From 5a63a0b74a5ea5344b9df1ffa39d81a8cf9916c0 Mon Sep 17 00:00:00 2001
From: Matt Westcott <matt@west.co.tt>
Date: Wed, 9 Sep 2015 17:15:38 +0100
Subject: [PATCH] Fix rounding errors when resizing 1x1 images (backport
 217e9628c73a148694641d11d1177d402d9e057c to 0.8.x)

---
 wagtail/wagtailimages/backends/base.py     |  6 +++++-
 wagtail/wagtailimages/tests/test_models.py | 22 ++++++++++++++++++++++
 wagtail/wagtailimages/tests/utils.py       |  4 ++--
 3 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/wagtail/wagtailimages/backends/base.py b/wagtail/wagtailimages/backends/base.py
index afaf550703..865b405f74 100644
--- a/wagtail/wagtailimages/backends/base.py
+++ b/wagtail/wagtailimages/backends/base.py
@@ -1,5 +1,7 @@
 from __future__ import division
 
+import math
+
 from django.conf import settings
 
 from wagtail.wagtailimages.rect import Rect
@@ -242,7 +244,9 @@ class BaseImageBackend(object):
             bottom = im_height
 
         # Crop!
-        return self.resize_to_min(self.crop(image, Rect(left, top, right, bottom)), size)
+        return self.resize_to_min(self.crop(image,
+            Rect(math.floor(left), math.floor(top), math.ceil(right), math.ceil(bottom))
+        ), size)
 
     def no_operation(self, image, param, focal_point=None):
         """Return the image unchanged"""
diff --git a/wagtail/wagtailimages/tests/test_models.py b/wagtail/wagtailimages/tests/test_models.py
index b867117c68..19c7975364 100644
--- a/wagtail/wagtailimages/tests/test_models.py
+++ b/wagtail/wagtailimages/tests/test_models.py
@@ -164,6 +164,28 @@ class TestRenditions(TestCase):
         self.assertEqual(first_rendition, second_rendition)
 
 
+class TestSinglePixelRenditions(TestCase):
+    def setUp(self):
+        # Create an image for running tests on
+        self.image = Image.objects.create(
+            title="Test image",
+            file=get_test_image_file(width=1, height=1),
+        )
+
+    def test_resize(self):
+        rendition = self.image.get_rendition('fill-100x100')
+        self.assertEqual(rendition.width, 1)
+        self.assertEqual(rendition.height, 1)
+
+        rendition = self.image.get_rendition('fill-100x150')
+        self.assertEqual(rendition.width, 1)
+        self.assertEqual(rendition.height, 1)
+
+        rendition = self.image.get_rendition('fill-150x100')
+        self.assertEqual(rendition.width, 1)
+        self.assertEqual(rendition.height, 1)
+
+
 class TestRenditionsWand(TestCase):
     def setUp(self):
         try:
diff --git a/wagtail/wagtailimages/tests/utils.py b/wagtail/wagtailimages/tests/utils.py
index 62b88126f8..e5eb3db311 100644
--- a/wagtail/wagtailimages/tests/utils.py
+++ b/wagtail/wagtailimages/tests/utils.py
@@ -9,8 +9,8 @@ from wagtail.wagtailimages.models import get_image_model
 Image = get_image_model()
 
 
-def get_test_image_file(filename='test.png'):
+def get_test_image_file(filename='test.png', width=640, height=480):
     f = BytesIO()
-    image = PIL.Image.new('RGB', (640, 480), 'white')
+    image = PIL.Image.new('RGB', (width, height), 'white')
     image.save(f, 'PNG')
     return ImageFile(f, name=filename)