From bbcfa44e5475caf2871c084494ce034130d85109 Mon Sep 17 00:00:00 2001
From: Neil <neil@zotac.akihabara.co.uk>
Date: Tue, 17 Mar 2015 21:57:06 +0900
Subject: [PATCH] Use string joins instead of concatenation for efficiency.

---
 lib/bmp.py | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/lib/bmp.py b/lib/bmp.py
index e8302ec06..1db955d24 100644
--- a/lib/bmp.py
+++ b/lib/bmp.py
@@ -174,12 +174,13 @@ class BitMap(object):
 
     # write pixels
     self.bitarray.reverse()
+    rows = []
     for row in self.bitarray:
       for pixel in row:
         c = self.palette[pixel]
-        _bitmap += long24ToString(c)
-      for i in range(line_padding):
-        _bitmap += chr( 0 )
+        rows.append(long24ToString(c))
+      rows.append(chr(0) * line_padding)
+    _bitmap += ''.join(rows)
 
     return _bitmap