Update the way a printer is found, update the configuration of Brother
Printers
This commit is contained in:
n07070
@@ -7,6 +7,7 @@ the methods expected from printers.
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from collections.abc import Set
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import time
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import threading
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import usb.core
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import usb.util
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from printer import Printer, EscPosPrinter, BrotherPrinter
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@@ -19,10 +20,11 @@ class Printers:
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def __init__(self, app):
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"""
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Discover printers connected to the computer and return a Collection of Printer()
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Discovers printers connected to the computer
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"""
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self.app = app
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self.printers = self._discover_printers()
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self.printers = list(self._discover_printers())
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self._lock = threading.Lock()
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def _discover_printers(self) -> Set[Printer]:
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"""
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@@ -40,25 +42,36 @@ class Printers:
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printers = set()
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# Find all connected USB devices
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devices = usb.core.find(find_all=True, custom_match=_FindClass(7))
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waiting_time_for_printer = 10
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while not list(devices):
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self.app.logger.warning(str(waiting_time_for_printer) + " Found no printers, waiting for a printer to connect to the system...")
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time.sleep(1)
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waiting_time_for_printer = waiting_time_for_printer - 1
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devices = usb.core.find(find_all=True, custom_match=_FindClass(7))
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if waiting_time_for_printer == 0:
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# TODO : this could go in the config ?
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waiting_time_for_printer = 5
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while True:
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# Find all connected USB devices
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# the find() fnc returns a generator
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devices = list(
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usb.core.find(
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find_all=True,
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custom_match=_FindClass(self.app,7)
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)
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)
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if devices:
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break
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if waiting_time_for_printer <= 0:
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self.app.logger.warning(
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"No USB devices of class 7 ( printers ) found or pyusb could not access the bus."
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)
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raise RuntimeError(
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"No USB devices of class 7 ( printers ) found or pyusb could not access the bus."
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)
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if not list(devices):
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self.app.logger.warning(
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"No USB devices of class 7 ( printers ) found or pyusb could not access the bus."
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)
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raise RuntimeError(
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"No USB devices of class 7 ( printers ) found or pyusb could not access the bus."
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)
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"No printers found; waiting for a printer to connect..."
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)
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time.sleep(1)
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waiting_time_for_printer -= 1
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for dev in devices:
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# Attempt to get the manufacturer and product strings
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@@ -107,8 +120,7 @@ class Printers:
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self.app.logger.debug("Trying to create a new BROTHER printer")
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brother_printer = BrotherPrinter(
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self.app, vendor_id=dev.idVendor, device_id=dev.idProduct
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)
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self.app, vendor_id=dev.idVendor, device_id=dev.idProduct)
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except Exception as e:
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self.app.logger.error(
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"Could not create a %s printer class with %s:%s" , product,
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@@ -129,43 +141,45 @@ class Printers:
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return printers
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def any(self) -> Printer:
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"""
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Return a dict key: UUID, value: Printer, with any connected printer.
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"""
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if len(self.printers) > 0:
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for i in self.printers:
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return i
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else:
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raise RuntimeError("No printers available")
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def acquire_available_printer(self, start_index=0):
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"""Atomically acquire and return an available printer, or None."""
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printers = self.printers
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if not printers:
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self.app.logger.error("No printers available for acquisition")
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return None
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# def get_printer(self, printer_type):
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# """
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# Return a specific printer
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with self._lock:
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for offset in range(len(printers)):
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index = (start_index + offset) % len(printers)
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printer = printers[index]
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# printer_type -- a printer type
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# """
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# return NotImplementedError()
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if not printer.used:
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printer.use_printer()
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return index, printer
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return None
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class _FindClass:
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"""
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Use by usb.core to modify the way USB devices are found
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Taken from pyUSB documentation on Github
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"""
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def __init__(self, class_):
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def __init__(self, app, class_):
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self._class = class_
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self.app = app
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def __call__(self, device):
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# first, let's check the device
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self.app.logger.debug("Found a USB device of class %s", str(device.bDeviceClass))
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if device.bDeviceClass == self._class:
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return True
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# ok, transverse all devices to find an
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# interface that matches our class
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for cfg in device:
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# find_descriptor: what's it?
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intf = usb.util.find_descriptor(cfg, bInterfaceClass=self._class)
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if intf is not None:
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for configuration in device:
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# Every device can have one or more configuration,
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interface = usb.util.find_descriptor(configuration, bInterfaceClass=self._class)
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# each config can have several interfaces
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if interface is not None:
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return True
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return False
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