matplotlib · FazeelUsmani · Apr 22, 2026 · Apr 23, 2026 · rcomer · Apr 22, 2026
diff --git a/lib/matplotlib/tests/test_text.py b/lib/matplotlib/tests/test_text.py
@@ -753,6 +753,47 @@ def test_wrap_no_wrap():
     assert text._get_wrapped_text() == 'non wrapped text'
 
 
+@pytest.mark.parametrize(
+    "x, y, rotation",
+    [(0.0, 1.0, 0),
+     (1.0, 0.5, 90),
+     (0.5, 1.0, 180),
+     (0.0, 0.5, 270)])
+def test_wrap_on_figure_edge(x, y, rotation):
+    # Regression test for #31537 - wrap collapsed to zero on figure edges.
+    s = 'This is a very long text that should be wrapped multiple times.'
+    fig = plt.figure(figsize=(6, 4))
+    t = fig.text(x, y, s, wrap=True, rotation=rotation)
+    fig.canvas.draw()
+
+    # Compare to a nudged-off-the-edge reference that should wrap the same.
+    nudge = 1e-4
+    x_ref = x - nudge if x == 1.0 else x + nudge if x == 0.0 else x
+    y_ref = y - nudge if y == 1.0 else y + nudge if y == 0.0 else y
+    fig_ref = plt.figure(figsize=(6, 4))
+    t_ref = fig_ref.text(x_ref, y_ref, s, wrap=True, rotation=rotation)
+    fig_ref.canvas.draw()
+
+    assert t._get_wrapped_text() == t_ref._get_wrapped_text()
+
+
+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))
+    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.canvas.draw()
+    assert any(' ' in line for line in t._get_wrapped_text().split('\n'))
+
+
 @check_figures_equal()
 def test_buffer_size(fig_test, fig_ref):
     # On old versions of the Agg renderer, large non-ascii single-character

diff --git a/lib/matplotlib/text.py b/lib/matplotlib/text.py
@@ -757,6 +757,21 @@ 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:
+            return figure_box.x1 - x0
+        if abs(rotation - 90) < tol:
+            return figure_box.y1 - y0
+        if abs(rotation - 180) < tol:
+            return x0 - figure_box.x0
+        if abs(rotation - 270) < tol:
+            return y0 - figure_box.y0
+
         if rotation > 270:
             quad = rotation - 270
             h1 = (y0 - figure_box.y0) / math.cos(math.radians(quad))