From f93b605b758f210b368c7b3585976aea52fab261 Mon Sep 17 00:00:00 2001
From: Luflosi <luflosi@luflosi.de>
Date: Fri, 18 Oct 2019 21:26:11 +0200
Subject: [PATCH] Fix line drawing algorithm

---
 kitty/fonts/box_drawing.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kitty/fonts/box_drawing.py b/kitty/fonts/box_drawing.py
index e87109612..d03f5bec9 100644
--- a/kitty/fonts/box_drawing.py
+++ b/kitty/fonts/box_drawing.py
@@ -238,9 +238,13 @@ def antialiased_1px_line(buf, width, height, p1, p2):
     grad = dy/dx
     intery = y1 + rfpart(x1) * grad
 
-    xstart = draw_endpoint(p(*p1)) + 1
+    xstart = draw_endpoint(p(*p1))
     xend = draw_endpoint(p(*p2))
 
+    if xstart > xend:
+        xstart, xend = xend, xstart
+    xstart += 1
+
     for x in range(xstart, xend):
         y = int(intery)
         putpixel(p(x, y), rfpart(intery))