Use Pillow >= 10.1 default font_size support in utils.draw_bounding_boxes

Author: stevepapazis

test/assets/fakedata/draw_boxes_default_font_size15.png

@@ -193,6 +193,21 @@ def test_draw_boxes_with_coloured_label_text_boxes():
     assert_equal(result, expected)
 
 
+@pytest.mark.skipif(PILLOW_VERSION < (10, 1), reason="The reference image is only valid for PIL >= 10.1")
+@pytest.mark.parametrize("font_size", [None, 15, 20])
+def test_draw_boxes_with_default_font_size(font_size):
+    img = torch.full((3, 100, 100), 255, dtype=torch.uint8)
+    labels = ["a", "b", "c", "d"]
+    colors = ["green", "#FF00FF", (0, 255, 0), "red"]
+    result = utils.draw_bounding_boxes(img, boxes, labels=labels, colors=colors, fill=True, font_size=font_size)
+
+    path = os.path.join(
+        os.path.dirname(os.path.abspath(__file__)), "assets", "fakedata", f"draw_boxes_default_font_size{font_size}.png"
+    )
+    expected = torch.as_tensor(np.array(Image.open(path))).permute(2, 0, 1)
+    assert_equal(result, expected)
+
+
 @pytest.mark.skipif(PILLOW_VERSION < (10, 1), reason="The reference image is only valid for PIL >= 10.1")
 def test_draw_rotated_boxes():
     img = torch.full((3, 500, 500), 255, dtype=torch.uint8)
@@ -289,10 +304,15 @@ def test_draw_invalid_boxes():
         utils.draw_bounding_boxes(img_correct, boxes_wrong)
 
 
+@pytest.mark.skipif(PILLOW_VERSION >= (10, 1), reason="The warning is only valid for PIL < 10.1")
 def test_draw_boxes_warning():
     img = torch.full((3, 100, 100), 255, dtype=torch.uint8)
 
-    with pytest.warns(UserWarning, match=re.escape("Argument 'font_size' will be ignored since 'font' is not set.")):
+    warning_txt = (
+        "Argument 'font_size' will be ignored since 'font' is not set. "
+        "To use 'font_size' with the default font, please upgrade to Pillow >= 10.1."
+    )
+    with pytest.warns(UserWarning, match=re.escape(warning_txt)):
         utils.draw_bounding_boxes(img, boxes, font_size=11)
 
 

test/assets/fakedata/draw_boxes_default_font_size20.png

@@ -371,9 +371,23 @@ def draw_bounding_boxes(
         label_background_colors = colors.copy()  # type: ignore[assignment]
 
     if font is None:
-        if font_size is not None:
-            warnings.warn("Argument 'font_size' will be ignored since 'font' is not set.")
-        txt_font = ImageFont.load_default()
+        # This may throw if the version string is from an install that comes from a
+        # non-stable or development version. We'll fall back to the old behavior in
+        # such cases.
+        try:
+            PILLOW_VERSION = tuple(int(x) for x in PILLOW_VERSION_STRING.split("."))
+        except Exception:
+            PILLOW_VERSION = None
+
+        if PILLOW_VERSION is None or PILLOW_VERSION < (10, 1):
+            if font_size is not None:
+                warnings.warn(
+                    "Argument 'font_size' will be ignored since 'font' is not set. "
+                    "To use 'font_size' with the default font, please upgrade to Pillow >= 10.1."
+                )
+            txt_font = ImageFont.load_default()
+        else:
+            txt_font = ImageFont.load_default(size=font_size)
     else:
         txt_font = ImageFont.truetype(font=font, size=font_size or 10)