FIX: clamp get_rotation to [0, 360) when transform_rotates_text

FazeelUsmani · FazeelUsmani · commit a2411fad5f05 · 2026-04-23T14:42:20.000+05:30
transform_angles can return a tiny-negative value, and in Python (tiny_negative) % 360 float-rounds to exactly 360.0, breaking the [0, 360) range that the docstring promises. Clamp 360 back to 0 so callers can rely on the documented range. With that in place, the normalize + tolerance wrapper added to _get_dist_to_box in the previous commit is no longer needed. Reduce it to plain cardinal-angle short-circuits, per rcomer's suggestion in #31537. Rework the transform_rotates_text regression test to compare wrapped output against a plain rotation=0 reference at the same position, instead of the weaker "contains a space" assertion.
diff --git a/lib/matplotlib/tests/test_text.py b/lib/matplotlib/tests/test_text.py
@@ -778,20 +778,22 @@ def test_wrap_on_figure_edge(x, y, rotation):
 
 
 def test_wrap_on_figure_edge_transform_rotates_text():
-    # With transform_rotates_text=True, get_rotation() goes through
-    # transform_angles() and can return near-cardinal angles with float
-    # noise (e.g. -90.00000000000003 for a 270 degree rotation), which
-    # used to skip the cardinal-angle short-circuit in _get_dist_to_box.
-    from matplotlib.transforms import Affine2D
-    fig = plt.figure(figsize=(6, 4))
+    # Regression test for #31537 - transform_rotates_text with an axis-aligned
+    # transform can make get_rotation() float-round to 360.0.
     s = 'This is a very long text that should be wrapped multiple times.'
-    # rotate_deg(90).rotate_deg(-90) is identity geometrically, but carries
-    # enough numerical slop to perturb transform_angles.
-    transform = Affine2D().rotate_deg(90).rotate_deg(-90) + fig.transFigure
-    t = fig.text(0.0, 0.5, s, transform=transform, wrap=True, rotation=270,
-                 transform_rotates_text=True)
+
+    fig = plt.figure(figsize=(6, 4))
+    transform = mtransforms.Affine2D().rotate_deg(270) + fig.transFigure
+    t = fig.text(0.0, 0.0, s, transform=transform, wrap=True,
+                 rotation=90, transform_rotates_text=True)
     fig.canvas.draw()
-    assert any(' ' in line for line in t._get_wrapped_text().split('\n'))
+
+    fig_ref = plt.figure(figsize=(6, 4))
+    t_ref = fig_ref.text(0.0, 0.0, s, wrap=True, rotation=0)
+    fig_ref.canvas.draw()
+
+    assert 0 <= t.get_rotation() < 360
+    assert t._get_wrapped_text() == t_ref._get_wrapped_text()
 
 
 @check_figures_equal()
diff --git a/lib/matplotlib/text.py b/lib/matplotlib/text.py
@@ -339,8 +339,10 @@ def _char_index_at(self, x):
     def get_rotation(self):
         """Return the text angle in degrees in the range [0, 360)."""
         if self.get_transform_rotates_text():
-            return self.get_transform().transform_angles(
+            angle = self.get_transform().transform_angles(
                 [self._rotation], [self.get_unitless_position()]).item(0) % 360
+            # `(tiny_negative) % 360` can float-round to exactly 360.0.
+            return 0.0 if angle == 360 else angle
         else:
             return self._rotation
 
@@ -757,19 +759,15 @@ def _get_dist_to_box(self, rotation, x0, y0, figure_box):
         Return the distance from the given points to the boundaries of a
         rotated box, in pixels.
         """
-        # Normalize rotation; transform_angles can return values outside
-        # [0, 360) with tiny float noise.
-        rotation = rotation % 360
-        # Short-circuit cardinal angles, otherwise cos(radians(90)) makes
-        # the trig formula below blow up when the text is on the edge.
-        tol = 1e-10
-        if rotation < tol or rotation > 360 - tol:
+        # Short-circuit cardinals; otherwise cos(radians(90)) makes the trig
+        # formula below blow up when the text is on the matching edge.
+        if rotation == 0:
             return figure_box.x1 - x0
-        if abs(rotation - 90) < tol:
+        if rotation == 90:
             return figure_box.y1 - y0
-        if abs(rotation - 180) < tol:
+        if rotation == 180:
             return x0 - figure_box.x0
-        if abs(rotation - 270) < tol:
+        if rotation == 270:
             return y0 - figure_box.y0
 
         if rotation > 270:
