Test scroll zoom bbox update

Author: oscargus

lib/matplotlib/tests/test_axes.py

@@ -7118,6 +7118,42 @@ def test_spines_properbbox_after_zoom():
     np.testing.assert_allclose(bb.get_points(), bb2.get_points(), rtol=1e-6)
 
 
+def test_limits_after_scroll_zoom():
+    fig, ax = plt.subplots()
+    #
+    xlim = (-0.5, 0.5)
+    ylim = (-1, 2)
+    ax.set_xlim(xlim)
+    ax.set_ylim(ymin=ylim[0], ymax=ylim[1])
+    # This is what scroll zoom calls:
+    # Zoom with factor 1, small numerical change
+    ax._set_view_from_bbox((200, 200, 1.))
+    np.testing.assert_allclose(xlim, ax.get_xlim(), atol=1e-16)
+    np.testing.assert_allclose(ylim, ax.get_ylim(), atol=1e-16)
+
+    # Zoom in
+    ax._set_view_from_bbox((200, 200, 2.))
+    # Hard-coded values
+    new_xlim = (-0.3790322580645161, 0.12096774193548387)
+    new_ylim = (-0.40625, 1.09375)
+
+    res_xlim = ax.get_xlim()
+    res_ylim = ax.get_ylim()
+    np.testing.assert_allclose(res_xlim[1] - res_xlim[0], 0.5)
+    np.testing.assert_allclose(res_ylim[1] - res_ylim[0], 1.5)
+    np.testing.assert_allclose(new_xlim, res_xlim, atol=1e-16)
+    np.testing.assert_allclose(new_ylim, res_ylim)
+
+    # Zoom out, should be same as before, except for numerical issues
+    ax._set_view_from_bbox((200, 200, 0.5))
+    res_xlim = ax.get_xlim()
+    res_ylim = ax.get_ylim()
+    np.testing.assert_allclose(res_xlim[1] - res_xlim[0], 1)
+    np.testing.assert_allclose(res_ylim[1] - res_ylim[0], 3)
+    np.testing.assert_allclose(xlim, res_xlim, atol=1e-16)
+    np.testing.assert_allclose(ylim, res_ylim, atol=1e-16)
+
+
 def test_gettightbbox_ignore_nan():
     fig, ax = plt.subplots()
     remove_ticks_and_titles(fig)