Windows11下用brother_ql库打印图片报错：Operation not supported

在Windows 11系统中，尝试使用Python的brother_ql库为Brother QL-560打印机打印图片，已完成以下配置：

• 安装libusb-1.0.20，将MS64/dll添加到PATH变量，并把libusb-1.0.dll复制到System32目录
• Brother QL-560已安装官方驱动，可在P-Touch Editor中正常打印

使用的代码如下：

from PIL import Image
from brother_ql.conversion import convert
from brother_ql.backends.helpers import send, discover
from brother_ql.raster import BrotherQLRaster
import logging

logging.basicConfig(level=logging.DEBUG)

image = Image.open(r'.\screenshot.png')
size = (720, 1008)
image = image.resize(size)

backend = 'pyusb'
#find printer
#print(discover(backend))
printer = 'usb://0x04f9:0x2027'
model = 'QL-560'

qlr = BrotherQLRaster(model)
qlr.exception_on_warning = True

instructions = convert(
        qlr=qlr, 
        images=[image],
        label='62', 
        rotate='90',    # 'Auto', '0', '90', '270'
        threshold=70.0,    # Black and white threshold in percent.
        dither=False, 
        compress=False, 
        dpi_600=False, 
        hq=True,
        cut=True
)

send(instructions=instructions, printer_identifier=printer, backend_identifier=backend, blocking=True)

运行代码后抛出错误：

deprecation warning: brother_ql.devicedependent is deprecated and will be removed in a future release
WARNING:brother_ql.conversion:Need to resize the image...
DEBUG:brother_ql.raster:raster_image_size: 720x497
Traceback (most recent call last):
  File "C:\Users\User\PycharmProjects\labelCreator\listUSB.py", line 42, in <module>
    send(instructions=instructions, printer_identifier=printer, backend_identifier=backend, blocking=True)
  File "C:\Users\User\PycharmProjects\labelCreator\venv\lib\site-packages\brother_ql\backends\helpers.py", line 57, in send
    printer = BrotherQLBackend(printer_identifier)
  File "C:\Users\User\PycharmProjects\labelCreator\venv\lib\site-packages\brother_ql\backends\pyusb.py", line 101, in __init__
    self.dev.set_configuration()
  File "C:\Users\User\PycharmProjects\labelCreator\venv\lib\site-packages\usb\core.py", line 915, in set_configuration
    self._ctx.managed_set_configuration(self, configuration)
  File "C:\Users\User\PycharmProjects\labelCreator\venv\lib\site-packages\usb\core.py", line 113, in wrapper
    return f(self, *args, **kwargs)
  File "C:\Users\User\PycharmProjects\labelCreator\venv\lib\site-packages\usb\core.py", line 158, in managed_set_configuration
    self.managed_open()
  File "C:\Users\User\PycharmProjects\labelCreator\venv\lib\site-packages\usb\core.py", line 113, in wrapper
    return f(self, *args, **kwargs)
  File "C:\Users\User\PycharmProjects\labelCreator\venv\lib\site-packages\usb\core.py", line 131, in managed_open
    self.handle = self.backend.open_device(self.dev)
  File "C:\Users\User\PycharmProjects\labelCreator\venv\lib\site-packages\usb\backend\libusb1.py", line 804, in open_device
    return _DeviceHandle(dev)
  File "C:\Users\User\PycharmProjects\labelCreator\venv\lib\site-packages\usb\backend\libusb1.py", line 652, in __init__
    _check(_lib.libusb_open(self.devid, byref(self.handle)))
  File "C:\Users\User\PycharmProjects\labelCreator\venv\lib\site-packages\usb\backend\libusb1.py", line 600, in _check
    raise NotImplementedError(_strerror(ret))
NotImplementedError: Operation not supported or unimplemented on this platform

Process finished with exit code 1

疑问：遗漏了什么配置？是否存在驱动不兼容的问题？

这个错误的核心原因是Windows系统中，官方打印机驱动已占用USB设备，导致libusb/pyusb无法获取设备访问权限，以下是两种可行的解决途径：

途径1：改用Windows专属Backend（推荐） #

brother_ql库提供了针对Windows的原生backend，无需依赖libusb，直接修改代码即可：

1. 将代码中的backend = 'pyusb'改为backend = 'windows'
2. 取消注释print(discover(backend))这一行，运行代码获取正确的打印机标识符（可能是类似'usb://0x04f9:0x2027'或者打印机的系统显示名称）
3. 将获取到的标识符替换到printer变量中，重新运行代码

途径2：替换打印机驱动为libusb兼容版本（需权衡） #

如果坚持使用pyusb backend，需要将官方驱动替换为libusb-win32：

• 使用Zadig工具，找到Brother QL-560设备，将其驱动替换为libusb-win32
• 注意：替换后官方P-Touch Editor将无法使用该打印机，若需要恢复，需在设备管理器中手动换回官方驱动

额外代码优化建议 #

• 无需手动resize图片，convert函数会根据标签尺寸自动调整，可删除手动resize的代码行，避免尺寸不匹配的警告
• 保持qlr.exception_on_warning = True，便于及时发现配置问题

内容的提问来源于stack exchange，提问作者Glaux De