handler;} pywindow;
定义一个包装 c camerawindow 对象的 pywindow 结构体。 handler 成员指向 camerawindow 的一个实例。
pywindow 对象的方法
窗口实例方法
static pymethoddef window_instance_methods[] = { {"waitkey", waitkey, meth_varargs, null}, {"showframe", showframe, meth_varargs, null}, {"drawcontour", drawcontour, meth_varargs, null}, {"drawtext", drawtext, meth_varargs, null}, {null, null, 0, null}};
定义 pywindow python 对象上可用的方法。
pywindow类型
static pytypeobject pywindowtype = { pyvarobject_head_init(null, 0) "litecam.pywindow", /* tp_name */ sizeof(pywindow), /* tp_basicsize */ 0, /* tp_itemsize */ (destructor)pywindow_dealloc, /* tp_dealloc */ 0, /* tp_print */ 0, /* tp_getattr */ 0, /* tp_setattr */ 0, /* tp_reserved */ 0, /* tp_repr */ 0, /* tp_as_number */ 0, /* tp_as_sequence */ 0, /* tp_as_mapping */ 0, /* tp_hash */ 0, /* tp_call */ 0, /* tp_str */ pyobject_genericgetattr, /* tp_getattro */ pyobject_genericsetattr, /* tp_setattro */ 0, /* tp_as_buffer */ py_tpflags_default | py_tpflags_basetype, /*tp_flags*/ "pywindow", /* tp_doc */ 0, /* tp_traverse */ 0, /* tp_clear */ 0, /* tp_richcompare */ 0, /* tp_weaklistoffset */ 0, /* tp_iter */ 0, /* tp_iternext */ window_instance_methods, /* tp_methods */ 0, /* tp_members */ 0, /* tp_getset */ 0, /* tp_base */ 0, /* tp_dict */ 0, /* tp_descr_get */ 0, /* tp_descr_set */ 0, /* tp_dictoffset */ 0, /* tp_init */ 0, /* tp_alloc */ pywindow_new, /* tp_new */};
定义 pywindow 类型,包括其方法、内存分配、释放和其他行为。
litecam.cpp
#include <python.h>#include <stdio.h>#include "pycamera.h"#include "pywindow.h"#define initerror return nullstatic pyobject *getdevicelist(pyobject *obj, pyobject *args){ pyobject *pylist = pylist_new(0); std::vector<capturedeviceinfo> devices = listcapturedevices(); for (size_t i = 0; i < devices.size(); i++) { capturedeviceinfo &device = devices[i];#ifdef _win32 pyobject *pyname = pyunicode_fromwidechar(device.friendlyname, wcslen(device.friendlyname)); if (pyname != null) { pylist_append(pylist, pyname); py_decref(pyname); }#else pyobject *pyname = pyunicode_fromstring(device.friendlyname); if (pyname != null) { pylist_append(pylist, pyname); py_decref(pyname); }#endif } return pylist;}static pyobject *savejpeg(pyobject *obj, pyobject *args){ const char *filename = null; int width = 0, height = 0; pyobject *bytearray = null; if (!pyarg_parsetuple(args, "siio", &filename, &width, &height, &bytearray)) { pyerr_setstring(pyexc_typeerror, "expected arguments: str, int, int, pybytearray"); return null; } unsigned char *data = (unsigned char *)pybytearray_asstring(bytearray); py_ssize_t size = pybytearray_size(bytearray); if (size != (py_ssize_t)(width * height * 3)) { pyerr_setstring(pyexc_valueerror, "invalid byte array size for the given width and height."); return null; } saveframeasjpeg(data, width, height, filename); py_return_none;}static pymethoddef litecam_methods[] = { {"getdevicelist", getdevicelist, meth_varargs, "get available cameras"}, {"savejpeg", savejpeg, meth_varargs, "get available cameras"}, {null, null, 0, null}};static struct pymoduledef litecam_module_def = { pymoduledef_head_init, "litecam", "internal "litecam" module", -1, litecam_methods};pymodinit_func pyinit_litecam(void){ pyobject *module = pymodule_create(&litecam_module_def); if (module == null) initerror; if (pytype_ready(&pycameratype) < 0) { printf("failed to initialize pycameratype"); py_decref(module); return null; } if (pymodule_addobject(module, "pycamera", (pyobject *)&pycameratype) < 0) { printf("failed to add pycamera to the module"); py_decref(&pycameratype); py_decref(module); initerror; } if (pytype_ready(&pywindowtype) < 0) { printf("failed to initialize pywindowtype"); py_decref(module); return null; } if (pymodule_addobject(module, "pywindow", (pyobject *)&pywindowtype) < 0) { printf("failed to add pywindow to the module"); py_decref(&pywindowtype); py_decref(module); initerror; } return module;}
说明:
构建 python 相机 sdk
实现 python 多条码扫描器的步骤
安装python相机sdk和dynamsoft barcode reader sdk:
pip install lite-camera dynamsoft-capture-vision-bundle
获取 dynamsoft barcode reader 30 天免费试用许可证。
创建用于多条码扫描的 python 脚本:
import litecamfrom dynamsoft_capture_vision_bundle import *import queueclass framefetcher(imagesourceadapter): def has_next_image_to_fetch(self) -> bool: return true def add_frame(self, imagedata): self.add_image_to_buffer(imagedata)class mycapturedresultreceiver(capturedresultreceiver): def __init__(self, result_queue): super().__init__() self.result_queue = result_queue def on_captured_result_received(self, captured_result): self.result_queue.put(captured_result)if __name__ == '__main__': errorcode, errormsg = licensemanager.init_license( "license-key") if errorcode != enumerrorcode.ec_ok and errorcode != enumerrorcode.ec_license_cache_used: print("license initialization failed: errorcode:", errorcode, ", errorstring:", errormsg) else: camera = litecam.pycamera() if camera.open(0): cvr = capturevisionrouter() fetcher = framefetcher() cvr.set_input(fetcher) result_queue = queue.queue() receiver = mycapturedresultreceiver(result_queue) cvr.add_result_receiver(receiver) errorcode, errormsg = cvr.start_capturing( enumpresettemplate.pt_read_barcodes.value) if errorcode != enumerrorcode.ec_ok: print("error:", errormsg) window = litecam.pywindow( camera.getwidth(), camera.getheight(), "camera stream") while window.waitkey('q'): frame = camera.captureframe() if frame is not none: width = frame[0] height = frame[1] size = frame[2] data = frame[3] window.showframe(width, height, data) imagedata = imagedata( bytes(data), width, height, width * 3, enumimagepixelformat.ipf_rgb_888) fetcher.add_frame(imagedata) if not result_queue.empty(): captured_result = result_queue.get_nowait() items = captured_result.get_items() for item in items: if item.get_type() == enumcapturedresultitemtype.crit_barcode: text = item.get_text() location = item.get_location() x1 = location.points[0].x y1 = location.points[0].y x2 = location.points[1].x y2 = location.points[1].y x3 = location.points[2].x y3 = location.points[2].y x4 = location.points[3].x y4 = location.points[3].y contour_points = [ (x1, y1), (x2, y2), (x3, y3), (x4, y4)] window.drawcontour(contour_points) window.drawtext(text, x1, y1, 24, (255, 0, 0)) del location camera.release() cvr.stop_capturing()
将 license-key 替换为您的 dynamsoft barcode reader 许可证密钥。
运行脚本:
python main.py
源代码
https://github.com/yushulx/python-lite-camera