Round down the radius in rounded_rectangle

Tests/test_imagedraw.py

@@ -722,6 +722,29 @@ def test_rounded_rectangle(xy):
     assert_image_equal_tofile(im, "Tests/images/imagedraw_rounded_rectangle.png")
 
 
+@pytest.mark.parametrize(
+    "xy, radius, type",
+    [
+        ((10, 20, 190, 180), 30.5, "given"),
+        ((10, 10, 181, 190), 90, "width"),
+        ((10, 20, 190, 181), 85, "height"),
+    ],
+)
+def test_rounded_rectangle_non_integer_radius(xy, radius, type):
+    # Arrange
+    im = Image.new("RGB", (200, 200))
+    draw = ImageDraw.Draw(im)
+
+    # Act
+    draw.rounded_rectangle(xy, radius, fill="red", outline="green", width=5)
+
+    # Assert
+    assert_image_equal_tofile(
+        im,
+        "Tests/images/imagedraw_rounded_rectangle_non_integer_radius_" + type + ".png",
+    )
+
+
 def test_rounded_rectangle_zero_radius():
     # Arrange
     im = Image.new("RGB", (W, H))

src/PIL/ImageDraw.py

@@ -282,6 +282,7 @@ class ImageDraw:
             # If the corners have no curve, that is a rectangle
             return self.rectangle(xy, fill, outline, width)
 
+        r = d // 2
         ink, fill = self._getink(outline, fill)
 
         def draw_corners(pieslice):
@@ -315,36 +316,28 @@ class ImageDraw:
             draw_corners(True)
 
             if full_x:
-                self.draw.draw_rectangle(
+                self.draw.draw_rectangle((x0, y0 + r + 1, x1, y1 - r - 1), fill, 1)
-                    (x0, y0 + d / 2 + 1, x1, y1 - d / 2 - 1), fill, 1
-                )
             else:
-                self.draw.draw_rectangle(
+                self.draw.draw_rectangle((x0 + r + 1, y0, x1 - r - 1, y1), fill, 1)
-                    (x0 + d / 2 + 1, y0, x1 - d / 2 - 1, y1), fill, 1
-                )
             if not full_x and not full_y:
-                self.draw.draw_rectangle(
+                self.draw.draw_rectangle((x0, y0 + r + 1, x0 + r, y1 - r - 1), fill, 1)
-                    (x0, y0 + d / 2 + 1, x0 + d / 2, y1 - d / 2 - 1), fill, 1
+                self.draw.draw_rectangle((x1 - r, y0 + r + 1, x1, y1 - r - 1), fill, 1)
-                )
-                self.draw.draw_rectangle(
-                    (x1 - d / 2, y0 + d / 2 + 1, x1, y1 - d / 2 - 1), fill, 1
-                )
         if ink is not None and ink != fill and width != 0:
             draw_corners(False)
 
             if not full_x:
                 self.draw.draw_rectangle(
-                    (x0 + d / 2 + 1, y0, x1 - d / 2 - 1, y0 + width - 1), ink, 1
+                    (x0 + r + 1, y0, x1 - r - 1, y0 + width - 1), ink, 1
                 )
                 self.draw.draw_rectangle(
-                    (x0 + d / 2 + 1, y1 - width + 1, x1 - d / 2 - 1, y1), ink, 1
+                    (x0 + r + 1, y1 - width + 1, x1 - r - 1, y1), ink, 1
                 )
             if not full_y:
                 self.draw.draw_rectangle(
-                    (x0, y0 + d / 2 + 1, x0 + width - 1, y1 - d / 2 - 1), ink, 1
+                    (x0, y0 + r + 1, x0 + width - 1, y1 - r - 1), ink, 1
                 )
                 self.draw.draw_rectangle(
-                    (x1 - width + 1, y0 + d / 2 + 1, x1, y1 - d / 2 - 1), ink, 1
+                    (x1 - width + 1, y0 + r + 1, x1, y1 - r - 1), ink, 1
                 )
 
     def _multiline_check(self, text):