From 07d47765aad69c6ee5512e3b0580b9ce1f7e95e6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20Elsd=C3=B6rfer?= <michael@elsdoerfer.com>
Date: Fri, 26 Aug 2016 10:38:36 +0200
Subject: [PATCH] Allow linespacing reset. Make this the default.

---
 src/escpos/constants.py | 1 +
 src/escpos/escpos.py    | 8 +++++++-
 test/test_functions.py  | 8 +++++++-
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/src/escpos/constants.py b/src/escpos/constants.py
index 703e48b..999dba1 100644
--- a/src/escpos/constants.py
+++ b/src/escpos/constants.py
@@ -102,6 +102,7 @@ TXT_INVERT_ON  = GS  + b'\x42\x01'  # Inverse Printing ON
 TXT_INVERT_OFF = GS  + b'\x42\x00'  # Inverse Printing OFF
 
 # Spacing
+LINESPACING_RESET = ESC + b'2'
 LINESPACING_FUNCS = {
   60: ESC + b'A',  # line_spacing/60 of an inch, 0 <= line_spacing <= 85
   360: ESC + b'+', # line_spacing/360 of an inch, 0 <= line_spacing <= 255
diff --git a/src/escpos/escpos.py b/src/escpos/escpos.py
index 99c9308..797b5ed 100644
--- a/src/escpos/escpos.py
+++ b/src/escpos/escpos.py
@@ -565,9 +565,11 @@ class Escpos(object):
         else:
             self._raw(TXT_INVERT_OFF)
 
-    def line_spacing(self, spacing=30, divisor=180):
+    def line_spacing(self, spacing=None, divisor=180):
         """ Set line character spacing.
 
+        If no spacing is given, we reset it to the default.
+
         There are different commands for setting the line spacing, using
         a different denominator:
 
@@ -578,6 +580,10 @@ class Escpos(object):
         Some printers may not support all of them. The most commonly
         available command (using a divisor of 180) is chosen.
         """
+        if spacing is None:
+            self._raw(LINESPACING_RESET)
+            return
+
         if divisor not in LINESPACING_FUNCS:
             raise ValueError("divisor must be either 360, 180 or 60")
         if (divisor in [360, 180] \
diff --git a/test/test_functions.py b/test/test_functions.py
index a78cc14..f35de54 100644
--- a/test/test_functions.py
+++ b/test/test_functions.py
@@ -8,10 +8,16 @@ def test_line_spacing_code_gen():
     assert printer.output == '\x1b3\n'
 
 
+def test_line_spacing_rest():
+    printer = Dummy()
+    printer.line_spacing()
+    assert printer.output == '\x1b2'
+
+
 def test_line_spacing_error_handling():
     printer = Dummy()
     with assert_raises(ValueError):
-      printer.line_spacing(divisor=44)
+      printer.line_spacing(99, divisor=44)
     with assert_raises(ValueError):
       printer.line_spacing(divisor=80, spacing=86)
     with assert_raises(ValueError):