Move checkerboard_image to imagetools.

etiquette/helpers.py

@@ -124,30 +124,6 @@ def album_photos_as_filename_map(
 
     return arcnames
 
-def checkerboard_image(color_1, color_2, image_size, checker_size) -> PIL.Image:
-    '''
-    Generate a PIL Image with a checkerboard pattern.
-
-    color_1:
-        The color starting in the top left. Either RGB tuple or a string
-        that PIL understands.
-    color_2:
-        The alternate color
-    image_size:
-        Tuple of two integers, the image size in pixels.
-    checker_size:
-        Tuple of two integers, the size of each checker in pixels.
-    '''
-    image = PIL.Image.new('RGB', image_size, color_1)
-    checker = PIL.Image.new('RGB', (checker_size, checker_size), color_2)
-    offset = True
-    for y in range(0, image_size[1], checker_size):
-        for x in range(0, image_size[0], checker_size * 2):
-            x += offset * checker_size
-            image.paste(checker, (x, y))
-        offset = not offset
-    return image
-
 def decollide_names(things, namer):
     '''
     When generating zip files, or otherwise exporting photos to disk, it is
@@ -221,7 +197,7 @@ def generate_image_thumbnail(filepath, width, height) -> PIL.Image:
         image = image.resize((new_width, new_height))
 
     if image.mode == 'RGBA':
-        background = checkerboard_image(
+        background = imagetools.checkerboard_image(
             color_1=(256, 256, 256),
             color_2=(128, 128, 128),
             image_size=image.size,