Add warning when using negative rect dimensions in draw module

docs/reST/ref/draw.rst

@@ -276,7 +276,8 @@ object around the draw calls (see :func:`pygame.Surface.lock` and
    :type color: Color or string (for :doc:`color_list`) or int or tuple(int, int, int, [int])
    :param Rect rect: rectangle to indicate the position and dimensions of the
       ellipse, the ellipse will be centered inside the rectangle and bounded
-      by it
+      by it. Negative rect dimension values are deprecated, and will raise an exception
+      in a future versions on pygame-ce.
    :param int width: (optional) used for line thickness or to indicate that
       the ellipse is to be filled (not to be confused with the width value
       of the ``rect`` parameter)
@@ -296,6 +297,7 @@ object around the draw calls (see :func:`pygame.Surface.lock` and
    :rtype: Rect
 
    .. versionchangedold:: 2.0.0 Added support for keyword arguments.
+   .. versionchanged:: 2.5.2 Negative rect dimension values will raise a deprecation warning
 
    .. ## pygame.draw.ellipse ##
 

src_c/draw.c

@@ -716,14 +716,25 @@ ellipse(PyObject *self, PyObject *arg, PyObject *kwargs)
         return RAISE(PyExc_RuntimeError, "error locking surface");
     }
 
-    if (!width ||
-        width >= MIN(rect->w / 2 + rect->w % 2, rect->h / 2 + rect->h % 2)) {
-        draw_ellipse_filled(surf, rect->x, rect->y, rect->w, rect->h, color,
-                            drawn_area);
+    if (rect->w < 0 || rect->h < 0) {
+        if (PyErr_WarnEx(PyExc_DeprecationWarning,
+                         "Negative rect dimension values are deprecated and "
+                         "have no functionality. This will cause an error in "
+                         "a future version of pygame-ce.",
+                         1) == -1) {
+            return pgRect_New4(0, 0, 0, 0);
+        }
     }
     else {
-        draw_ellipse_thickness(surf, rect->x, rect->y, rect->w, rect->h,
-                               width - 1, color, drawn_area);
+        if (!width || width >= MIN(rect->w / 2 + rect->w % 2,
+                                   rect->h / 2 + rect->h % 2)) {
+            draw_ellipse_filled(surf, rect->x, rect->y, rect->w, rect->h,
+                                color, drawn_area);
+        }
+        else {
+            draw_ellipse_thickness(surf, rect->x, rect->y, rect->w, rect->h,
+                                   width - 1, color, drawn_area);
+        }
     }
 
     if (!pgSurface_Unlock(surfobj)) {

test/draw_test.py

@@ -408,6 +408,20 @@ def test_ellipse__valid_width_values(self):
             self.assertEqual(surface.get_at(pos), expected_color)
             self.assertIsInstance(bounds_rect, pygame.Rect)
 
+    def test_ellipse__negative_rect_warning(self):
+        """Ensures draw ellipse shows DeprecationWarning for rect with negative values"""
+        # Generate few faulty rects.
+        faulty_rects = ((10, 10, -5, 3), (10, 10, 5, -3))
+        with warnings.catch_warnings(record=True) as w:
+            for count, rect in enumerate(faulty_rects):
+                # Cause all warnings to always be triggered.
+                warnings.simplefilter("always")
+                # Trigger DeprecationWarning.
+                self.draw_ellipse(pygame.Surface((6, 6)), (255, 255, 255), rect)
+                # Check if there is only one warning and is a DeprecationWarning.
+                self.assertEqual(len(w), count + 1)
+                self.assertTrue(issubclass(w[-1].category, DeprecationWarning))
+
     def test_ellipse__valid_rect_formats(self):
         """Ensures draw ellipse accepts different rect formats."""
         pos = (1, 1)