Merge pull request #266 from python-escpos/development

release v3.0a3

.mailmap

@@ -9,3 +9,4 @@ Renato Lorenzi <renato.lorenzi@senior.com.br>        Renato.Lorenzi <renato.lore
 Ahmed Tahri <nyuubi.10@gmail.com>                    TAHRI Ahmed <nyuubi.10@gmail.com>
 Michael Elsdörfer <michael@elsdoerfer.com>           Michael Elsdörfer <michael@elsdoerfer.info>
 csoft2k <csoft2k@hotmail.com>
+Sergio Pulgarin <sergio.pulgarin@gmail.com>

AUTHORS

@@ -12,15 +12,18 @@ Hark
 Joel Lehtonen
 Kristi
 ldos
+Lucy Linder
 Manuel F Martinez
 Michael Billington
 Michael Elsdörfer
+mrwunderbar666
 Nathan Bookham
 Patrick Kanzler
 Qian Linfeng
 Renato Lorenzi
 Romain Porte
 Sam Cheng
+Sergio Pulgarin
 Stephan Sokolow
 Thijs Triemstra
 Thomas van den Berg

CHANGELOG.rst

@@ -1,6 +1,55 @@
 *********
 Changelog
 *********
+2017-10-08 - Version 3.0a3 - "Just Testing"
+-------------------------------------------
+This release is the fourth alpha release of the new version 3.0. Please
+be aware that the API will still change until v3.0 is released.
+
+changes
+^^^^^^^
+- minor changes in documentation, tests and examples
+- pickle capabilities for faster startup
+- first implementation of centering images and QR
+- check barcodes based on regex
+
+contributors
+^^^^^^^^^^^^
+- Patrick Kanzler
+- Lucy Linder
+- Romain Porte
+- Sergio Pulgarin
+
+2017-08-04 - Version 3.0a2 - "It's My Party And I'll Sing If I Want To"
+-----------------------------------------------------------------------
+This release is the third alpha release of the new version 3.0. Please
+be aware that the API will still change until v3.0 is released.
+
+changes
+^^^^^^^
+- refactor of the set-method
+- preliminary support of POS "line display" printing
+- improvement of tests
+- added ImageWidthError
+- list authors in repository
+- add support for software-based barcode-rendering
+- fix SerialException when trying to close device on __del__
+- added the DLE EOT querying command for USB and Serial
+- ensure QR codes have a large enough border
+- make feed for cut optional
+- fix the behavior of horizontal tabs
+- added test script for hard an soft barcodes
+- implemented paper sensor querying command
+- added weather forecast example script
+- added a method for simpler newlines
+
+contributors
+^^^^^^^^^^^^
+- csoft2k
+- Patrick Kanzler
+- mrwunderbar666
+- Romain Porte
+- Ahmed Tahri
 
 2017-03-29 - Version 3.0a1 - "Headcrash"
 ----------------------------------------

CONTRIBUTING.rst

@@ -20,6 +20,7 @@ When contributing the first time, please include a commit with the output of thi
 Otherwise the integration-check will fail.
 
 When you change your username or mail-address, please also update the `.mailmap` and the authors-list.
+You can find a good documentation on the mapping-feature in the `documentation of git-shortlog <https://git-scm.com/docs/git-shortlog#_mapping_authors>`_.
 
 Style-Guide
 -----------
@@ -47,9 +48,11 @@ Often you can achieve compatibility quite easily with a tool from the `six`-pack
 
 PEP8
 ^^^^
-This is not yet consequently done in every piece of code, but please try to ensure
-that your code honors PEP8.
-The checks by Landscape and QuantifiedCode that run on every PR will provide you with hints.
+The entire codebase adheres to the rules of PEP8.
+These rules are enforced by running `flake8` in the integration-checks.
+Please adhere to these rules as your contribution can only be merged if the check succeeds.
+You can use flake8 or similar tools locally in order to check your code.
+Apart from that the travis-log and the check by Landscape will provide you with hints.
 
 GIT
 ^^^

README.rst

@@ -6,10 +6,6 @@ python-escpos - Python library to manipulate ESC/POS Printers
     :target: https://travis-ci.org/python-escpos/python-escpos
     :alt: Continous Integration
 
-.. image:: https://www.quantifiedcode.com/api/v1/project/95748b89a3974700800b85e4ed3d32c4/badge.svg
-    :target: https://www.quantifiedcode.com/app/project/95748b89a3974700800b85e4ed3d32c4
-    :alt: Code issues
-
 .. image:: https://landscape.io/github/python-escpos/python-escpos/master/landscape.svg?style=flat
     :target: https://landscape.io/github/python-escpos/python-escpos/master
     :alt: Code Health
@@ -74,4 +70,13 @@ The full project-documentation is available on `Read the Docs <https://python-es
 Contributing
 ------------
 
-This project is open for any contribution! Please see CONTRIBUTING.rst for more information.
+This project is open for any contribution! Please see `CONTRIBUTING.rst <http://python-escpos.readthedocs.io/en/latest/dev/contributing.html>`_ for more information.
+
+
+Disclaimer
+----------
+
+None of the vendors cited in this project agree or endorse any of the patterns or implementations.
+Its names are used only to maintain context.
+
+

doc/generate_authors.sh

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-GENLIST=$(git shortlog -s -n | cut -f2 | sort)
+GENLIST=$(git shortlog -s -n | cut -f2 | sort -f)
 AUTHORSFILE="$(dirname $0)/../AUTHORS"
 TEMPAUTHORSFILE="/tmp/python-escpos-authorsfile"
 

doc/requirements.txt

@@ -5,3 +5,4 @@ pyserial
 sphinx-rtd-theme
 setuptools-scm
 docutils>=0.12
+viivakoodi

examples/barcodes.py

@@ -0,0 +1,11 @@
+from escpos.printer import Usb
+
+
+# Adapt to your needs
+p = Usb(0x0416, 0x5011, profile="POS-5890")
+
+# Print software and then hardware barcode with the same content
+p.soft_barcode('code39', '123456')
+p.text('\n')
+p.text('\n')
+p.barcode('123456', 'CODE39')

examples/codepage_tables.py

@@ -37,14 +37,14 @@ def print_codepage(printer, codepage):
     sep = ""
 
     # Table header
-    printer.set(text_type='B')
+    printer.set(font='b')
     printer._raw("  {}\n".format(sep.join(map(lambda s: hex(s)[2:], range(0, 16)))))
     printer.set()
 
     # The table
     for x in range(0, 16):
         # First column
-        printer.set(text_type='B')
+        printer.set(font='b')
         printer._raw("{} ".format(hex(x)[2:]))
         printer.set()
 

examples/graphics/climacons/readme.md

@@ -0,0 +1,10 @@
+# Climacons by Adam Whitcroft
+
+75 climatically categorised pictographs for web and UI design by [@adamwhitcroft](http://www.twitter.com/#!/adamwhitcroft).
+
+Visit the [Climacons](http://adamwhitcroft.com/climacons/) website for more information.
+
+Visit [Adam Whitcroft on GitHub](https://github.com/AdamWhitcroft)
+
+## License
+You are free to use any of the Climacons Icons (the "icons") in any personal or commercial work without obligation of payment (monetary or otherwise) or attribution, however a credit for the work would be appreciated. **Do not** redistribute or sell and **do not** claim creative credit. Intellectual property rights are not transferred with the download of the icons.

examples/qr_code.py

@@ -16,4 +16,4 @@ if __name__ == '__main__':
 
     # Adapt to your needs
     p = Usb(0x0416, 0x5011, profile="POS-5890")
-    p.qr(content)
+    p.qr(content, center=True)

examples/weather.py

@@ -0,0 +1,127 @@
+#!/usr/bin/python
+
+
+# Adapted script from Adafruit
+# Weather forecast for Raspberry Pi w/Adafruit Mini Thermal Printer.
+# Retrieves data from DarkSky.net's API, prints current conditions and
+# forecasts for next two days.
+# Weather example using nice bitmaps.
+# Written by Adafruit Industries.  MIT license.
+# Adapted and enhanced for escpos library by MrWunderbar666
+
+# Icons taken from http://adamwhitcroft.com/climacons/
+# Check out his github: https://github.com/AdamWhitcroft/climacons
+
+
+from __future__ import print_function
+from datetime import datetime
+import calendar
+import urllib
+import json
+import time
+import os
+
+from escpos.printer import Usb
+
+""" Setting up the main pathing """
+this_dir, this_filename = os.path.split(__file__)
+GRAPHICS_PATH = os.path.join(this_dir, "graphics/climacons/")
+
+# Adapt to your needs
+printer = Usb(0x0416, 0x5011, profile="POS-5890")
+
+# You can get your API Key on www.darksky.net and register a dev account.
+# Technically you can use any other weather service, of course :)
+API_KEY = "YOUR API KEY"
+
+LAT = "22.345490"       # Your Location
+LONG = "114.189945"     # Your Location
+
+
+def forecast_icon(idx):
+    icon = data['daily']['data'][idx]['icon']
+    image = GRAPHICS_PATH + icon + ".png"
+    return image
+
+
+# Dumps one forecast line to the printer
+def forecast(idx):
+    date = datetime.fromtimestamp(int(data['daily']['data'][idx]['time']))
+    day = calendar.day_name[date.weekday()]
+    lo = data['daily']['data'][idx]['temperatureMin']
+    hi = data['daily']['data'][idx]['temperatureMax']
+    cond = data['daily']['data'][idx]['summary']
+    print(date)
+    print(day)
+    print(lo)
+    print(hi)
+    print(cond)
+    time.sleep(1)
+    printer.set(
+        font='a',
+        height=2,
+        align='left',
+        bold=False,
+        double_height=False)
+    printer.text(day + ' \n ')
+    time.sleep(5)           # Sleep to prevent printer buffer overflow
+    printer.text('\n')
+    printer.image(forecast_icon(idx))
+    printer.text('low ' + str(lo))
+    printer.text(deg)
+    printer.text('\n')
+    printer.text(' high ' + str(hi))
+    printer.text(deg)
+    printer.text('\n')
+    # take care of pesky unicode dash
+    printer.text(cond.replace(u'\u2013', '-').encode('utf-8'))
+    printer.text('\n \n')
+
+
+def icon():
+    icon = data['currently']['icon']
+    image = GRAPHICS_PATH + icon + ".png"
+    return image
+
+
+deg = ' C'      # Degree symbol on thermal printer, need to find a better way to use a proper degree symbol
+
+# if you want Fahrenheit change units= to 'us'
+url = "https://api.darksky.net/forecast/" + API_KEY + "/" + LAT + "," + LONG + \
+    "?exclude=[alerts,minutely,hourly,flags]&units=si"  # change last bit to 'us' for Fahrenheit
+response = urllib.urlopen(url)
+data = json.loads(response.read())
+
+printer.print_and_feed(n=1)
+printer.control("LF")
+printer.set(font='a', height=2, align='center', bold=True, double_height=True)
+printer.text("Weather Forecast")
+printer.text("\n")
+printer.set(align='center')
+
+
+# Print current conditions
+printer.set(font='a', height=2, align='center', bold=True, double_height=False)
+printer.text('Current conditions: \n')
+printer.image(icon())
+printer.text("\n")
+
+printer.set(font='a', height=2, align='left', bold=False, double_height=False)
+temp = data['currently']['temperature']
+cond = data['currently']['summary']
+printer.text(temp)
+printer.text(' ')
+printer.text(deg)
+printer.text(' ')
+printer.text('\n')
+printer.text('Sky: ' + cond)
+printer.text('\n')
+printer.text('\n')
+
+# Print forecast
+printer.set(font='a', height=2, align='center', bold=True, double_height=False)
+printer.text('Forecast: \n')
+forecast(0)
+forecast(1)
+printer.cut()
+printer.control("LF")

setup.py

@@ -68,7 +68,6 @@ setup(
     url='https://github.com/python-escpos/python-escpos',
     download_url='https://github.com/python-escpos/python-escpos/archive/master.zip',
     description='Python library to manipulate ESC/POS Printers',
-    bugtrack_url='https://github.com/python-escpos/python-escpos/issues',
     license='MIT',
     long_description=read('README.rst'),
     author='Manuel F Martinez and others',
@@ -114,7 +113,7 @@ setup(
         'pyserial',
         'six',
         'appdirs',
-        'pyyaml',
+        'PyYAML',
         'argparse',
         'argcomplete',
         'future',
@@ -126,7 +125,7 @@ setup(
     tests_require=[
         'jaconv',
         'tox',
-        'pytest',
+        'pytest!=3.2.0',
         'pytest-cov',
         'pytest-mock',
         'nose',

src/escpos/capabilities.py

@@ -1,16 +1,47 @@
 import re
-import six
 from os import environ, path
+import pickle
+import logging
+import time
+
+import six
 import yaml
 
-# Load external printer database
-if 'ESCPOS_CAPABILITIES_FILE' in environ:
-    file_path = environ['ESCPOS_CAPABILITIES_FILE']
-else:
-    file_path = path.join(path.dirname(__file__), 'capabilities.json')
 
-with open(file_path) as f:
-    CAPABILITIES = yaml.load(f)
+logging.basicConfig()
+logger = logging.getLogger(__name__)
+
+
+pickle_dir = environ.get('ESCPOS_CAPABILITIES_PICKLE_DIR', '/tmp/')
+pickle_path = path.join(pickle_dir, 'capabilities.pickle')
+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.load(cp)
+        pickle.dump(CAPABILITIES, pp, protocol=2)
+
+logger.debug('Finished loading capabilities took %.2fs', time.time() - t0)
+
 
 PROFILES = CAPABILITIES['profiles']
 

src/escpos/constants.py

@@ -225,6 +225,24 @@ BARCODE_TYPE_B = {
     'GS1 DATABAR EXPANDED':        _SET_BARCODE_TYPE(78),
 }
 
+BARCODE_FORMATS = {
+    'UPC-A':                       ([(11, 12)], "^[0-9]{11,12}$"),
+    'UPC-E':                       ([(7, 8), (11, 12)], "^([0-9]{7,8}|[0-9]{11,12})$"),
+    'EAN13':                       ([(12, 13)], "^[0-9]{12,13}$"),
+    'EAN8':                        ([(7, 8)], "^[0-9]{7,8}$"),
+    'CODE39':                      ([(1, 255)], "^([0-9A-Z \$\%\+\-\.\/]+|\*[0-9A-Z \$\%\+\-\.\/]+\*)$"),
+    'ITF':                         ([(2, 255)], "^([0-9]{2})+$"),
+    'NW7':                         ([(1, 255)], "^[A-Da-d][0-9\$\+\-\.\/\:]+[A-Da-d]$"),
+    'CODABAR':                     ([(1, 255)], "^[A-Da-d][0-9\$\+\-\.\/\:]+[A-Da-d]$"),  # Same as NW7
+    'CODE93':                      ([(1, 255)], "^[\\x00-\\x7F]+$"),
+    'CODE128':                     ([(2, 255)], "^\{[A-C][\\x00-\\x7F]+$"),
+    'GS1-128':                     ([(2, 255)], "^\{[A-C][\\x00-\\x7F]+$"), # same as CODE128
+    'GS1 DATABAR OMNIDIRECTIONAL': ([(13,13)], "^[0-9]{13}$"),
+    'GS1 DATABAR TRUNCATED':       ([(13,13)], "^[0-9]{13}$"), # same as GS1 omnidirectional
+    'GS1 DATABAR LIMITED':         ([(13,13)], "^[01][0-9]{12}$"),
+    'GS1 DATABAR EXPANDED':        ([(2,255)], "^\([0-9][A-Za-z0-9 \!\"\%\&\'\(\)\*\+\,\-\.\/\:\;\<\=\>\?\_\{]+$"),
+}
+
 BARCODE_TYPES = {
     'A': BARCODE_TYPE_A,
     'B': BARCODE_TYPE_B,
@@ -251,5 +269,10 @@ S_RASTER_2H = _PRINT_RASTER_IMG(b'\x02')  # Set raster image double height
 S_RASTER_Q  = _PRINT_RASTER_IMG(b'\x03')  # Set raster image quadruple
 
 # Status Command
-RT_STATUS_ONLINE = DLE + EOT +  b'\x01';
-RT_MASK_ONLINE = 8;
+RT_STATUS = DLE + EOT
+RT_STATUS_ONLINE = RT_STATUS +  b'\x01'
+RT_STATUS_PAPER = RT_STATUS +  b'\x04'
+RT_MASK_ONLINE = 8
+RT_MASK_PAPER = 18
+RT_MASK_LOWPAPER = 30
+RT_MASK_NOPAPER = 114

src/escpos/escpos.py

@@ -19,13 +19,14 @@ import qrcode
 import textwrap
 import six
 import time
+from re import match as re_match
 
 import barcode
 from barcode.writer import ImageWriter
 
 from .constants import ESC, GS, NUL, QR_ECLEVEL_L, QR_ECLEVEL_M, QR_ECLEVEL_H, QR_ECLEVEL_Q
 from .constants import QR_MODEL_1, QR_MODEL_2, QR_MICRO, BARCODE_TYPES, BARCODE_HEIGHT, BARCODE_WIDTH
-from .constants import BARCODE_FONT_A, BARCODE_FONT_B
+from .constants import BARCODE_FONT_A, BARCODE_FONT_B, BARCODE_FORMATS
 from .constants import BARCODE_TXT_OFF, BARCODE_TXT_BTH, BARCODE_TXT_ABV, BARCODE_TXT_BLW
 from .constants import TXT_SIZE, TXT_NORMAL
 from .constants import SET_FONT
@@ -36,6 +37,7 @@ from .constants import HW_RESET, HW_SELECT, HW_INIT
 from .constants import CTL_VT, CTL_CR, CTL_FF, CTL_LF, CTL_SET_HT, PANEL_BUTTON_OFF, PANEL_BUTTON_ON
 from .constants import TXT_STYLE
 from .constants import RT_STATUS_ONLINE, RT_MASK_ONLINE
+from .constants import RT_STATUS_PAPER, RT_MASK_PAPER, RT_MASK_LOWPAPER, RT_MASK_NOPAPER
 
 from .exceptions import BarcodeTypeError, BarcodeSizeError, TabPosError
 from .exceptions import CashDrawerError, SetVariableError, BarcodeCodeError
@@ -79,14 +81,14 @@ class Escpos(object):
         """
         pass
 
-    def _read(self, msg):
+    def _read(self):
         """ Returns a NotImplementedError if the instance of the class doesn't override this method.
         :raises NotImplementedError
         """
         raise NotImplementedError()
 
     def image(self, img_source, high_density_vertical=True, high_density_horizontal=True, impl="bitImageRaster",
-              fragment_height=960):
+              fragment_height=960, center=False):
         """ Print an image
 
         You can select whether the printer should print in high density or not. The default value is high density.
@@ -107,14 +109,19 @@ class Escpos(object):
         :param high_density_horizontal: print in high density in horizontal direction *default:* True
         :param impl: choose image printing mode between `bitImageRaster`, `graphics` or `bitImageColumn`
         :param fragment_height: Images larger than this will be split into multiple fragments *default:* 960
+        :param center: Center image horizontally *default:* False
 
         """
         im = EscposImage(img_source)
 
         try:
             max_width = int(self.profile.profile_data['media']['width']['pixels'])
+
             if im.width > max_width:
                 raise ImageWidthError('{} > {}'.format(im.width, max_width))
+
+            if center:
+                im.center(max_width)
         except KeyError:
             # If the printer's pixel width is not known, print anyways...
             pass
@@ -172,7 +179,8 @@ class Escpos(object):
         header = self._int_low_high(len(data) + 2, 2)
         self._raw(GS + b'(L' + header + m + fn + data)
 
-    def qr(self, content, ec=QR_ECLEVEL_L, size=3, model=QR_MODEL_2, native=False):
+    def qr(self, content, ec=QR_ECLEVEL_L, size=3, model=QR_MODEL_2,
+           native=False, center=False):
         """ Print QR Code for the provided string
 
         :param content: The content of the code. Numeric data will be more efficiently compacted.
@@ -184,6 +192,7 @@ class Escpos(object):
             by all printers).
         :param native: True to render the code on the printer, False to render the code as an image and send it to the
             printer (Default)
+        :param center: Centers the code *default:* False
         """
         # Basic validation
         if ec not in [QR_ECLEVEL_L, QR_ECLEVEL_M, QR_ECLEVEL_H, QR_ECLEVEL_Q]:
@@ -210,12 +219,17 @@ class Escpos(object):
             qr_code.make(fit=True)
             qr_img = qr_code.make_image()
             im = qr_img._img.convert("RGB")
+
             # Convert the RGB image in printable image
             self.text('\n')
-            self.image(im)
+            self.image(im, center=center)
             self.text('\n')
             self.text('\n')
             return
+
+        if center:
+            raise NotImplementedError("Centering not implemented for native QR rendering")
+
         # Native 2D code printing
         cn = b'1'  # Code type for QR code
         # Select model: 1, 2 or micro.
@@ -250,9 +264,9 @@ class Escpos(object):
         """
         max_input = (256 << (out_bytes * 8) - 1)
         if not 1 <= out_bytes <= 4:
-            raise ValueError("Can only output 1-4 byes")
+            raise ValueError("Can only output 1-4 bytes")
         if not 0 <= inp_number <= max_input:
-            raise ValueError("Number too large. Can only output up to {0} in {1} byes".format(max_input, out_bytes))
+            raise ValueError("Number too large. Can only output up to {0} in {1} bytes".format(max_input, out_bytes))
         outp = b''
         for _ in range(0, out_bytes):
             outp += six.int2byte(inp_number % 256)
@@ -274,17 +288,42 @@ class Escpos(object):
         else:
             self.magic.force_encoding(code)
 
+    @staticmethod
+    def check_barcode(bc, code):
+        """
+        This method checks if the barcode is in the proper format.
+        The validation concerns the barcode length and the set of characters, but won't compute/validate any checksum.
+        The full set of requirement for each barcode type is available in the ESC/POS documentation.
+
+        As an example, using EAN13, the barcode `12345678901` will be correct, because it can be rendered by the
+        printer. But it does not suit the EAN13 standard, because the checksum digit is missing. Adding a wrong
+        checksum in the end will also be considered correct, but adding a letter won't (EAN13 is numeric only).
+
+        .. todo:: Add a method to compute the checksum for the different standards
+
+        .. todo:: For fixed-length standards with mandatory checksum (EAN, UPC),
+            compute and add the checksum automatically if missing.
+
+        :param bc: barcode format, see :py:func`~escpos.Escpos.barcode`
+        :param code: alphanumeric data to be printed as bar code, see :py:func`~escpos.Escpos.barcode`
+        :return: bool
+        """
+        if bc not in BARCODE_FORMATS:
+            return False
+
+        bounds, regex = BARCODE_FORMATS[bc]
+        return any(bound[0] <= len(code) <= bound[1] for bound in bounds) and re_match(regex, code)
+
     def barcode(self, code, bc, height=64, width=3, pos="BELOW", font="A",
-                align_ct=True, function_type=None):
+                align_ct=True, function_type=None, check=True):
         """ Print Barcode
 
         This method allows to print barcodes. The rendering of the barcode is done by the printer and therefore has to
-        be supported by the unit. Currently you have to check manually whether your barcode text is correct. Uncorrect
-        barcodes may lead to unexpected printer behaviour. There are two forms of the barcode function. Type A is
-        default but has fewer barcodes, while type B has some more to choose from.
-
-        .. todo:: Add a method to check barcode codes. Alternatively or as an addition write explanations about each
-                  barcode-type. Research whether the check digits can be computed autmatically.
+        be supported by the unit. By default, this method will check whether your barcode text is correct, that is
+        the characters and lengths are supported by ESCPOS. Call the method with `check=False` to disable the check, but
+        note that uncorrect barcodes may lead to unexpected printer behaviour.
+        There are two forms of the barcode function. Type A is default but has fewer barcodes,
+        while type B has some more to choose from.
 
         Use the parameters `height` and `width` for adjusting of the barcode size. Please take notice that the barcode
         will not be printed if it is outside of the printable area. (Which should be impossible with this method, so
@@ -352,6 +391,10 @@ class Escpos(object):
             function based on the current profile.
             *default*: A
 
+        :param check: If this parameter is True, the barcode format will be checked to ensure it meets the bc
+            requirements as defigned in the esc/pos documentation. See py:func:`~escpos.Escpos.check_barcode`
+            for more information. *default*: True.
+
         :raises: :py:exc:`~escpos.exceptions.BarcodeSizeError`,
                  :py:exc:`~escpos.exceptions.BarcodeTypeError`,
                  :py:exc:`~escpos.exceptions.BarcodeCodeError`
@@ -374,12 +417,19 @@ class Escpos(object):
         bc_types = BARCODE_TYPES[function_type.upper()]
         if bc.upper() not in bc_types.keys():
             raise BarcodeTypeError((
-                "Barcode type '{bc}' not valid for barcode function type "
+                "Barcode '{bc}' not valid for barcode function type "
                 "{function_type}").format(
                     bc=bc,
                     function_type=function_type,
                 ))
 
+        if check and not self.check_barcode(bc, code):
+            raise BarcodeCodeError((
+                "Barcode '{code}' not in a valid format for type '{bc}'").format(
+                code=code,
+                bc=bc,
+            ))
+
         # Align Bar Code()
         if align_ct:
             self._raw(TXT_STYLE['align']['center'])
@@ -459,6 +509,28 @@ class Escpos(object):
         txt = six.text_type(txt)
         self.magic.write(txt)
 
+    def textln(self, txt=''):
+        """Print alpha-numeric text with a newline
+
+        The text has to be encoded in the currently selected codepage.
+        The input text has to be encoded in unicode.
+
+        :param txt: text to be printed with a newline
+        :raises: :py:exc:`~escpos.exceptions.TextError`
+        """
+        self.text('{}\n'.format(txt))
+
+    def ln(self, count=1):
+        """Print a newline or more
+
+        :param count: number of newlines to print
+        :raises: :py:exc:`ValueError` if count < 0
+        """
+        if count < 0:
+            raise ValueError('Count cannot be lesser than 0')
+        if count > 0:
+            self.text('\n' * count)
+
     def block_text(self, txt, font=None, columns=None):
         """ Text is printed wrapped to specified columns
 
@@ -754,19 +826,40 @@ class Escpos(object):
         else:
             self._raw(PANEL_BUTTON_OFF)
 
-    def query_status(self):
+    def query_status(self, mode):
         """ Queries the printer for its status, and returns an array of integers containing it.
+        :param mode: Integer that sets the status mode queried to the printer.
+        RT_STATUS_ONLINE: Printer status.
+        RT_STATUS_PAPER: Paper sensor.
         :rtype: array(integer)"""
-        self._raw(RT_STATUS_ONLINE)
+        self._raw(mode)
         time.sleep(1)
         status = self._read()
-        return status or [RT_MASK_ONLINE]
+        return status
 
     def is_online(self):
         """ Queries the printer its online status.
         When online, returns True; False otherwise.
         :rtype: bool: True if online, False if offline."""
-        return not (self.query_status()[0] & RT_MASK_ONLINE)
+        status = self.query_status(RT_STATUS_ONLINE)
+        if len(status) == 0:
+            return False
+        return not (status & RT_MASK_ONLINE)
+
+    def paper_status(self):
+        """ Queries the printer its paper status.
+        Returns 2 if there is plenty of paper, 1 if the paper has arrived to
+        the near-end sensor and 0 if there is no paper.
+        :rtype: int: 2: Paper is adequate. 1: Paper ending. 0: No paper."""
+        status = self.query_status(RT_STATUS_PAPER)
+        if len(status) == 0:
+            return 2
+        if (status[0] & RT_MASK_NOPAPER == RT_MASK_NOPAPER):
+            return 0
+        if (status[0] & RT_MASK_LOWPAPER == RT_MASK_LOWPAPER):
+            return 1
+        if (status[0] & RT_MASK_PAPER == RT_MASK_PAPER):
+            return 2
 
 
 class EscposIO(object):

src/escpos/exceptions.py

@@ -77,9 +77,10 @@ class BarcodeSizeError(Error):
 
 
 class BarcodeCodeError(Error):
-    """ No Barcode code was supplied.
+    """ No Barcode code was supplied, or it is incorrect.
 
-    No data for the barcode has been supplied in :py:meth:`escpos.escpos.Escpos.barcode`.
+    No data for the barcode has been supplied in :py:meth:`escpos.escpos.Escpos.barcode` or the the `check` parameter
+    was True and the check failed.
     The returncode for this exception is `30`.
     """
     def __init__(self, msg=""):

src/escpos/image.py

@@ -115,3 +115,19 @@ class EscposImage(object):
             box = (left, upper, right, lower)
             fragments.append(self.img_original.crop(box))
         return fragments
+
+    def center(self, max_width):
+        """In-place image centering
+
+        :param: Maximum width in order to deduce x offset for centering
+        :return: None
+        """
+        old_width, height = self._im.size
+        new_size = (max_width, height)
+
+        new_im = Image.new("1", new_size)
+        paste_x = int((max_width - old_width) / 2)
+
+        new_im.paste(self._im, (paste_x, 0))
+
+        self._im = new_im

src/escpos/printer.py

@@ -155,6 +155,10 @@ class Serial(Escpos):
         """
         self.device.write(msg)
 
+    def _read(self):
+        """ Reads a data buffer and returns it to the caller. """
+        return self.device.read(16)
+
     def close(self):
         """ Close Serial interface """
         if self.device is not None and self.device.is_open:
@@ -239,7 +243,7 @@ class File(Escpos):
     def __init__(self, devfile="/dev/usb/lp0", auto_flush=True, *args, **kwargs):
         """
 
-        :param devfile : Device file under dev filesystem
+        :param devfile: Device file under dev filesystem
         :param auto_flush: automatically call flush after every call of _raw()
         """
         Escpos.__init__(self, *args, **kwargs)

test/test_function_barcode.py

@@ -7,7 +7,7 @@ from __future__ import unicode_literals
 import escpos.printer as printer
 from escpos.constants import BARCODE_TYPE_A, BARCODE_TYPE_B
 from escpos.capabilities import Profile, BARCODE_B
-from escpos.exceptions import BarcodeTypeError
+from escpos.exceptions import BarcodeTypeError, BarcodeCodeError
 import pytest
 
 
@@ -36,3 +36,17 @@ def test_lacks_support(bctype, supports_b):
         instance.barcode('test', bctype)
 
     assert instance.output == b''
+
+
+@pytest.mark.parametrize("bctype,data", [
+    ('EAN13', 'AA'),
+    ('CODE128', '{D2354AA'),
+])
+def test_code_check(bctype, data):
+    """should raise an error if the barcode code is invalid.
+    """
+    instance = printer.Dummy()
+    with pytest.raises(BarcodeCodeError):
+        instance.barcode(data, bctype)
+
+    assert instance.output == b''

test/test_function_check_barcode.py

@@ -0,0 +1,104 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+from __future__ import unicode_literals
+
+import escpos.printer as printer
+import pytest
+
+
+@pytest.mark.parametrize("bctype,data", [
+    ('UPC-A', '01234567890'),
+    ('UPC-A', '012345678905'),
+    ('UPC-E', '01234567'),
+    ('UPC-E', '0123456'),
+    ('UPC-E', '012345678905'),
+    ('EAN13', '0123456789012'),
+    ('EAN13', '012345678901'),
+    ('EAN8', '01234567'),
+    ('EAN8', '0123456'),
+    ('CODE39', 'ABC-1234'),
+    ('CODE39', 'ABC-1234-$$-+A'),
+    ('CODE39', '*WIKIPEDIA*'),
+    ('ITF', '010203040506070809'),
+    ('ITF', '11221133113344556677889900'),
+    ('CODABAR', 'A2030405060B'),
+    ('CODABAR', 'C11221133113344556677889900D'),
+    ('CODABAR', 'D0D'),
+    ('NW7', 'A2030405060B'),
+    ('NW7', 'C11221133113344556677889900D'),
+    ('NW7', 'D0D'),
+    ('CODE93', 'A2030405060B'),
+    ('CODE93', '+:$&23-7@$'),
+    ('CODE93', 'D0D'),
+    ('CODE128', '{A2030405060B'),
+    ('CODE128', '{C+:$&23-7@$'),
+    ('CODE128', '{B0D'),
+    ('GS1-128', '{A2030405060B'),
+    ('GS1-128', '{C+:$&23-7@$'),
+    ('GS1-128', '{B0D'),
+    ('GS1 DATABAR OMNIDIRECTIONAL', '0123456789123'),
+    ('GS1 DATABAR TRUNCATED', '0123456789123'),
+    ('GS1 DATABAR LIMITED', '0123456789123'),
+    ('GS1 DATABAR EXPANDED', '(9A{A20304+-%&06a0B'),
+    ('GS1 DATABAR EXPANDED', '(1 {C+:&23-7%'),
+    ('GS1 DATABAR EXPANDED', '(00000001234567678'),
+])
+def test_check_valid_barcode(bctype, data):
+    assert (printer.Escpos.check_barcode(bctype, data))
+
+
+@pytest.mark.parametrize("bctype,data", [
+    ('UPC-A', '01234567890123'),  # too long
+    ('UPC-A', '0123456789'),  # too short
+    ('UPC-A', '72527273-711'),  # invalid '-'
+    ('UPC-A', 'A12345678901'),  # invalid 'A'
+    ('UPC-E', '01234567890123'),  # too long
+    ('UPC-E', '012345'),  # too short
+    ('UPC-E', '72527-2'),  # invalid '-'
+    ('UPC-E', 'A123456'),  # invalid 'A'
+    ('EAN13', '0123456789'),  # too short
+    ('EAN13', 'A123456789012'),  # invalid 'A'
+    ('EAN13', '012345678901234'),  # too long
+    ('EAN8', '012345'),  # too short
+    ('EAN8', 'A123456789012'),  # invalid 'A'
+    ('EAN8', '012345678901234'),  # too long
+    ('CODE39', 'ALKJ_34'),  # invalid '_'
+    ('CODE39', 'A' * 256),  # too long
+    ('ITF', '010203040'),  # odd length
+    ('ITF', '0' * 256),  # too long
+    ('ITF', 'AB01'),  # invalid 'A'
+    ('CODABAR', '010203040'),  # no start/stop
+    ('CODABAR', '0' * 256),  # too long
+    ('CODABAR', 'AB-01F'),  # invalid 'B'
+    ('NW7', '010203040'),  # no start/stop
+    ('NW7', '0' * 256),  # too long
+    ('NW7', 'AB-01F'),  # invalid 'B'
+    ('CODE93', 'é010203040'),  # invalid 'é'
+    ('CODE93', '0' * 256),  # too long
+    ('CODE128', '010203040'),  # missing leading {
+    ('CODE128', '{D2354AA'),  # second char not between A-C
+    ('CODE128', '0' * 256),  # too long
+    ('GS1-128', '010203040'),  # missing leading {
+    ('GS1-128', '{D2354AA'),  # second char not between A-C
+    ('GS1-128', '0' * 256),  # too long
+    ('GS1 DATABAR OMNIDIRECTIONAL', '01234567891234'),  # too long
+    ('GS1 DATABAR OMNIDIRECTIONAL', '012345678912'),  # too short
+    ('GS1 DATABAR OMNIDIRECTIONAL', '012345678A1234'),  # invalid 'A'
+    ('GS1 DATABAR TRUNCATED', '01234567891234'),  # too long
+    ('GS1 DATABAR TRUNCATED', '012345678912'),  # too short
+    ('GS1 DATABAR TRUNCATED', '012345678A1234'),  # invalid 'A'
+    ('GS1 DATABAR LIMITED', '01234567891234'),  # too long
+    ('GS1 DATABAR LIMITED', '012345678912'),  # too short
+    ('GS1 DATABAR LIMITED', '012345678A1234'),  # invalid 'A'
+    ('GS1 DATABAR LIMITED', '02345678912341'),  # invalid start (should be 01)
+    ('GS1 DATABAR EXPANDED', '010203040'),  # missing leading (
+    ('GS1-128', '(' + ('0' * 256)),  # too long
+    ('GS1 DATABAR EXPANDED', '(a{D2354AA'),  # second char not between 0-9
+    ('GS1 DATABAR EXPANDED', 'IT will fail'),  # first char not '('
+])
+def test_check_invalid_barcode(bctype, data):
+    assert (not printer.Escpos.check_barcode(bctype, data))

test/test_function_image.py

@@ -145,10 +145,8 @@ def test_large_graphics():
     assert(instance.output == b'\x1dv0\x00\x01\x00\x01\x00\xc0\x1dv0\x00\x01\x00\x01\x00\x00')
 
 
-def test_width_too_large():
-    """
-    Test printing an image that is too large in width.
-    """
+@pytest.fixture
+def dummy_with_width():
     instance = printer.Dummy()
     instance.profile.profile_data = {
         'media': {
@@ -157,8 +155,25 @@ def test_width_too_large():
             }
         }
     }
+    return instance
+
+
+def test_width_too_large(dummy_with_width):
+    """
+    Test printing an image that is too large in width.
+    """
+    instance = dummy_with_width
 
     with pytest.raises(ImageWidthError):
         instance.image(Image.new("RGB", (385, 200)))
 
     instance.image(Image.new("RGB", (384, 200)))
+
+
+def test_center_image(dummy_with_width):
+    instance = dummy_with_width
+
+    with pytest.raises(ImageWidthError):
+        instance.image(Image.new("RGB", (385, 200)), center=True)
+
+    instance.image(Image.new("RGB", (384, 200)), center=True)

test/test_function_qr_native.py

@@ -13,6 +13,8 @@ from __future__ import print_function
 from __future__ import unicode_literals
 
 from nose.tools import raises
+import pytest
+
 import escpos.printer as printer
 from escpos.constants import QR_ECLEVEL_H, QR_MODEL_1
 
@@ -25,7 +27,6 @@ def test_defaults():
         b'(k\x07\x001P01234\x1d(k\x03\x001Q0'
     assert(instance.output == expected)
 
-
 def test_empty():
     """Test QR printing blank code"""
     instance = printer.Dummy()
@@ -99,3 +100,13 @@ def test_image_invalid_model():
     """Test unsupported QR model as image"""
     instance = printer.Dummy()
     instance.qr("1234", native=False, model=QR_MODEL_1)
+
+
+@pytest.fixture
+def instance():
+    return printer.Dummy()
+
+
+def test_center_not_implementer(instance):
+    with pytest.raises(NotImplementedError):
+        instance.qr("test", center=True, native=True)

test/test_function_qr_non-native.py

@@ -13,6 +13,7 @@ from __future__ import division
 from __future__ import print_function
 from __future__ import unicode_literals
 
+import pytest
 import mock
 
 from escpos.printer import Dummy
@@ -30,3 +31,12 @@ def test_type_of_object_passed_to_image_function(img_function):
     d.qr("LoremIpsum")
     args, kwargs = img_function.call_args
     assert isinstance(args[0], Image.Image)
+
+
+@pytest.fixture
+def instance():
+    return Dummy()
+
+
+def test_center(instance):
+    instance.qr("LoremIpsum", center=True)

test/test_function_text.py

@@ -39,3 +39,27 @@ def test_block_text():
         "All the presidents men were eating falafel for breakfast.", font='a')
     assert printer.output == \
         b'All the presidents men were eating falafel\nfor breakfast.'
+
+
+def test_textln():
+    printer = get_printer()
+    printer.textln('hello, world')
+    assert printer.output == b'hello, world\n'
+
+
+def test_textln_empty():
+    printer = get_printer()
+    printer.textln()
+    assert printer.output == b'\n'
+
+
+def test_ln():
+    printer = get_printer()
+    printer.ln()
+    assert printer.output == b'\n'
+
+
+def test_multiple_ln():
+    printer = get_printer()
+    printer.ln(3)
+    assert printer.output == b'\n\n\n'

test/test_printer_file.py

@@ -16,7 +16,7 @@ from __future__ import unicode_literals
 import six
 
 import pytest
-from hypothesis import given
+from hypothesis import given, settings
 from hypothesis.strategies import text
 
 import escpos.printer as printer
@@ -27,6 +27,7 @@ else:
     mock_open_call = '__builtin__.open'
 
 
+@settings(use_coverage=False)
 @given(path=text())
 def test_load_file_printer(mocker, path):
     """test the loading of the file-printer"""
@@ -37,6 +38,7 @@ def test_load_file_printer(mocker, path):
     mock_open.assert_called_with(path, "wb")
 
 
+@settings(deadline=None, use_coverage=False)
 @given(txt=text())
 def test_auto_flush(mocker, txt):
     """test auto_flush in file-printer"""
@@ -57,6 +59,7 @@ def test_auto_flush(mocker, txt):
     assert mock_device.flush.called
 
 
+@settings(deadline=None, use_coverage=False)
 @given(txt=text())
 def test_flush_on_close(mocker, txt):
     """test flush on close in file-printer"""

test/test_raise_arbitrary_error.py

@@ -0,0 +1,32 @@
+#!/usr/bin/python
+"""test the raising of errors with the error module
+
+:author: `Patrick Kanzler <patrick.kanzler@fablab.fau.de>`_
+:organization: `python-escpos <https://github.com/python-escpos>`_
+:copyright: Copyright (c) 2017 `python-escpos <https://github.com/python-escpos>`_
+:license: MIT
+"""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+from __future__ import unicode_literals
+
+import pytest
+import escpos
+import escpos.exceptions
+
+
+def test_raise_error_wrongly():
+    """raise error the wrong way
+
+    should reproduce https://github.com/python-escpos/python-escpos/issues/257
+    """
+    with pytest.raises(AttributeError):
+        raise escpos.Error("This should raise an AttributeError.")
+
+
+def tests_raise_error():
+    """raise error the right way"""
+    with pytest.raises(escpos.exceptions.Error):
+        raise escpos.exceptions.Error("This should raise an error.")

tox.ini

@@ -7,10 +7,11 @@ deps = nose
        coverage
        scripttest
        mock
-       pytest
+       pytest!=3.2.0
        pytest-cov
        pytest-mock
        hypothesis
+       viivakoodi
 commands = py.test --cov escpos
 
 [testenv:docs]
@@ -18,6 +19,7 @@ basepython = python
 changedir = doc
 deps = sphinx>=1.5.1
        setuptools_scm
+       viivakoodi
 commands = sphinx-build -W -b html -d {envtmpdir}/doctrees .  {envtmpdir}/html
 
 [testenv:flake8]