python-escpos/src/escpos/capabilities.py

152 lines
4.1 KiB
Python

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