Simplify function to change axis

Previous proposal was over-engineered with the idea of
possibly extending the number of scales the axis could scale to.
Since we're likely to just stick to linear and log, the
function is now easier to understand and maintain.

qt/applications/workbench/workbench/plotting/figureinteraction.py

@@ -57,8 +57,6 @@
         ("Log x/Lin y", ("log", "linear")),
     ]
 )
-# Options to quickly switch axes scales with key shortcuts
-AXES_SCALE_DEFAULT_SWITCH = ["linear", "log"]
 COLORBAR_SCALE_MENU_OPTS = OrderedDict([("Linear", Normalize), ("Log", LogNorm)])
 
 
@@ -148,7 +146,6 @@ def on_scroll(self, event):
         event.canvas.draw()
 
     def on_key_press(self, event):
-
         ax = event.inaxes
         if ax is None or isinstance(ax, Axes3D) or len(ax.get_images()) == 0 and len(ax.get_lines()) == 0:
             return
@@ -164,10 +161,9 @@ def on_key_press(self, event):
             self._quick_change_axes((ax.get_xscale(), next_yscale), ax)
 
     def _get_next_axis_scale(self, current_scale):
-        available_scales = AXES_SCALE_DEFAULT_SWITCH
-        scale_index = available_scales.index(current_scale) if current_scale in available_scales else 0
-        next_scale = available_scales[(scale_index + 1) % len(available_scales)]
-        return next_scale
+        if current_scale == "linear":
+            return "log"
+        return "linear"
 
     def on_mouse_button_press(self, event):
         """Respond to a MouseEvent where a button was pressed"""