def load_engine():
"""Returns an instance of the user's choice of barcode reading engine
"""
try:
from gouda.engines import InliteEngine, LibDMTXEngine, ZbarEngine
except ImportError:
raise InselectError('Barcode decoding is not available')
else:
settings = current_settings()
engine = settings['engine']
if 'libdmtx' == engine:
return LibDMTXEngine()
elif 'zbar' == engine:
return ZbarEngine()
elif 'inlite' == engine:
return InliteEngine(settings['inlite-format'])
else:
raise ValueError(
'Unrecognised barcode reader [{0}]'.format(engine))
