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。
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：
在setup.py中添加以下内容：
from setuptools.command import build_ext
from setuptools import setup, extension
import sys
import os
import io
from setuptools.command.install import install
import shutil
from pathlib import path
lib_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：
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。
#include <python.h> #include <structmember.h> #include "camera.h"
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）”；
pycamera_dealloc
解除分配 camera 对象并释放关联的内存。
pycamera_new
static pyobject *pycamera_new(pytypeobject *type, pyobject *args, pyobject *kwds)
{
pycamera *self;
self = (pycamera *)type->tp_alloc(type, 0);
if (self != null)
{
self->handler = new camera();
}
return (pyobject *)self;
}
创建 pycamera 的新实例。它为python对象分配内存，创建一个新的camera对象，并将其分配给self->handler。
开放
static pyobject *open(pyobject *obj, pyobject *args)
{
pycamera *self = (pycamera *)obj;
int index = 0;
if (!pyarg_parsetuple(args, "i", &index))
{
return null;
}
bool ret = self->handler->open(index);
return py_buildvalue("i", ret);
}
打开指定索引的相机。
列表媒体类型
static pyobject *listmediatypes(pyobject *obj, pyobject *args)
{
pycamera *self = (pycamera *)obj;
std::vector<mediatypeinfo> mediatypes = self->handler->listsupportedmediatypes();
pyobject *pylist = pylist_new(0);
for (size_t i = 0; i < mediatypes.size(); i++)
{
mediatypeinfo &mediatype = mediatypes[i];
#ifdef _win32
pyobject *subtypename = pyunicode_fromwidechar(mediatype.subtypename, wcslen(mediatype.subtypename));
pyobject *pymediatype = py_buildvalue("{s:i,s:i,s:o}",
"width", mediatype.width,
"height", mediatype.height,
"subtypename", subtypename);
if (subtypename != null)
{
py_decref(subtypename);
}
#else
pyobject *pymediatype = py_buildvalue("{s:i,s:i,s:s}",
"width", mediatype.width,
"height", mediatype.height,
"subtypename", mediatype.subtypename);
#endif
pylist_append(pylist, pymediatype);
}
return pylist;
}
返回支持的媒体类型列表。对于 windows，它将宽字符串转换为 python unicode 对象。
发布
static pyobject *release(pyobject *obj, pyobject *args)
{
pycamera *self = (pycamera *)obj;
self->handler->release();
py_return_none;
}
释放相机。
设置分辨率
static pyobject *setresolution(pyobject *obj, pyobject *args)
{
pycamera *self = (pycamera *)obj;
int width = 0, height = 0;
if (!pyarg_parsetuple(args, "ii", &width, &height))
{
return null;
}
int ret = self->handler->setresolution(width, height);
return py_buildvalue("i", ret);
}
设置相机的分辨率。
捕获帧
static pyobject *captureframe(pyobject *obj, pyobject *args)
{
pycamera *self = (pycamera *)obj;
framedata frame = self->handler->captureframe();
if (frame.rgbdata)
{
pyobject *rgbdata = pybytearray_fromstringandsize((const char *)frame.rgbdata, frame.size);
pyobject *pyframe = py_buildvalue("iiio", frame.width, frame.height, frame.size, rgbdata);
releaseframe(frame);
return pyframe;
}
else
{
py_return_none;
}
}
从相机捕获帧并将 rgb 数据作为 python 字节数组返回。
getwidth 和 getheight
static pyobject *getwidth(pyobject *obj, pyobject *args)
{
pycamera *self = (pycamera *)obj;
int width = self->handler->framewidth;
return py_buildvalue("i", width);
}
static pyobject *getheight(pyobject *obj, pyobject *args)
{
pycamera *self = (pycamera *)obj;
int height = self->handler->frameheight;
return py_buildvalue("i", height);
}
返回捕获帧的宽度和高度。
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。
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。
#include <python.h> #include <structmember.h> #include "camerapreview.h"
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_dealloc
static int pywindow_clear(pywindow *self)
{
if (self->handler)
{
delete self->handler;
}
return 0;
}
static void pywindow_dealloc(pywindow *self)
{
pywindow_clear(self);
py_type(self)->tp_free((pyobject *)self);
}
取消分配camerawindow对象并释放内存。
pywindow_new
static pyobject *pywindow_new(pytypeobject *type, pyobject *args, pyobject *kwds)
{
pywindow *self;
int width = 0, height = 0;
char *title = null;
if (!pyarg_parsetuple(args, "iis", &width, &height, &title))
{
return null;
}
self = (pywindow *)type->tp_alloc(type, 0);
if (self != null)
{
self->handler = new camerawindow(width, height, title);
if (!self->handler->create())
{
std::cerr << "failed to create window." << std::endl;
return null;
}
self->handler->show();
}
return (pyobject *)self;
}
创建 pywindow 的新实例。它为python对象分配内存，创建一个新的camerawindow对象，并将其分配给self->handler。
等待键
static pyobject *waitkey(pyobject *obj, pyobject *args)
{
pywindow *self = (pywindow *)obj;
const char *key = null;
if (!pyarg_parsetuple(args, "s", &key) || strlen(key) != 1)
{
pyerr_setstring(pyexc_valueerror, "expected a single character string");
return null;
}
bool ret = self->handler->waitkey(key[0]);
return py_buildvalue("i", ret);
}
等待按键事件，如果按键与指定字符匹配则返回 false。 false 意味着应用程序应该退出。
showframe
static pyobject *showframe(pyobject *obj, pyobject *args)
{
pywindow *self = (pywindow *)obj;
int width = 0, height = 0;
pyobject *bytearray = null;
if (!pyarg_parsetuple(args, "iio", &width, &height, &bytearray))
{
return null;
}
unsigned char *data = (unsigned char *)pybytearray_asstring(bytearray);
self->handler->showframe(data, width, height);
py_return_none;
}
在窗口中显示一个框架。
绘制轮廓
static pyobject *drawcontour(pyobject *obj, pyobject *args)
{
pywindow *self = (pywindow *)obj;
pyobject *pypoints = null;
if (!pyarg_parsetuple(args, "o", &pypoints))
{
return null;
}
std::vector<std::pair<int, int>> points;
for (py_ssize_t i = 0; i < pylist_size(pypoints); i++)
{
pyobject *item = pylist_getitem(pypoints, i);
int x = pylong_aslong(pytuple_getitem(item, 0));
int y = pylong_aslong(pytuple_getitem(item, 1));
points.push_back(std::make_pair(x, y));
}
self->handler->drawcontour(points);
py_return_none;
}
在框架上绘制轮廓（一系列点）。
绘制文本
static pyobject *drawtext(pyobject *obj, pyobject *args)
{
pywindow *self = (pywindow *)obj;
const char *text = null;
int x = 0, y = 0, fontsize = 0;
pyobject *pycolor = null;
if (!pyarg_parsetuple(args, "siiio", &text, &x, &y, &fontsize, &pycolor))
{
return null;
}
camerawindow::color color;
color.r = (unsigned char)pylong_aslong(pytuple_getitem(pycolor, 0));
color.g = (unsigned char)pylong_aslong(pytuple_getitem(pycolor, 1));
color.b = (unsigned char)pylong_aslong(pytuple_getitem(pycolor, 2));
self->handler->drawtext(text, x, y, fontsize, color);
py_return_none;
}
在框架上绘制文本。
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。
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。
#include <python.h>
#include <stdio.h>
#include "pycamera.h"
#include "pywindow.h"
#define initerror return null
static 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\n");
py_decref(module);
return null;
}
if (pymodule_addobject(module, "pycamera", (pyobject *)&pycameratype) < 0)
{
printf("failed to add pycamera to the module\n");
py_decref(&pycameratype);
py_decref(module);
initerror;
}
if (pytype_ready(&pywindowtype) < 0)
{
printf("failed to initialize pywindowtype\n");
py_decref(module);
return null;
}
if (pymodule_addobject(module, "pywindow", (pyobject *)&pywindowtype) < 0)
{
printf("failed to add pywindow to the module\n");
py_decref(&pywindowtype);
py_decref(module);
initerror;
}
return module;
}
说明：
开发模式
python setup.py develop
轮组
python setup.py bdist_wheel
来源分布
python setup.py sdist
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 litecam
from dynamsoft_capture_vision_bundle import *
import queue
class 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
https://github.com/yushulx/python-lite-camera
以上就是构建 Python 相机 SDK 并使用它进行多条码扫描的详细内容，更多请关注php中文网其它相关文章！
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