Accommodate upcoming changes to RectangleSelector API

skimage/viewer/canvastools/recttool.py

@@ -41,15 +41,16 @@ class RectangleTool(CanvasToolBase, RectangleSelector):
 
     def __init__(self, viewer, on_move=None, on_release=None, on_enter=None,
                  maxdist=10, rect_props=None):
-        CanvasToolBase.__init__(self, viewer, on_move=on_move,
-                                on_enter=on_enter, on_release=on_release)
-
+        self._rect = None
         props = dict(edgecolor=None, facecolor='r', alpha=0.15)
         props.update(rect_props if rect_props is not None else {})
         if props['edgecolor'] is None:
             props['edgecolor'] = props['facecolor']
-        RectangleSelector.__init__(self, self.ax, lambda *args: None,
+        RectangleSelector.__init__(self, viewer.ax, lambda *args: None,
                                    rectprops=props)
+        CanvasToolBase.__init__(self, viewer, on_move=on_move,
+                                on_enter=on_enter, on_release=on_release)
+
         # Events are handled by the viewer
         try:
             self.disconnect_events()
@@ -87,6 +88,8 @@ class RectangleTool(CanvasToolBase, RectangleSelector):
 
     @property
     def _rect_bbox(self):
+        if not self._rect:
+            return 0, 0, 0, 0
         x0 = self._rect.get_x()
         y0 = self._rect.get_y()
         width = self._rect.get_width()
@@ -142,7 +145,10 @@ class RectangleTool(CanvasToolBase, RectangleSelector):
         if not self.ax.in_axes(event):
             self.eventpress = None
             return
-        RectangleSelector.release(self, event)
+        if hasattr(RectangleSelector, '_release'):
+            RectangleSelector._release(self, event)
+        else:
+            RectangleSelector.release(self, event)
         self._extents_on_press = None
         # Undo hiding of rectangle and redraw.
         self.set_visible(True)
@@ -158,7 +164,10 @@ class RectangleTool(CanvasToolBase, RectangleSelector):
             self.set_visible(False)
             self.redraw()
         self.set_visible(True)
-        RectangleSelector.press(self, event)
+        if hasattr(RectangleSelector, '_press'):
+            RectangleSelector._press(self, event)
+        else:
+            RectangleSelector.press(self, event)
 
     def _set_active_handle(self, event):
         """Set active handle based on the location of the mouse event"""