From eeb9e719e33b26907cbfbf859d4c9e0c3224307c Mon Sep 17 00:00:00 2001
From: Andrew Murray <radarhere@users.noreply.github.com>
Date: Sun, 7 Jun 2020 12:07:13 +1000
Subject: [PATCH] Fixed drawing a 1px high polygon

---
 Tests/images/imagedraw_polygon_1px_high.png | Bin 0 -> 73 bytes
 Tests/test_imagedraw.py                     |  14 ++++++++++++++
 src/libImaging/Draw.c                       |   6 +++---
 3 files changed, 17 insertions(+), 3 deletions(-)
 create mode 100644 Tests/images/imagedraw_polygon_1px_high.png

diff --git a/Tests/images/imagedraw_polygon_1px_high.png b/Tests/images/imagedraw_polygon_1px_high.png
new file mode 100644
index 0000000000000000000000000000000000000000..e06508a0af0a8baa0adeed753157ad0b0536664e
GIT binary patch
literal 73
zcmeAS@N?(olHy`uVBq!ia0vp^%plCc1SD^IDZKzv0-i38Ar*6y6B-zg{pXQjU=WsP
VWZd*(1qV=$!PC{xWt~$(69Dik5B>lE

literal 0
HcmV?d00001

diff --git a/Tests/test_imagedraw.py b/Tests/test_imagedraw.py
index 7ecec48d3..74b0b8ff3 100644
--- a/Tests/test_imagedraw.py
+++ b/Tests/test_imagedraw.py
@@ -531,6 +531,20 @@ def test_polygon_kite():
         assert_image_equal(im, Image.open(expected))
 
 
+def test_polygon_1px_high():
+    # Test drawing a 1px high polygon
+    # Arrange
+    im = Image.new("RGB", (3, 3))
+    draw = ImageDraw.Draw(im)
+    expected = "Tests/images/imagedraw_polygon_1px_high.png"
+
+    # Act
+    draw.polygon([(0, 1), (0, 1), (2, 1), (2, 1)], "#f00")
+
+    # Assert
+    assert_image_equal(im, Image.open(expected))
+
+
 def helper_rectangle(bbox):
     # Arrange
     im = Image.new("RGB", (W, H))
diff --git a/src/libImaging/Draw.c b/src/libImaging/Draw.c
index 10aaae1f2..947d7f70f 100644
--- a/src/libImaging/Draw.c
+++ b/src/libImaging/Draw.c
@@ -489,15 +489,15 @@ polygon_generic(Imaging im, int n, Edge *e, int ink, int eofill,
     }
 
     for (i = 0; i < n; i++) {
-        if (e[i].ymin == e[i].ymax) {
-            continue;
-        }
         if (ymin > e[i].ymin) {
             ymin = e[i].ymin;
         }
         if (ymax < e[i].ymax) {
             ymax = e[i].ymax;
         }
+        if (e[i].ymin == e[i].ymax) {
+            continue;
+        }
         edge_table[edge_count++] = (e + i);
     }
     if (ymin < 0) {