50c627fbb0
On a RaspberryPi it's taking 10 seconds to simply run: import escpos.printer This change creates a pickle file that will load 20x faster. The rationale is that the capabilities.json file doesn't change too often. Also changed some imports for PEP8.
151 lines
4.0 KiB
Python
151 lines
4.0 KiB
Python
import re
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from os import environ, path
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import pickle
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import logging
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import time
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import six
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import yaml
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logging.basicConfig()
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logger = logging.getLogger(__name__)
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pickle_dir = environ.get('ESCPOS_CAPABILITIES_PICKLE_DIR', '/tmp/')
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pickle_path = path.join(pickle_dir, 'capabilities.pickle')
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capabilities_path = environ.get(
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'ESCPOS_CAPABILITIES_FILE',
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path.join(path.dirname(__file__), 'capabilities.json'))
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# Load external printer database
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t0 = time.time()
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logger.debug('Using capabilities from file: %s', capabilities_path)
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if path.exists(pickle_path):
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if path.getmtime(capabilities_path) > path.getmtime(pickle_path):
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logger.debug('Found a more recent capabilities file')
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full_load = True
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else:
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full_load = False
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logger.debug('Loading capabilities from pickle in %s', pickle_path)
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with open(pickle_path, 'rb') as cf:
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CAPABILITIES = pickle.load(cf)
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else:
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logger.debug('Capabilities pickle file not found: %s', pickle_path)
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full_load = True
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if full_load:
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logger.debug('Loading and pickling capabilities')
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with open(capabilities_path) as cp, open(pickle_path, 'wb') as pp:
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CAPABILITIES = yaml.load(cp)
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pickle.dump(CAPABILITIES, pp)
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logger.debug('Finished loading capabilities took %.2fs', time.time() - t0)
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PROFILES = CAPABILITIES['profiles']
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class NotSupported(Exception):
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"""Raised if a requested feature is not suppored by the
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printer profile.
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"""
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pass
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BARCODE_B = 'barcodeB'
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class BaseProfile(object):
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"""This respresents a printer profile.
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A printer profile knows about the number of columns, supported
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features, colors and more.
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"""
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profile_data = {}
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def __getattr__(self, name):
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return self.profile_data[name]
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def get_font(self, font):
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"""Return the escpos index for `font`. Makes sure that
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the requested `font` is valid.
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"""
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font = {'a': 0, 'b': 1}.get(font, font)
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if not six.text_type(font) in self.fonts:
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raise NotSupported(
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'"{}" is not a valid font in the current profile'.format(font))
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return font
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def get_columns(self, font):
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""" Return the number of columns for the given font.
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"""
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font = self.get_font(font)
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return self.fonts[six.text_type(font)]['columns']
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def supports(self, feature):
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"""Return true/false for the given feature.
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"""
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return self.features.get(feature)
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def get_code_pages(self):
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"""Return the support code pages as a {name: index} dict.
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"""
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return {v: k for k, v in self.codePages.items()}
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def get_profile(name=None, **kwargs):
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"""Get the profile by name; if no name is given, return the
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default profile.
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"""
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if isinstance(name, Profile):
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return name
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clazz = get_profile_class(name or 'default')
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return clazz(**kwargs)
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CLASS_CACHE = {}
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def get_profile_class(name):
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"""For the given profile name, load the data from the external
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database, then generate dynamically a class.
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"""
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if name not in CLASS_CACHE:
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profile_data = PROFILES[name]
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profile_name = clean(name)
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class_name = '{}{}Profile'.format(
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profile_name[0].upper(), profile_name[1:])
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new_class = type(class_name, (BaseProfile,), {'profile_data': profile_data})
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CLASS_CACHE[name] = new_class
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return CLASS_CACHE[name]
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def clean(s):
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# Remove invalid characters
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s = re.sub('[^0-9a-zA-Z_]', '', s)
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# Remove leading characters until we find a letter or underscore
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s = re.sub('^[^a-zA-Z_]+', '', s)
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return str(s)
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class Profile(get_profile_class('default')):
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"""
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For users, who want to provide their profile
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"""
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def __init__(self, columns=None, features=None):
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super(Profile, self).__init__()
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self.columns = columns
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self.features = features or {}
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def get_columns(self, font):
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if self.columns is not None:
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return self.columns
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return super(Profile, self).get_columns(font)
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