Add LP Connector - UNIX printing via lp command

src/escpos/printer.py

@@ -9,14 +9,35 @@
 """
 
 
-import serial
+import os
 import socket
+import subprocess
+import sys
+
+import serial
 import usb.core
 import usb.util
 
 from .escpos import Escpos
 from .exceptions import USBNotFoundError
 
+_WIN32PRINT = False
+try:
+    import win32print
+
+    _WIN32PRINT = True
+except ImportError:
+    pass
+
+_CUPSPRINT = False
+try:
+    import cups
+    import tempfile
+
+    _CUPSPRINT = True
+except ImportError:
+    pass
+
 
 class Usb(Escpos):
     """USB printer
@@ -371,14 +392,6 @@ class Dummy(Escpos):
         pass
 
 
-_WIN32PRINT = False
-try:
-    import win32print
-
-    _WIN32PRINT = True
-except ImportError:
-    pass
-
 if _WIN32PRINT:
 
     class Win32Raw(Escpos):
@@ -421,18 +434,11 @@ if _WIN32PRINT:
             win32print.WritePrinter(self.hPrinter, msg)
 
 
-_CUPSPRINT = False
-try:
-    import cups
-    import tempfile
-    _CUPSPRINT = True
-except ImportError:
-    pass
-
 if _CUPSPRINT:
+
     class CupsPrinter(Escpos):
-        """ Simple CUPS printer connector.
-        """
+        """Simple CUPS printer connector."""
+
         def __init__(self, printer_name=None, *args, **kwargs):
             """CupsPrinter constructor.
 
@@ -445,26 +451,25 @@ if _CUPSPRINT:
             """
             Escpos.__init__(self, *args, **kwargs)
             host, port = args or (
-                kwargs.get('host', cups.getServer()),
-                kwargs.get('port', cups.getPort())
+                kwargs.get("host", cups.getServer()),
+                kwargs.get("port", cups.getPort()),
             )
             cups.setServer(host)
             cups.setPort(port)
             self.conn = cups.Connection()
             self.tmpfile = None
             self.printer_name = printer_name
-            self.job_name = ''
+            self.job_name = ""
             self.pending_job = False
             self.open()
 
         @property
         def printers(self):
-            """ Available CUPS printers.
-            """
+            """Available CUPS printers."""
             return self.conn.getPrinters()
 
-        def open(self, job_name='python-escpos'):
-            """ Setup a new print job and target printer.
+        def open(self, job_name="python-escpos"):
+            """Setup a new print job and target printer.
 
             A call to this method is required to send new jobs to
             the same CUPS connection.
@@ -478,7 +483,7 @@ if _CUPSPRINT:
             self.tmpfile = tempfile.NamedTemporaryFile(delete=True)
 
         def _raw(self, msg):
-            """ Append any command sent in raw format to temporary file
+            """Append any command sent in raw format to temporary file
 
             :param msg: arbitrary code to be printed
             :type msg: bytes
@@ -491,8 +496,7 @@ if _CUPSPRINT:
                 raise ValueError("Printer job not opened")
 
         def send(self):
-            """ Send the print job to the printer.
-            """
+            """Send the print job to the printer."""
             if self.pending_job:
                 # Rewind tempfile
                 self.tmpfile.seek(0)
@@ -501,11 +505,12 @@ if _CUPSPRINT:
                     self.printer_name,
                     self.tmpfile.name,
                     self.job_name,
-                    {"document-format": cups.CUPS_FORMAT_RAW})
+                    {"document-format": cups.CUPS_FORMAT_RAW},
+                )
             self._clear()
 
         def _clear(self):
-            """ Finish the print job.
+            """Finish the print job.
 
             Remove temporary file.
             """
@@ -513,13 +518,53 @@ if _CUPSPRINT:
             self.pending_job = False
 
         def close(self):
-            """ Close CUPS connection.
+            """Close CUPS connection.
 
             Send pending job to the printer if needed.
             """
             if self.pending_job:
                 self.send()
             if self.conn:
-                print('Closing CUPS connection to printer {}'.format(
-                    self.printer_name))
+                print("Closing CUPS connection to printer {}".format(self.printer_name))
                 self.conn = None
+
+
+if not sys.platform.startswith("win"):
+
+    class LP(Escpos):
+        """Simple UNIX lp raw printing.
+
+        From https://github.com/python-escpos/python-escpos/pull/348#issuecomment-549558316
+        """
+
+        def __init__(self, printer_name: str, *args, **kwargs):
+            Escpos.__init__(self, *args, **kwargs)
+            self.printer_name = printer_name
+            self.auto_flush = kwargs.get("auto_flush", True)
+            self.open()
+
+        def open(self):
+            self.lp = subprocess.Popen(
+                ["lp", "-d", self.printer_name, "-o", "raw"],
+                stdin=subprocess.PIPE,
+                stdout=open(os.devnull, "w"),
+            )
+
+        def close(self):
+            self.lp.terminate()
+
+        def flush(self):
+            if self.lp.stdin.writable():
+                self.lp.stdin.write(b"\n")
+            if self.lp.stdin.closed is False:
+                self.lp.stdin.close()
+            self.lp.wait()
+            self.open()
+
+        def _raw(self, msg):
+            if self.lp.stdin.writable():
+                self.lp.stdin.write(msg)
+            else:
+                raise Exception("Not a valid pipe for lp process")
+            if self.auto_flush:
+                self.flush()