Refactored crop_to_centre actions to use a utils method

wagtail/wagtailimages/backends/pillow.py

@@ -1,8 +1,10 @@
 from __future__ import absolute_import
 
-from .base import BaseImageBackend
 import PIL.Image
 
+from wagtail.wagtailimages.backends.base import BaseImageBackend
+from wagtail.wagtailimages.utils.crop import crop_to_centre
+
 
 class PillowBackend(BaseImageBackend):
     def __init__(self, params):
@@ -21,18 +23,9 @@ class PillowBackend(BaseImageBackend):
         return image.resize(size, PIL.Image.ANTIALIAS)
 
     def crop_to_centre(self, image, size):
-        (original_width, original_height) = image.size
-        (target_width, target_height) = size
+        crop_box = crop_to_centre(image.size, size)
 
-        # final dimensions should not exceed original dimensions
-        final_width = min(original_width, target_width)
-        final_height = min(original_height, target_height)
-
-        if final_width == original_width and final_height == original_height:
+        if crop_box.size != image.size:
+            return image.crop(crop_box)
+        else:
             return image
-
-        left = (original_width - final_width) / 2
-        top = (original_height - final_height) / 2
-        return image.crop(
-            (left, top, left + final_width, top + final_height)
-        )

wagtail/wagtailimages/backends/wand.py

@@ -1,9 +1,11 @@
 from __future__ import absolute_import
 
-from .base import BaseImageBackend
 from wand.image import Image
 from wand.api import library
 
+from wagtail.wagtailimages.backends.base import BaseImageBackend
+from wagtail.wagtailimages.utils.crop import crop_to_centre
+
 
 class WandBackend(BaseImageBackend):
     def __init__(self, params):
@@ -25,21 +27,13 @@ class WandBackend(BaseImageBackend):
         return new_image
 
     def crop_to_centre(self, image, size):
-        (original_width, original_height) = image.size
-        (target_width, target_height) = size
+        crop_box = crop_to_centre(image.size, size)
 
-        # final dimensions should not exceed original dimensions
-        final_width = min(original_width, target_width)
-        final_height = min(original_height, target_height)
-
-        if final_width == original_width and final_height == original_height:
+        if crop_box.size != image.size:
+            new_image = image.clone()
+            new_image.crop(
+                left=crop_box[0], top=crop_box[1], right=crop_box[2], bottom=crop_box[3]
+            )
+            return new_image
+        else:
             return image
-
-        left = (original_width - final_width) / 2
-        top = (original_height - final_height) / 2
-
-        new_image = image.clone()
-        new_image.crop(
-            left=left, top=top, right=left + final_width, bottom=top + final_height
-        )
-        return new_image

wagtail/wagtailimages/utils/crop.py

@@ -0,0 +1,35 @@
+class CropBox(object):
+    def __init__(self, left, top, right, bottom):
+        self.left = int(left)
+        self.top = int(top)
+        self.right = int(right)
+        self.bottom = int(bottom)
+
+    def __getitem__(self, key):
+        return (self.left, self.top, self.right, self.bottom)[key]
+
+    @property
+    def width(self):
+        return self.right - self.left
+
+    @property
+    def height(self):
+        return self.bottom - self.top
+
+    @property
+    def size(self):
+        return self.width, self.height
+
+
+def crop_to_centre(image_size, crop_size):
+    (original_width, original_height) = image_size
+    (crop_width, crop_height) = crop_size
+
+    # final dimensions should not exceed original dimensions
+    final_width = min(original_width, crop_width)
+    final_height = min(original_height, crop_height)
+
+    left = (original_width - final_width) / 2
+    top = (original_height - final_height) / 2
+
+    return CropBox(left, top, left + final_width, top + final_height)