ENH: Adding zoom and pan to colorbar

greglucas · greglucas · commit 1e7822091e5b · 2021-09-20T06:51:03.000-06:00
The zoom and pan funcitons change the vmin/vmax of the norm
attached to the colorbar. The colorbar is rendered as an inset
axis, but the event handler is implemented on the parent axis.
diff --git a/doc/api/next_api_changes/behavior/19515-GL.rst b/doc/api/next_api_changes/behavior/19515-GL.rst
@@ -0,0 +1,6 @@
+Colorbars now have pan and zoom functionality
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Interactive plots with colorbars can now be zoomed and panned on
+the colorbar axis. This adjusts the *vmin* and *vmax* of the
+``ScalarMappable`` associated with the colorbar.
diff --git a/lib/matplotlib/colorbar.py b/lib/matplotlib/colorbar.py
@@ -1274,6 +1274,36 @@ def _short_axis(self):
             return self.ax.xaxis
         return self.ax.yaxis
 
+    def _get_view(self):
+        # docstring inherited
+        # An interactive view for a colorbar is the norm's vmin/vmax
+        return self.norm.vmin, self.norm.vmax
+
+    def _set_view(self, view):
+        # docstring inherited
+        # An interactive view for a colorbar is the norm's vmin/vmax
+        self.norm.vmin, self.norm.vmax = view
+
+    def _set_view_from_bbox(self, bbox, direction='in',
+                            mode=None, twinx=False, twiny=False):
+        # docstring inherited
+        # For colorbars, we use the zoom bbox to scale the norm's vmin/vmax
+        new_xbound, new_ybound = self.ax._prepare_view_from_bbox(
+            bbox, direction=direction, mode=mode, twinx=twinx, twiny=twiny)
+        if self.orientation == 'horizontal':
+            self.norm.vmin, self.norm.vmax = new_xbound
+        elif self.orientation == 'vertical':
+            self.norm.vmin, self.norm.vmax = new_ybound
+
+    def drag_pan(self, button, key, x, y):
+        # docstring inherited
+        points = self.ax._get_pan_points(button, key, x, y)
+        if points is not None:
+            if self.orientation == 'horizontal':
+                self.norm.vmin, self.norm.vmax = points[:, 0]
+            elif self.orientation == 'vertical':
+                self.norm.vmin, self.norm.vmax = points[:, 1]
+
 
 ColorbarBase = Colorbar  # Backcompat API
 
