Merge pull request #3009 from initOS/8.0-fix_escpos_with_non_rgba_image

Bug: Exception when printing POS receipt via hardware proxy

diff --combined addons/hw_escpos/escpos/escpos.py
index 7a08486,bb60d63..ee6e20b
--- 1/addons/hw_escpos/escpos/escpos.py
--- 2/addons/hw_escpos/escpos/escpos.py
+++ b/addons/hw_escpos/escpos/escpos.py
@@@ -6,8 -6,11 +6,8 @@@
  @license: GPL
  '''
  
 -try: 
 -    import qrcode
 -except ImportError:
 -    qrcode = None
  
 +import logging
  import time
  import copy
  import io
@@@ -21,19 -24,12 +21,19 @@@ import xml.dom.minidom as minido
  
  from PIL import Image
  
 +_logger = logging.getLogger(__name__)
 +
  try:
      import jcconv
  except ImportError:
      jcconv = None
 -    print 'ESC/POS: please install jcconv for improved Japanese receipt printing:'
 -    print ' # pip install jcconv'
 +    _logger.warning('ESC/POS: please install jcconv for improved Japanese receipt printing:\n  # pip install jcconv')
 +
 +try: 
 +    import qrcode
 +except ImportError:
 +    qrcode = None
 +    _logger.warning('ESC/POS: please install the qrcode python module for qrcode printing in point of sale receipts:\n  # pip install qrcode')
  
  from constants import *
  from exceptions import *
@@@ -442,7 -438,12 +442,12 @@@ class Escpos
              f.seek(0)
              img_rgba = Image.open(f)
              img = Image.new('RGB', img_rgba.size, (255,255,255))
-             img.paste(img_rgba, mask=img_rgba.split()[3]) 
+             channels = img_rgba.split()
+             if len(channels) > 1:
+                 # use alpha channel as mask
+                 img.paste(img_rgba, mask=channels[3])
+             else:
+                 img.paste(img_rgba)
  
              print 'convert image'