Fix outermost path detection

The code which detects the outermost contour assumed that later paths would be contained within earlier paths, which is of course rubbish. Paths can be in any order they like, so we have to do the O(n^2) thing to find the outermost ones.

com.google.fonts/check/outline_direction
On the Outline profile.

(issue #4719 and googlefonts/fontmake#1093)

CHANGELOG.md

@@ -2,8 +2,9 @@ Below are the noteworthy changes from each release.
 A more detailed list of changes is available in the corresponding milestones for each release in the Github issue tracker (https://github.com/googlefonts/fontbakery/milestones?state=closed).
 
 ## Upcoming release: 0.12.7 (2024-May-??)
-  - ...
 
+#### On the Outline profile
+  - **[com.google.fonts/check/outline_direction]:** fixed an error where the outermost path was not correctly detected. (issue #4719)
 
 ## 0.12.6 (2024-May-13)
   - Fixed race condition with `--auto-jobs` caused by the current working directory changing (issue #4700)

Lib/fontbakery/checks/outline.py

@@ -355,7 +355,9 @@ def bounds_contains(bb1, bb2):
         outline_bounds = [path.bounds() for path in outlines]
         is_within = defaultdict(list)
         for i, my_bounds in enumerate(outline_bounds):
-            for j in range(i + 1, len(outline_bounds)):
+            for j in range(0, len(outline_bounds)):
+                if i == j:
+                    continue
                 their_bounds = outline_bounds[j]
                 if bounds_contains(my_bounds, their_bounds):
                     is_within[j].append(i)

tests/checks/outline_test.py

@@ -150,3 +150,6 @@ def test_check_outline_direction():
     assert_results_contain(results, WARN, "ccw-outer-contour")
     messages = "".join([m.message.message for m in results])
     assert "A (U+0041) has a counter-clockwise outer contour" in messages
+
+    font = TEST_FILE("wonky_paths/OutlineTest.ttf")
+    assert_PASS(check(font))