Merge pull request matplotlib#21519 from anntzer/mi

mark_inset should manually unstale axes limits before drawing itself.

Author: jklymak

lib/mpl_toolkits/axes_grid1/inset_locator.py

@@ -579,6 +579,22 @@ def zoomed_inset_axes(parent_axes, zoom, loc='upper right',
     return inset_axes
 
 
+class _TransformedBboxWithCallback(TransformedBbox):
+    """
+    Variant of `.TransformBbox` which calls *callback* before returning points.
+
+    Used by `.mark_inset` to unstale the parent axes' viewlim as needed.
+    """
+
+    def __init__(self, *args, callback, **kwargs):
+        super().__init__(*args, **kwargs)
+        self._callback = callback
+
+    def get_points(self):
+        self._callback()
+        return super().get_points()
+
+
 @docstring.dedent_interpd
 def mark_inset(parent_axes, inset_axes, loc1, loc2, **kwargs):
     """
@@ -613,7 +629,9 @@ def mark_inset(parent_axes, inset_axes, loc1, loc2, **kwargs):
     p1, p2 : `matplotlib.patches.Patch`
         The patches connecting two corners of the inset axes and its area.
     """
-    rect = TransformedBbox(inset_axes.viewLim, parent_axes.transData)
+    rect = _TransformedBboxWithCallback(
+        inset_axes.viewLim, parent_axes.transData,
+        callback=parent_axes._unstale_viewLim)
 
     if 'fill' in kwargs:
         pp = BboxPatch(rect, **kwargs)

lib/mpl_toolkits/tests/test_axes_grid1.py

@@ -8,7 +8,7 @@
 from matplotlib.colors import LogNorm
 from matplotlib.transforms import Bbox, TransformedBbox
 from matplotlib.testing.decorators import (
-    image_comparison, remove_ticks_and_titles)
+    check_figures_equal, image_comparison, remove_ticks_and_titles)
 
 from mpl_toolkits.axes_grid1 import (
     axes_size as Size,
@@ -494,3 +494,19 @@ def test_grid_axes_position(direction):
     assert loc[1]._nx > loc[0]._nx and loc[2]._ny < loc[0]._ny
     assert loc[0]._nx == loc[2]._nx and loc[0]._ny == loc[1]._ny
     assert loc[3]._nx == loc[1]._nx and loc[3]._ny == loc[2]._ny
+
+
+@check_figures_equal(extensions=["png"])
+def test_mark_inset_unstales_viewlim(fig_test, fig_ref):
+    inset, full = fig_test.subplots(1, 2)
+    full.plot([0, 5], [0, 5])
+    inset.set(xlim=(1, 2), ylim=(1, 2))
+    # Check that mark_inset unstales full's viewLim before drawing the marks.
+    mark_inset(full, inset, 1, 4)
+
+    inset, full = fig_ref.subplots(1, 2)
+    full.plot([0, 5], [0, 5])
+    inset.set(xlim=(1, 2), ylim=(1, 2))
+    mark_inset(full, inset, 1, 4)
+    # Manually unstale the full's viewLim.
+    fig_ref.canvas.draw()