Reworking brother_ql/reader.py
The code used in BrotherQLReader.analyse() is now is now split into a chunker() function which separates (=chunks) a data stream of bytes into individual printer instructions and into the main functionality of the analyse() method: Stating debug information about each instruction and generating images of the expected printer output.
This commit is contained in:
Philipp Klaus
+56
-37
@@ -12,21 +12,21 @@ from matplotlib import pyplot as plt
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logger = logging.getLogger(__name__)
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cmds = {
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# signature name following bytes description
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b'\x00': ("preamble", 0, "Preamble, 200-300x 0x00 to clear comamnd buffer"),
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b'\x4D': ("compression", 1, ""),
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b'\x67': ("raster", -1, ""),
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b'\x0C': ("print", 0, "print intermediate page"),
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b'\x1A': ("print", 0, "print final page"),
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b'\x1b\x40': ("init", 0, "initialization"),
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b'\x1b\x69\x61': ("mode setting", 1, ""),
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b'\x1b\x69\x7A': ("media/quality", 10, "print-media and print-quality"),
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b'\x1b\x69\x4D': ("various", 1, "Auto cut flag in bit 7"),
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b'\x1b\x69\x41': ("cut-every", 1, "cut every n-th page"),
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b'\x1b\x69\x4B': ("expanded", 1, ""),
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b'\x1b\x69\x64': ("margins", 2, ""),
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b'\x1b\x69\x55\x77\x01': ('amedia',127, "Additional media information command"),
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b'\x1b\x69\x55\x4A': ('jobid', 14, "Job ID setting command"),
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# signature name following bytes description
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b'\x00': ("preamble", -1, "Preamble, 200-300x 0x00 to clear comamnd buffer"),
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b'\x4D': ("compression", 1, ""),
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b'\x67': ("raster", -1, ""),
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b'\x0C': ("print", 0, "print intermediate page"),
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b'\x1A': ("print", 0, "print final page"),
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b'\x1b\x40': ("init", 0, "initialization"),
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b'\x1b\x69\x61': ("mode setting", 1, ""),
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b'\x1b\x69\x7A': ("media/quality", 10, "print-media and print-quality"),
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b'\x1b\x69\x4D': ("various", 1, "Auto cut flag in bit 7"),
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b'\x1b\x69\x41': ("cut-every", 1, "cut every n-th page"),
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b'\x1b\x69\x4B': ("expanded", 1, ""),
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b'\x1b\x69\x64': ("margins", 2, ""),
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b'\x1b\x69\x55\x77\x01': ('amedia', 127, "Additional media information command"),
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b'\x1b\x69\x55\x4A': ('jobid', 14, "Job ID setting command"),
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}
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dot_widths = {
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@@ -39,6 +39,41 @@ def hex_format(data):
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except ValueError: # Py2
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return ' '.join('{:02X}'.format(ord(byte)) for byte in data)
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def chunker(data, raise_exception=False):
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"""
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Breaks data stream (bytes) into a list of bytes containing single instructions each.
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Logs warnings for unknown commands.
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If raise_exception is set to True it raise exceptions instead.
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returns: list of bytes
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"""
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instructions = []
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while True:
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if len(data) == 0: break
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cmd_found = False
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for command in cmds.keys():
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if data.startswith(command):
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cmd = cmds[command]
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num_bytes = len(command)
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if cmd[1] > 0: num_bytes += cmd[1]
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if cmd[0] == 'raster':
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num_bytes += data[2] + 2
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#payload = data[len(command):num_bytes]
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instructions.append(data[:num_bytes])
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data = data[num_bytes:]
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cmd_found = True
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if cmd_found:
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continue
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else:
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msg = 'unknown instruction starting with {}...)'.format(hex_format(data[0:4]))
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if raise_exception:
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raise ValueError(msg)
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else:
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logger.warning(msg)
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data = data[1:]
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return instructions
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class BrotherQLReader(object):
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def __init__(self, brother_file):
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@@ -52,23 +87,16 @@ class BrotherQLReader(object):
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self.page = 1
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def analyse(self):
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rem_script = self.brother_file.read()
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while True:
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if len(rem_script) == 0: break
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cmd_found = False
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instructions = self.brother_file.read()
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for instruction in chunker(instructions):
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for command in cmds.keys():
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if rem_script.startswith(command):
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if instruction.startswith(command):
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cmd = cmds[command]
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num_bytes = len(command)
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if cmd[1] > 0: num_bytes += cmd[1]
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if cmd[0] == 'init':
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self.mwidth, self.mheight = None, None
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self.raster_no = None
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self.rows = []
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if cmd[0] == 'raster':
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num_bytes += rem_script[2] + 2
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payload = rem_script[len(command):num_bytes]
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# now num_bytes and payload are accessable
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payload = instruction[len(command):]
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logger.info(" {} ({}) --> found! (payload: {})".format(cmd[0], hex_format(command), hex_format(payload)))
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if cmd[0] == 'compression':
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self.compression = payload[0] == 0x02
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@@ -95,8 +123,8 @@ class BrotherQLReader(object):
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self.rows.append(row)
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if cmd[0] == 'media/quality':
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self.raster_no = struct.unpack('<L', payload[4:8])[0]
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self.mwidth = rem_script[len(command) + 2]
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self.mlength = rem_script[len(command) + 3]*256
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self.mwidth = instruction[len(command) + 2]
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self.mlength = instruction[len(command) + 3]*256
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fmt = " media width: {}mm, media length: {}mm, raster no: {}dots"
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logger.info(fmt.format(self.mwidth, self.mlength, self.raster_no))
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if cmd[0] == 'print':
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@@ -111,12 +139,3 @@ class BrotherQLReader(object):
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im.save(img_name)
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print('Page saved as {}'.format(img_name))
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self.page += 1
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rem_script = rem_script[num_bytes:]
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cmd_found = True
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if cmd_found:
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continue
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else:
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logger.error('cmd not found: {0}... ({1}...)'.format(hex_format(rem_script[0:4]), rem_script[0:4]))
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rem_script = rem_script[1:]
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