Move the image loader to shared

pytools/font.py

@@ -25,14 +25,7 @@ def main(font_name, n_glyphs, fname_png, fname_c):
 
 
 def load_glyphs(fname_png: str):
-    with Image.open(fname_png) as im:
-        width = im.width
-        height = im.height
-
-        assert width % 8 == 0, "width must be a multiple of 8"
-        assert height % 8 == 0, "height must be a multiple of 8"
-
-        data = list(im.convert("RGBA").getdata())
+    width, height, data = shared.load_image(fname_png)
     monochrome = [pixel_to_monochrome(p) for p in data]
 
     glyphs = []

pytools/shared.py

@@ -1,6 +1,17 @@
+from PIL import Image
 from jinja2 import Environment, BaseLoader, select_autoescape
 
 templates = Environment(
     loader=BaseLoader(),
     autoescape=select_autoescape(),
 )
+
+def load_image(fname):
+    with Image.open(fname) as im:
+        width = im.width
+        height = im.height
+
+        assert width % 8 == 0, "width must be a multiple of 8"
+        assert height % 8 == 0, "height must be a multiple of 8"
+
+        return width, height, list(im.convert("RGBA").getdata())