Implemented single_axis option as described in documentation.

chaco/tools/drag_zoom.py

@@ -81,7 +81,7 @@ def dragging(self, event):
         # Compute the zoom amount based on the pixel difference between
         # the previous mouse event and the current one.
 
-        if self.maintain_aspect_ratio:
+        if self.maintain_aspect_ratio or self.single_axis:
             zoom_x = zoom_y = self._calc_zoom(self._prev_y, event.y)
         else:
             zoom_x = self._calc_zoom(self._prev_x, event.x)
@@ -91,8 +91,22 @@ def dragging(self, event):
         zoom_x = 1.0/zoom_x
         zoom_y = 1.0/zoom_y
 
-        self.zoom_in_x(zoom_x)
-        self.zoom_in_y(zoom_y)
+        if not self.single_axis:
+            self.zoom_in_x(zoom_x)
+            self.zoom_in_y(zoom_y)
+        else: 
+            # Zoom only along specified axis
+            flip = self.component.orientation=='v'
+            if self.axis == 'index':
+                if flip:
+                    self.zoom_in_y(zoom_y)
+                else:
+                    self.zoom_in_x(zoom_x)
+            if self.axis == 'value':
+                if flip:
+                    self.zoom_in_x(zoom_x)
+                else:
+                    self.zoom_in_y(zoom_y)
 
         return
 

chaco/tools/range_selection.py

@@ -613,6 +613,10 @@ def _set_selection(self, val):
                 new_mask = (data_pts >= low) & (data_pts <= high)
                 selection_masks.append(new_mask)
                 self._selection_mask = new_mask
+            else:
+                # Reset datasource metadata if no points selected
+                del datasource.metadata[self.mask_metadata_name]
+
             datasource.metadata_changed = {self.mask_metadata_name: val}
 
         self.trait_property_changed("selection", oldval, val)