The views positions mixin automatically adds the clear as axobserver

Author: fariza

examples/user_interfaces/navigation.py

@@ -1,6 +1,6 @@
 import matplotlib
-matplotlib.use('GTK3Cairo')
-# matplotlib.use('TkAGG')
+# matplotlib.use('GTK3Cairo')
+matplotlib.use('TkAGG')
 matplotlib.rcParams['toolbar'] = 'navigation'
 import matplotlib.pyplot as plt
 from matplotlib.backend_tools import ToolBase
@@ -54,6 +54,6 @@ def trigger(self, event):
     fig.canvas.manager.navigation.add_tool('copy', CopyToolGTK3)
 
 # Just for fun, lets remove the back button
-fig.canvas.manager.navigation.remove_tool('Back')
+# fig.canvas.manager.navigation.remove_tool('Back')
 
 plt.show()

lib/matplotlib/backend_tools.py

@@ -97,9 +97,9 @@ def set_figure(self, figure):
 
 
 class ToolPersistentBase(ToolBase):
-    """Persisten tool
+    """Persistent tool
 
-    Persistent Tools are keept alive after their initialization,
+    Persistent Tools are kept alive after their initialization,
     a reference of the instance is kept by `navigation`.
 
     Notes
@@ -287,20 +287,41 @@ def trigger(self, event):
 
 
 class ViewsPositionsMixin(object):
+    """Mixin to handle changes in views and positions
+
+    Tools that change the views and positions, use this mixin to
+    keep track of the changes.
+    """
+
     views = WeakKeyDictionary()
+    """Record of views with Figure objects as keys"""
+
     positions = WeakKeyDictionary()
+    """Record of positions with Figure objects as keys"""
 
     def init_vp(self):
+        """Add a figure to the list of figures handled by this mixin
+
+        To handle the views and positions for a given figure, this method
+        has to be called at least once before any other method.
+
+        The best way to call it is during the set_figure method of the tools
+        """
         if self.figure not in self.views:
             self.views[self.figure] = cbook.Stack()
             self.positions[self.figure] = cbook.Stack()
             # Define Home
             self.push_current()
+            # Adding the clear method as axobserver, removes this burden from
+            # the backend
+            self.figure.add_axobserver(self.clear)
 
     @classmethod
     def clear(cls, figure):
         """Reset the axes stack"""
+        print('clear')
         if figure in cls.views:
+            print('done clear')
             cls.views[figure].clear()
             cls.positions[figure].clear()
 
@@ -375,12 +396,9 @@ def forward(self):
         self.positions[self.figure].forward()
 
 
-def clear_views_positions(figure):
-    ViewsPositionsMixin.clear(figure)
-
-
 class ViewsPositionsBase(ViewsPositionsMixin, ToolBase):
     # Simple base to avoid repeating code on Home, Back and Forward
+    # Not of much use for other tools, so not documented
     _on_trigger = None
 
     def set_figure(self, *args):
@@ -435,6 +453,8 @@ class SaveFigureBase(ToolBase):
 
 
 class ZoomPanBase(ViewsPositionsMixin, ToolToggleBase):
+    # Base class to group common functionality between zoom and pan
+    # Not of much use for other tools, so not documented
     def __init__(self, *args):
         ToolToggleBase.__init__(self, *args)
         self.init_vp()

lib/matplotlib/backends/backend_gtk3.py

@@ -31,8 +31,7 @@ def fn_name(): return sys._getframe(1).f_code.co_name
 from matplotlib.backend_bases import RendererBase, GraphicsContextBase, \
      FigureManagerBase, FigureCanvasBase, NavigationToolbar2, cursors, TimerBase
 from matplotlib.backend_bases import ShowBase, ToolbarBase, NavigationBase
-from matplotlib.backend_tools import SaveFigureBase, ConfigureSubplotsBase, \
-    clear_views_positions
+from matplotlib.backend_tools import SaveFigureBase, ConfigureSubplotsBase
 
 from matplotlib.cbook import is_string_like, is_writable_file_like
 from matplotlib.colors import colorConverter
@@ -442,7 +441,7 @@ def destroy(*args):
         def notify_axes_change(fig):
             'this will be called whenever the current axes is changed'
             if self.navigation is not None:
-                clear_views_positions(fig)
+                pass
             elif self.toolbar is not None: self.toolbar.update()
         self.canvas.figure.add_axobserver(notify_axes_change)
 

lib/matplotlib/backends/backend_tkagg.py

@@ -21,8 +21,7 @@
 from matplotlib.backend_bases import FigureManagerBase, FigureCanvasBase
 from matplotlib.backend_bases import NavigationToolbar2, cursors, TimerBase
 from matplotlib.backend_bases import ShowBase, ToolbarBase, NavigationBase
-from matplotlib.backend_tools import SaveFigureBase, ConfigureSubplotsBase, \
-    clear_views_positions
+from matplotlib.backend_tools import SaveFigureBase, ConfigureSubplotsBase
 from matplotlib._pylab_helpers import Gcf
 
 from matplotlib.figure import Figure
@@ -544,7 +543,7 @@ def __init__(self, canvas, num, window):
         def notify_axes_change(fig):
             'this will be called whenever the current axes is changed'
             if self.navigation is not None:
-                clear_views_positions(fig)
+                pass
             elif self.toolbar is not None:
                 self.toolbar.update()
         self.canvas.figure.add_axobserver(notify_axes_change)