Fix inversion of 3d axis.

... which was broken because 3d axises stored and accessed their viewlim
info sometimes in xy_viewLim/zz_viewLim and sometimes in v_interval (and
likewise for datalim), leading to out-of-sync info...

Not deprecating d_interval/v_interval for now both because this needs to
go to 3.1.1 to fix the breakage and because I think storing the info in
axis attributes actually makes *more* sense than in viewLim/dataLim --
but fully switching to d_interval/v_interval needs bigger surgery.

lib/matplotlib/axis.py

@@ -1890,6 +1890,36 @@ def get_minpos(self):
         raise NotImplementedError()
 
 
+def _make_getset_interval(method_name, lim_name, attr_name):
+    """
+    Helper to generate ``get_{data,view}_interval`` and
+    ``set_{data,view}_interval`` implementations.
+    """
+
+    def getter(self):
+        # docstring inherited.
+        return getattr(getattr(self.axes, lim_name), attr_name)
+
+    def setter(self, vmin, vmax, ignore=False):
+        # docstring inherited.
+        if ignore:
+            setattr(getattr(self.axes, lim_name), attr_name, (vmin, vmax))
+        else:
+            oldmin, oldmax = getter(self)
+            if oldmin < oldmax:
+                setter(self, min(vmin, vmax, oldmin), max(vmin, vmax, oldmax),
+                       ignore=True)
+            else:
+                setter(self, max(vmin, vmax, oldmax), min(vmin, vmax, oldmin),
+                       ignore=True)
+        self.stale = True
+
+    getter.__name__ = f"get_{method_name}_interval"
+    setter.__name__ = f"set_{method_name}_interval"
+
+    return getter, setter
+
+
 class XAxis(Axis):
     __name__ = 'xaxis'
     axis_name = 'x'
@@ -2133,39 +2163,14 @@ def get_ticks_position(self):
                 "default": "default", "unknown": "unknown"}[
                     self._get_ticks_position()]
 
-    def get_view_interval(self):
-        # docstring inherited
-        return self.axes.viewLim.intervalx
-
-    def set_view_interval(self, vmin, vmax, ignore=False):
-        # docstring inherited
-        if ignore:
-            self.axes.viewLim.intervalx = vmin, vmax
-        else:
-            Vmin, Vmax = self.get_view_interval()
-            if Vmin < Vmax:
-                self.axes.viewLim.intervalx = (min(vmin, vmax, Vmin),
-                                               max(vmin, vmax, Vmax))
-            else:
-                self.axes.viewLim.intervalx = (max(vmin, vmax, Vmin),
-                                               min(vmin, vmax, Vmax))
+    get_view_interval, set_view_interval = _make_getset_interval(
+        "view", "viewLim", "intervalx")
+    get_data_interval, set_data_interval = _make_getset_interval(
+        "data", "dataLim", "intervalx")
 
     def get_minpos(self):
         return self.axes.dataLim.minposx
 
-    def get_data_interval(self):
-        # docstring inherited
-        return self.axes.dataLim.intervalx
-
-    def set_data_interval(self, vmin, vmax, ignore=False):
-        # docstring inherited
-        if ignore:
-            self.axes.dataLim.intervalx = vmin, vmax
-        else:
-            Vmin, Vmax = self.get_data_interval()
-            self.axes.dataLim.intervalx = min(vmin, Vmin), max(vmax, Vmax)
-        self.stale = True
-
     def set_default_intervals(self):
         # docstring inherited
         xmin, xmax = 0., 1.
@@ -2460,40 +2465,14 @@ def get_ticks_position(self):
                 "default": "default", "unknown": "unknown"}[
                     self._get_ticks_position()]
 
-    def get_view_interval(self):
-        # docstring inherited
-        return self.axes.viewLim.intervaly
-
-    def set_view_interval(self, vmin, vmax, ignore=False):
-        # docstring inherited
-        if ignore:
-            self.axes.viewLim.intervaly = vmin, vmax
-        else:
-            Vmin, Vmax = self.get_view_interval()
-            if Vmin < Vmax:
-                self.axes.viewLim.intervaly = (min(vmin, vmax, Vmin),
-                                               max(vmin, vmax, Vmax))
-            else:
-                self.axes.viewLim.intervaly = (max(vmin, vmax, Vmin),
-                                               min(vmin, vmax, Vmax))
-        self.stale = True
+    get_view_interval, set_view_interval = _make_getset_interval(
+        "view", "viewLim", "intervaly")
+    get_data_interval, set_data_interval = _make_getset_interval(
+        "data", "dataLim", "intervaly")
 
     def get_minpos(self):
         return self.axes.dataLim.minposy
 
-    def get_data_interval(self):
-        # docstring inherited
-        return self.axes.dataLim.intervaly
-
-    def set_data_interval(self, vmin, vmax, ignore=False):
-        # docstring inherited
-        if ignore:
-            self.axes.dataLim.intervaly = vmin, vmax
-        else:
-            Vmin, Vmax = self.get_data_interval()
-            self.axes.dataLim.intervaly = min(vmin, Vmin), max(vmax, Vmax)
-        self.stale = True
-
     def set_default_intervals(self):
         # docstring inherited
         ymin, ymax = 0., 1.

lib/mpl_toolkits/mplot3d/axis3d.py

@@ -68,9 +68,6 @@ def __init__(self, adir, v_intervalx, d_intervalx, axes, *args,
                  rotate_label=None, **kwargs):
         # adir identifies which axes this is
         self.adir = adir
-        # data and viewing intervals for this direction
-        self.d_interval = d_intervalx
-        self.v_interval = v_intervalx
 
         # This is a temporary member variable.
         # Do not depend on this existing in future releases!
@@ -105,6 +102,10 @@ def __init__(self, adir, v_intervalx, d_intervalx, axes, *args,
                  })
 
         maxis.XAxis.__init__(self, axes, *args, **kwargs)
+
+        # data and viewing intervals for this direction
+        self.d_interval = d_intervalx
+        self.v_interval = v_intervalx
         self.set_rotate_label(rotate_label)
 
     def init3d(self):
@@ -420,42 +421,49 @@ def draw(self, renderer):
         renderer.close_group('axis3d')
         self.stale = False
 
-    def get_view_interval(self):
-        # docstring inherited
-        return self.v_interval
-
-    def set_view_interval(self, vmin, vmax, ignore=False):
-        # docstring inherited
-        if ignore:
-            self.v_interval = vmin, vmax
-        else:
-            Vmin, Vmax = self.get_view_interval()
-            self.v_interval = min(vmin, Vmin), max(vmax, Vmax)
-
     # TODO: Get this to work properly when mplot3d supports
     #       the transforms framework.
     def get_tightbbox(self, renderer):
         # Currently returns None so that Axis.get_tightbbox
         # doesn't return junk info.
         return None
 
+    @property
+    def d_interval(self):
+        return self.get_data_interval()
+
+    @d_interval.setter
+    def d_interval(self, minmax):
+        return self.set_data_interval(*minmax)
+
+    @property
+    def v_interval(self):
+        return self.get_view_interval()
+
+    @d_interval.setter
+    def v_interval(self, minmax):
+        return self.set_view_interval(*minmax)
+
 
 # Use classes to look at different data limits
 
 
 class XAxis(Axis):
-    def get_data_interval(self):
-        # docstring inherited
-        return self.axes.xy_dataLim.intervalx
+    get_view_interval, set_view_interval = maxis._make_getset_interval(
+        "view", "xy_viewLim", "intervalx")
+    get_data_interval, set_data_interval = maxis._make_getset_interval(
+        "data", "xy_dataLim", "intervalx")
 
 
 class YAxis(Axis):
-    def get_data_interval(self):
-        # docstring inherited
-        return self.axes.xy_dataLim.intervaly
+    get_view_interval, set_view_interval = maxis._make_getset_interval(
+        "view", "xy_viewLim", "intervaly")
+    get_data_interval, set_data_interval = maxis._make_getset_interval(
+        "data", "xy_dataLim", "intervaly")
 
 
 class ZAxis(Axis):
-    def get_data_interval(self):
-        # docstring inherited
-        return self.axes.zz_dataLim.intervalx
+    get_view_interval, set_view_interval = maxis._make_getset_interval(
+        "view", "zz_viewLim", "intervalx")
+    get_data_interval, set_data_interval = maxis._make_getset_interval(
+        "data", "zz_dataLim", "intervalx")

lib/mpl_toolkits/tests/test_mplot3d.py

@@ -801,6 +801,18 @@ def test_line3d_set_get_data_3d():
     np.testing.assert_array_equal((x2, y2, z2), line.get_data_3d())
 
 
+@check_figures_equal(extensions=["png"])
+def test_inverted(fig_test, fig_ref):
+    # Plot then invert.
+    ax = fig_test.add_subplot(projection="3d")
+    ax.plot([1, 1, 10, 10], [1, 10, 10, 10], [1, 1, 1, 10])
+    ax.invert_yaxis()
+    # Invert then plot.
+    ax = fig_ref.add_subplot(projection="3d")
+    ax.invert_yaxis()
+    ax.plot([1, 1, 10, 10], [1, 10, 10, 10], [1, 1, 1, 10])
+
+
 def test_inverted_cla():
     # Github PR #5450. Setting autoscale should reset
     # axes to be non-inverted.