Question

我正在尝试修改我的Pipsta打印机提供的简单python脚本，这样就不会打印单行文本，而是打印出一系列内容。

我知道有更好的方法可以做到这一点，但是使用下面的脚本，有人可以告诉我需要围绕脚本的“txt =”部分做出哪些更改，以便我可以打印列出项目而不仅仅是一个项目？感谢。

# 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()

Answer 1

Pipsta使用linux换行符（'\ n'，0x0A，十进制10）来标记新行。如需快速测试更改BasicPrint.py，请执行以下操作：

#txt = parse_arguments()
txt = 'Recipt:\n========\n1. food 1 - 100$\n2. drink 1 - 200$\n\n\n\n\n'

usb_endpoint.write(b'\x1b!\x00')

for x in txt:
    usb_endpoint.write(x)
    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)

我注释掉了参数解析并注入了一个包含多行内容的测试字符串。

Pipsta打印机和打印列表

1 个答案: