add win32.send_data_to_printer() function

docs/edbob.win32.rst

@@ -0,0 +1,6 @@
+
+:mod:`edbob.win32`
+==================
+
+.. automodule:: edbob.win32
+   :members:

docs/index.rst

@@ -27,6 +27,7 @@ The following pages describe the ``edbob`` package from a caller's perspective.
    edbob.modules
    edbob.sqlalchemy
    edbob.util
+   edbob.win32
 
 
 To-Do

edbob/win32.py

@@ -33,6 +33,7 @@ if sys.platform == 'win32': # docs should build for everyone
     import pywintypes
     import win32file
     import winerror
+    import win32print
 
 
 def RegDeleteTree(key, subkey):
@@ -106,3 +107,24 @@ def file_is_free(path):
     finally:
         if handle:
             win32file.CloseHandle(handle)
+
+
+def send_data_to_printer(data, printer_name, job_name):
+    """
+    Create and submit a new print job (named ``job_name``) which sends ``data``
+    directly to the Windows printer identified by ``printer_name``.  Returns
+    the number of bytes actually written to the printer port.
+
+    This is designed for sending command strings to Zebra label printers, but
+    could potentially be useful for other situations as well.
+    """
+
+    printer = win32print.OpenPrinter(printer_name)
+    assert printer
+    assert win32print.StartDocPrinter(printer, 1, (job_name, None, None))
+    win32print.StartPagePrinter(printer)
+    num_bytes = win32print.WritePrinter(printer, data)
+    win32print.EndPagePrinter(printer)
+    win32print.EndDocPrinter(printer)
+    win32print.ClosePrinter(printer)
+    return num_bytes