Automatically choose correct barcode function.

Tests for barcode function.

src/escpos/capabilities.py

@@ -15,6 +15,9 @@ class NotSupported(Exception):
     pass
 
 
+BARCODE_B = 'barcodeB'
+
+
 class BaseProfile(object):
     """This respresents a printer profile.
 
@@ -43,6 +46,11 @@ class BaseProfile(object):
         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_profile(name=None, **kwargs):
     """Get the profile by name; if no name is given, return the
@@ -84,10 +92,11 @@ def clean(s):
 # For users, who want to provide their profile
 class Profile(get_profile_class('default')):
 
-    def __init__(self, columns=None):
-        super(Profile, self).__init()
+    def __init__(self, columns=None, features={}):
+        super(Profile, self).__init__()
 
         self.columns = columns
+        self.features = features
 
     def get_columns(self, font):
         if self.columns is not None:

src/escpos/escpos.py

@@ -23,7 +23,7 @@ from .exceptions import *
 
 from abc import ABCMeta, abstractmethod  # abstract base class support
 from escpos.image import EscposImage
-from escpos.capabilities import get_profile
+from escpos.capabilities import get_profile, BARCODE_B
 
 
 @six.add_metaclass(ABCMeta)
@@ -293,7 +293,8 @@ class Escpos(object):
         else:
             raise CharCodeError()
 
-    def barcode(self, code, bc, height=64, width=3, pos="BELOW", font="A", align_ct=True, function_type="A"):
+    def barcode(self, code, bc, height=64, width=3, pos="BELOW", font="A",
+                align_ct=True, function_type=None):
         """ Print Barcode
 
         This method allows to print barcodes. The rendering of the barcode is done by the printer and therefore has to
@@ -364,14 +365,40 @@ class Escpos(object):
                          issued.
         :type align_ct: bool
 
-        :param function_type: Choose between ESCPOS function type A or B, depending on printer support and desired
-            barcode.
+        :param function_type: Choose between ESCPOS function type A or B,
+            depending on printer support and desired barcode. If not given,
+            the printer will attempt to automatically choose the correct
+            function based on the current profile.
             *default*: A
 
         :raises: :py:exc:`~escpos.exceptions.BarcodeSizeError`,
                  :py:exc:`~escpos.exceptions.BarcodeTypeError`,
                  :py:exc:`~escpos.exceptions.BarcodeCodeError`
         """
+        if function_type is None:
+            # Choose the function type automatically.
+            if bc in BARCODE_TYPES['A']:
+                function_type = 'A'
+            else:
+                if bc in BARCODE_TYPES['B']:
+                    if not self.profile.supports(BARCODE_B):
+                        raise BarcodeTypeError((
+                            "Barcode type '{bc} not supported for "
+                            "the current printer profile").format(bc=bc))
+                    function_type = 'B'
+                else:
+                    raise BarcodeTypeError((
+                            "Barcode type '{bc} is not valid").format(bc=bc))
+
+        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 "
+                "{function_type}").format(
+                    bc=bc,
+                    function_type=function_type,
+                ))
+
         # Align Bar Code()
         if align_ct:
             self._raw(TXT_ALIGN_CT)
@@ -400,14 +427,6 @@ class Escpos(object):
         else:  # DEFAULT POSITION: BELOW
             self._raw(BARCODE_TXT_BLW)
 
-        bc_types = BARCODE_TYPES[function_type.upper()]
-        if bc.upper() not in bc_types.keys():
-            # TODO: Raise a better error, or fix the message of this error type
-            raise BarcodeTypeError("Barcode type {bc} not valid for barcode function type {function_type}".format(
-                bc=bc,
-                function_type=function_type,
-            ))
-
         self._raw(bc_types[bc.upper()])
 
         if function_type.upper() == "B":

test/test_function_barcode.py

@@ -0,0 +1,34 @@
+#!/usr/bin/python
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+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
+import pytest
+
+
+@pytest.mark.parametrize("bctype,data,expected", [
+    ('EAN13', '4006381333931',
+        b'\x1ba\x01\x1dh@\x1dw\x03\x1df\x00\x1dH\x02\x1dk\x024006381333931\x00')
+])
+def test_barcode(bctype, data, expected):
+    instance = printer.Dummy()
+    instance.barcode(data, bctype)
+    assert instance.output == expected
+
+
+@pytest.mark.parametrize("bctype,supports_b", [
+    ('invalid', True),
+    ('CODE128', False),
+])
+def test_lacks_support(bctype, supports_b):
+    profile = Profile(features={BARCODE_B: supports_b})
+    instance = printer.Dummy(profile=profile)
+    with pytest.raises(BarcodeTypeError):
+        instance.barcode('test', bctype)
+
+    assert instance.output == ''