Fix joining rounded rectangle corners (#9384)

Author: hugovk

Tests/images/imagedraw_rounded_rectangle_radius.png

@@ -895,6 +895,18 @@ def test_rounded_rectangle_joined_x_different_corners() -> None:
     )
 
 
+def test_rounded_rectangle_radius() -> None:
+    # Arrange
+    im = Image.new("RGB", (W, H))
+    draw = ImageDraw.Draw(im, "RGB")
+
+    # Act
+    draw.rounded_rectangle((25, 25, 75, 75), 24, fill="red", outline="green", width=5)
+
+    # Assert
+    assert_image_equal_tofile(im, "Tests/images/imagedraw_rounded_rectangle_radius.png")
+
+
 @pytest.mark.parametrize(
     "xy, radius, type",
     [

Tests/test_imagedraw.py

@@ -487,7 +487,7 @@ def draw_corners(pieslice: bool) -> None:
 
             if full_x:
                 self.draw.draw_rectangle((x0, y0 + r + 1, x1, y1 - r - 1), fill_ink, 1)
-            elif x1 - r - 1 > x0 + r + 1:
+            elif x1 - r - 1 >= x0 + r + 1:
                 self.draw.draw_rectangle((x0 + r + 1, y0, x1 - r - 1, y1), fill_ink, 1)
             if not full_x and not full_y:
                 left = [x0, y0, x0 + r, y1]