Merge pull request #13419 from jklymak/fix-secondary-axis-resize

dstansby · web-flow · commit daaf978ff52b · 2019-02-14T09:48:28.000Z
FIX: secondary_axis resize
diff --git a/lib/matplotlib/axes/_secondary_axes.py b/lib/matplotlib/axes/_secondary_axes.py
@@ -43,11 +43,12 @@ def _make_secondary_locator(rect, parent):
     *parent*.
     """
     _rect = mtransforms.Bbox.from_bounds(*rect)
-    bb = mtransforms.TransformedBbox(_rect, parent.transAxes)
-    tr = parent.figure.transFigure.inverted()
-    bb = mtransforms.TransformedBbox(bb, tr)
-
     def secondary_locator(ax, renderer):
+        # delay evaluating transform until draw time because the
+        # parent transform may have changed (i.e. if window reesized)
+        bb = mtransforms.TransformedBbox(_rect, parent.transAxes)
+        tr = parent.figure.transFigure.inverted()
+        bb = mtransforms.TransformedBbox(bb, tr)
         return bb
 
     return secondary_locator
diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -6106,3 +6106,16 @@ def test_secondary_fail():
         axsec = ax.secondary_xaxis('right')
     with pytest.raises(ValueError):
         axsec = ax.secondary_yaxis('bottom')
+
+
+def test_secondary_resize():
+    fig, ax = plt.subplots(figsize=(10, 5))
+    ax.plot(np.arange(2, 11), np.arange(2, 11))
+    def invert(x):
+        with np.errstate(divide='ignore'):
+            return 1 / x
+
+    axsec = ax.secondary_xaxis('top', functions=(invert, invert))
+    fig.canvas.draw()
+    fig.set_size_inches((7, 4))
+    assert_allclose(ax.get_position().extents, [0.125, 0.1, 0.9, 0.9])
