1
我正在嘗試修改Pipsta打印機附帶的簡單python腳本，以便打印出單行文本而不是打印單行文本。Pipsta打印機和打印列表
我知道可能有更好的方法來做到這一點，但是使用下面的腳本，有人可以告訴我在腳本的「txt =」部分需要做些什麼修改，以便我可以列出一個列表的項目，而不只是一個項目？ 謝謝。
# BasicPrint.py
# Copyright (c) 2014 Able Systems Limited. All rights reserved.
'''This simple code example is provided as-is, and is for demonstration
purposes only. Able Systems takes no responsibility for any system
implementations based on this code.
This very simple python script establishes USB communication with the Pipsta
printer sends a simple text string to the printer.
Copyright (c) 2014 Able Systems Limited. All rights reserved.
'''
import argparse
import platform
import sys
import time
import usb.core
import usb.util
FEED_PAST_CUTTER = b'\n' * 5
USB_BUSY = 66
# NOTE: The following section establishes communication to the Pipsta printer
# via USB. YOU DO NOT NEED TO UNDERSTAND THIS SECTION TO PROGRESS WITH THE
# TUTORIALS! ALTERING THIS SECTION IN ANY WAY CAN CAUSE A FAILURE TO COMMUNICATE
# WITH THE PIPSTA. If you are interested in learning about what is happening
# herein, please look at the following references:
#
# PyUSB: http://sourceforge.net/apps/trac/pyusb/
# ...which is a wrapper for...
# LibUSB: http://www.libusb.org/
#
# For full help on PyUSB, at the IDLE prompt, type:
# >>> import usb
# >>> help(usb)
# 'Deeper' help can be trawled by (e.g.):
# >>> help(usb.core)
#
# or at the Linux prompt, type:
# pydoc usb
# pydoc usb.core
PIPSTA_USB_VENDOR_ID = 0x0483
PIPSTA_USB_PRODUCT_ID = 0xA053
def parse_arguments():
'''Parse the arguments passed to the script looking for a font file name
and a text string to print. If either are mssing defaults are used.
'''
txt = 'Hello World from Pipsta!'
parser = argparse.ArgumentParser()
parser.add_argument('text', help='the text to print',
nargs='*', default=txt.split())
args = parser.parse_args()
return ' '.join(args.text)
def main():
"""The main loop of the application. Wrapping the code in a function
prevents it being executed when various tools import the code.
"""
if platform.system() != 'Linux':
sys.exit('This script has only been written for Linux')
# Find the Pipsta's specific Vendor ID and Product ID
dev = usb.core.find(idVendor=PIPSTA_USB_VENDOR_ID,
idProduct=PIPSTA_USB_PRODUCT_ID)
if dev is None: # if no such device is connected...
raise IOError('Printer not found') # ...report error
try:
# Linux requires USB devices to be reset before configuring, may not be
# required on other operating systems.
dev.reset()
# Initialisation. Passing no arguments sets the configuration to the
# currently active configuration.
dev.set_configuration()
except usb.core.USBError as ex:
raise IOError('Failed to configure the printer', ex)
# The following steps get an 'Endpoint instance'. It uses
# PyUSB's versatile find_descriptor functionality to claim
# the interface and get a handle to the endpoint
# An introduction to this (forming the basis of the code below)
# can be found at:
cfg = dev.get_active_configuration() # Get a handle to the active interface
interface_number = cfg[(0, 0)].bInterfaceNumber
# added to silence Linux complaint about unclaimed interface, it should be
# release automatically
usb.util.claim_interface(dev, interface_number)
alternate_setting = usb.control.get_interface(dev, interface_number)
interface = usb.util.find_descriptor(
cfg, bInterfaceNumber=interface_number,
bAlternateSetting=alternate_setting)
usb_endpoint = usb.util.find_descriptor(
interface,
custom_match=lambda e:
usb.util.endpoint_direction(e.bEndpointAddress) ==
usb.util.ENDPOINT_OUT
)
if usb_endpoint is None: # check we have a real endpoint handle
raise IOError("Could not find an endpoint to print to")
# Now that the USB endpoint is open, we can start to send data to the
# printer.
# The following opens the text_file, by using the 'with' statemnent there is
# no need to close the text_file manually. This method ensures that the
# close is called in all situation (including unhandled exceptions).
txt = parse_arguments()
usb_endpoint.write(b'\x1b!\x00')
# Print a char at a time and check the printers buffer isn't full
for x in txt:
usb_endpoint.write(x) # write all the data to the USB OUT endpoint
res = dev.ctrl_transfer(0xC0, 0x0E, 0x020E, 0, 2)
while res[0] == USB_BUSY:
time.sleep(0.01)
res = dev.ctrl_transfer(0xC0, 0x0E, 0x020E, 0, 2)
usb_endpoint.write(FEED_PAST_CUTTER)
usb.util.dispose_resources(dev)
# Ensure that BasicPrint is ran in a stand-alone fashion (as intended) and not
# imported as a module. Prevents accidental execution of code.
if __name__ == '__main__':
main()