FIX: Updating contour methods to work with norm callbacks

greglucas · greglucas · commit 8eaff42f0ae8 · 2021-02-21T15:15:48.000-07:00
Quadcontourset overrides ScalarMappable's `changed()` function,
which meant that autoscaling would get called with the wrong data
too early. Therefore, we force an autoscale with the proper data
earlier in the `Quadcontourset.changed()` function.
diff --git a/lib/matplotlib/cm.py b/lib/matplotlib/cm.py
@@ -476,8 +476,9 @@ def autoscale_None(self):
         """
         if self._A is None:
             raise TypeError('You must first set_array for mappable')
+        # If the norm updates the limits *self.changed()* will be called
+        # through the callbacks attached to the norm
         self.norm.autoscale_None(self._A)
-        self.changed()
 
     def _add_checker(self, checker):
         """
diff --git a/lib/matplotlib/colorbar.py b/lib/matplotlib/colorbar.py
@@ -1075,7 +1075,7 @@ def _mesh(self):
         # vmax of the colorbar, not the norm.  This allows the situation
         # where the colormap has a narrower range than the colorbar, to
         # accommodate extra contours:
-        norm = copy.copy(self.norm)
+        norm = copy.deepcopy(self.norm)
         norm.vmin = self.vmin
         norm.vmax = self.vmax
         x = np.array([0.0, 1.0])
diff --git a/lib/matplotlib/contour.py b/lib/matplotlib/contour.py
@@ -1027,6 +1027,11 @@ def _make_paths(self, segs, kinds):
             return [mpath.Path(seg) for seg in segs]
 
     def changed(self):
+        # Force an autoscale immediately because self.to_rgba() calls
+        # autoscale_None() internally with the data passed to it,
+        # so if vmin/vmax are not set yet, this would override them with
+        # content from *cvalues* rather than levels like we want
+        self.norm.autoscale_None(self.levels)
         tcolors = [(tuple(rgba),)
                    for rgba in self.to_rgba(self.cvalues, alpha=self.alpha)]
         self.tcolors = tcolors
