Merge pull request #145 from googlefonts/img-diff

Output images with difference blend mode

src/diffenator2/__main__.py

@@ -58,9 +58,9 @@ def main(**kwargs):
         )
         diff_parser.add_argument("--no-diffenator", default=False, action="store_true")
         diff_parser.add_argument("--threshold", "-t", type=float, default=THRESHOLD)
-        diff_parser.add_argument("--precision", default=FONT_SIZE)
+        diff_parser.add_argument("--precision", default=FONT_SIZE, type=int)
         # TODO this can just be precision
-        diff_parser.add_argument("--font-size", default=FONT_SIZE)
+        diff_parser.add_argument("--font-size", default=FONT_SIZE, type=int)
         diff_parser.add_argument(
             "--no-tables", action="store_true", help="Skip diffing font tables"
         )

src/diffenator2/screenshot.py

@@ -53,6 +53,7 @@ def take_png(self, browser: any, dst_dir: str, javascript: str = ""):
         body_el = browser.find_element(By.TAG_NAME, "html")
         browser.set_window_size(self.width, body_el.size["height"])
         browser.save_screenshot(filename)
+        return filename
 
     def take_gif(self, url: str, dst_dir: str, font_toggle):
         before_fp = os.path.join(dst_dir, "before")

src/diffenator2/utils.py

@@ -125,8 +125,6 @@ def gen_gifs(dir1: str, dir2: str, dst_dir: str):
     dir2_imgs = set(f for f in os.listdir(dir2) if f.endswith(("jpg", "png")))
     shared_imgs = dir1_imgs & dir2_imgs
     for img in shared_imgs:
-        # We use apng format since a gif's dimensions are limited to 64kx64k
-        # we have encountered many diffs which are taller than this.
         gif_filename = img[:-4] + ".gif"
         img_a_path = os.path.join(dir1, img)
         img_b_path = os.path.join(dir2, img)
@@ -146,6 +144,15 @@ def gen_gif(img_a, img_b, dst):
     img_a = img_a.crop(crop_box)
     img_b = img_b.crop(crop_box)
     img_a.save(dst, save_all=True, append_images=[img_b], loop=10000, duration=1000)
+    gen_img_difference(img_a, img_b, dst.replace(".gif", "_diff.png"))
+
+
+def gen_img_difference(img_a, img_b, dst: str):
+    from PIL import ImageChops
+    img_a = img_a.convert("RGB")
+    img_b = img_b.convert("RGB")
+    img = ImageChops.difference(img_a, img_b)
+    img.save(dst)
 
 
 @lru_cache()

tests/test_functional.py

@@ -46,7 +46,7 @@ def test_run_diffbrowsers_proof_imgs(fp):
                 else:
                     imgs.append(f)
         # There should be images for the text, glyphs and waterfall page
-        assert len(imgs) == 3
+        assert len(imgs) >= 3