content: # -*- coding: utf-8 -*-
  # Copyright 2007-2016 The HyperSpy developers
  #
  # This file is part of  HyperSpy.
  #
  #  HyperSpy is free software: you can redistribute it and/or modify
  # it under the terms of the GNU General Public License as published by
  # the Free Software Foundation, either version 3 of the License, or
  # (at your option) any later version.
  #
  #  HyperSpy is distributed in the hope that it will be useful,
  # but WITHOUT ANY WARRANTY; without even the implied warranty of
  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  # GNU General Public License for more details.
  #
  # You should have received a copy of the GNU General Public License
  # along with  HyperSpy.  If not, see <http://www.gnu.org/licenses/>.
  
  from __future__ import division
  
  import matplotlib.pyplot as plt
  from matplotlib.backend_bases import MouseEvent
  import numpy as np
  
  from hyperspy.drawing.utils import on_figure_window_close
  from hyperspy.events import Events, Event
  
  
  class WidgetBase(object):
  
      """Base class for interactive widgets/patches. A widget creates and
      maintains one or more matplotlib patches, and manages the interaction code
      so that the user can maniuplate it on the fly.
  
      This base class implements functionality witch is common to all such
      widgets, mainly the code that manages the patch, axes management, and
      sets up common events ('changed' and 'closed').
  
      Any inherting subclasses must implement the following methods:
          _set_patch(self)
          _on_navigate(obj, name, old, new)  # Only for widgets that can navigate
  
      It should also make sure to fill the 'axes' attribute as early as
      possible (but after the base class init), so that it is available when
      needed.
      """
  
      def __init__(self, axes_manager=None, **kwargs):
          self.axes_manager = axes_manager
          self._axes = list()
          self.ax = None
          self.picked = False
          self.selected = False
          self._selected_artist = None
          self._size = 1.
          self.color = 'red'
          self.__is_on = True
          self.background = None
          self.patch = []
          self.cids = list()
          self.blit = True
          self.events = Events()
          self.events.changed = Event(doc="""
              Event that triggers when the widget has a significant change.
  
              The event triggers after the internal state of the widget has been
              updated.
  
              Arguments:
              ----------
                  widget:
                      The widget that changed
              """, arguments=['obj'])
          self.events.closed = Event(doc="""
              Event that triggers when the widget closed.
  
              The event triggers after the widget has already been closed.
  
              Arguments:
              ----------
                  widget:
                      The widget that closed
              """, arguments=['obj'])
          self._navigating = False
          super(WidgetBase, self).__init__(**kwargs)
  
      def _get_axes(self):
          return self._axes
  
      def _set_axes(self, axes):
          if axes is None:
              self._axes = list()
          else:
              self._axes = axes
  
      axes = property(lambda s: s._get_axes(),
                      lambda s, v: s._set_axes(v))
  
      def is_on(self):
          """Determines if the widget is set to draw if valid (turned on).
          """
          return self.__is_on
  
      def set_on(self, value):
          """Change the on state of the widget. If turning off, all patches will
          be removed from the matplotlib axes and the widget will disconnect from
          all events. If turning on, the patch(es) will be added to the
          matplotlib axes, and the widget will connect to its default events.
          """
          did_something = False
          if value is not self.is_on() and self.ax is not None:
              did_something = True
              if value is True:
                  self._add_patch_to(self.ax)
                  self.connect(self.ax)
              elif value is False:
                  for container in [
                          self.ax.patches,
                          self.ax.lines,
                          self.ax.artists,
                          self.ax.texts]:
                      for p in self.patch:
                          if p in container:
                              container.remove(p)
                  self.disconnect()
          if hasattr(super(WidgetBase, self), 'set_on'):
              super(WidgetBase, self).set_on(value)
          if did_something:
              self.draw_patch()
              if value is False:
                  self.ax = None
          self.__is_on = value
  
      def _set_patch(self):
          """Create the matplotlib patch(es), and store it in self.patch
          """
          if hasattr(super(WidgetBase, self), '_set_patch'):
              super(WidgetBase, self)._set_patch()
          # Must be provided by the subclass
  
      def _add_patch_to(self, ax):
          """Create and add the matplotlib patches to 'ax'
          """
          self._set_patch()
          for p in self.patch:
              ax.add_artist(p)
              p.set_animated(hasattr(ax, 'hspy_fig'))
          if hasattr(super(WidgetBase, self), '_add_patch_to'):
              super(WidgetBase, self)._add_patch_to(ax)
  
      def set_mpl_ax(self, ax):
          """Set the matplotlib Axes that the widget will draw to. If the widget
          on state is True, it will also add the patch to the Axes, and connect
          to its default events.
          """
          if ax is self.ax:
              return  # Do nothing
          # Disconnect from previous axes if set
          if self.ax is not None and self.is_on():
              self.disconnect()
          self.ax = ax
          canvas = ax.figure.canvas
          if self.is_on() is True:
              self._add_patch_to(ax)
              self.connect(ax)
              canvas.draw()
              self.select()
  
      def select(self):
          """
          Cause this widget to be the selected widget in its MPL axes. This
          assumes that the widget has its patch added to the MPL axes.
          """
          if not self.patch or not self.is_on() or not self.ax:
              return
  
          canvas = self.ax.figure.canvas
          # Simulate a pick event
          x, y = self.patch[0].get_transform().transform_point((0, 0))
          mouseevent = MouseEvent('pick_event', canvas, x, y)
          canvas.pick_event(mouseevent, self.patch[0])
          self.picked = False
  
      def connect(self, ax):
          """Connect to the matplotlib Axes' events.
          """
          on_figure_window_close(ax.figure, self.close)
          if self._navigating:
              self.connect_navigate()
  
      def connect_navigate(self):
          """Connect to the axes_manager such that changes in the widget or in
          the axes_manager are reflected in the other.
          """
          if self._navigating:
              self.disconnect_navigate()
          self.axes_manager.events.indices_changed.connect(
              self._on_navigate, {'obj': 'axes_manager'})
          self._on_navigate(self.axes_manager)    # Update our position
          self._navigating = True
  
      def disconnect_navigate(self):
          """Disconnect a previous naivgation connection.
          """
          self.axes_manager.events.indices_changed.disconnect(self._on_navigate)
          self._navigating = False
  
      def _on_navigate(self, axes_manager):
          """Callback for axes_manager's change notification.
          """
          pass    # Implement in subclass!
  
      def disconnect(self):
          """Disconnect from all events (both matplotlib and navigation).
          """
          for cid in self.cids:
              try:
                  self.ax.figure.canvas.mpl_disconnect(cid)
              except:
                  pass
          if self._navigating:
              self.disconnect_navigate()
  
      def close(self, window=None):
          """Set the on state to off (removes patch and disconnects), and trigger
          events.closed.
          """
          self.set_on(False)
          self.events.closed.trigger(obj=self)
  
      def draw_patch(self, *args):
          """Update the patch drawing.
          """
          try:
              if hasattr(self.ax, 'hspy_fig'):
                  self.ax.hspy_fig._draw_animated()
              elif self.ax.figure is not None:
                  self.ax.figure.canvas.draw_idle()
          except AttributeError:
              pass  # When figure is None, typically when closing
  
      def _v2i(self, axis, v):
          """Wrapped version of DataAxis.value2index, which bounds the index
          inbetween axis.low_index and axis.high_index+1, and does not raise a
          ValueError.
          """
          try:
              return axis.value2index(v)
          except ValueError:
              if v > axis.high_value:
                  return axis.high_index + 1
              elif v < axis.low_value:
                  return axis.low_index
              else:
                  raise
  
      def _i2v(self, axis, i):
          """Wrapped version of DataAxis.index2value, which bounds the value
          inbetween axis.low_value and axis.high_value+axis.scale, and does not
          raise a ValueError.
          """
          try:
              return axis.index2value(i)
          except ValueError:
              if i > axis.high_index:
                  return axis.high_value + axis.scale
              elif i < axis.low_index:
                  return axis.low_value
              else:
                  raise
  
  
  class DraggableWidgetBase(WidgetBase):
  
      """Adds the `position` and `indices` properties, and adds a framework for
      letting the user drag the patch around. Also adds the `moved` event.
  
      The default behavior is that `position` snaps to the values corresponding
      to the values of the axes grid (i.e. no subpixel values). This behavior
      can be controlled by the property `snap_position`.
  
      Any inheritors must override these methods:
          _onmousemove(self, event)
          _update_patch_position(self)
          _set_patch(self)
      """
  
      def __init__(self, axes_manager, **kwargs):
          super(DraggableWidgetBase, self).__init__(axes_manager, **kwargs)
          self.events.moved = Event(doc="""
              Event that triggers when the widget was moved.
  
              The event triggers after the internal state of the widget has been
              updated. This event does not differentiate on how the position of
              the widget was changed, so it is the responsibility of the user
              to suppress events as neccessary to avoid closed loops etc.
  
              Arguments:
              ----------
                  obj:
                      The widget that was moved.
              """, arguments=['obj'])
          self._snap_position = True
  
          # Set default axes
          if self.axes_manager is not None:
              if self.axes_manager.navigation_dimension > 0:
                  self.axes = self.axes_manager.navigation_axes[0:1]
              else:
                  self.axes = self.axes_manager.signal_axes[0:1]
          else:
              self._pos = np.array([0.])
  
      def _set_axes(self, axes):
          super(DraggableWidgetBase, self)._set_axes(axes)
          if self.axes:
              self._pos = np.array([ax.low_value for ax in self.axes])
  
      def _get_indices(self):
          """Returns a tuple with the position (indices).
          """
          idx = []
          for i in range(len(self.axes)):
              idx.append(self.axes[i].value2index(self._pos[i]))
          return tuple(idx)
  
      def _set_indices(self, value):
          """Sets the position of the widget (by indices). The dimensions should
          correspond to that of the 'axes' attribute. Calls _pos_changed if the
          value has changed, which is then responsible for triggering any
          relevant events.
          """
          if np.ndim(value) == 0 and len(self.axes) == 1:
              self.position = [self.axes[0].index2value(value)]
          elif len(self.axes) != len(value):
              raise ValueError()
          else:
              p = []
              for i in range(len(self.axes)):
                  p.append(self.axes[i].index2value(value[i]))
              self.position = p
  
      indices = property(lambda s: s._get_indices(),
                         lambda s, v: s._set_indices(v))
  
      def _pos_changed(self):
          """Call when the position of the widget has changed. It triggers the
          relevant events, and updates the patch position.
          """
          if self._navigating:
              with self.axes_manager.events.indices_changed.suppress_callback(
                      self._on_navigate):
                  for i in range(len(self.axes)):
                      self.axes[i].value = self._pos[i]
          self.events.moved.trigger(self)
          self.events.changed.trigger(self)
          self._update_patch_position()
  
      def _validate_pos(self, pos):
          """Validates the passed position. Depending on the position and the
          implementation, this can either fire a ValueError, or return a modified
          position that has valid values. Or simply return the unmodified
          position if everything is ok.
  
          This default implementation bounds the position within the axes limits.
          """
          if len(pos) != len(self.axes):
              raise ValueError()
          pos = np.maximum(pos, [ax.low_value for ax in self.axes])
          pos = np.minimum(pos, [ax.high_value for ax in self.axes])
          if self.snap_position:
              pos = self._do_snap_position(pos)
          return pos
  
      def _get_position(self):
          """Providies the position of the widget (by values) in a tuple.
          """
          return tuple(
              self._pos.tolist())  # Don't pass reference, and make it clear
  
      def _set_position(self, position):
          """Sets the position of the widget (by values). The dimensions should
          correspond to that of the 'axes' attribute. Calls _pos_changed if the
          value has changed, which is then responsible for triggering any
          relevant events.
          """
          position = self._validate_pos(position)
          if np.any(self._pos != position):
              self._pos = np.array(position)
              self._pos_changed()
  
      position = property(lambda s: s._get_position(),
                          lambda s, v: s._set_position(v))
  
      def _do_snap_position(self, value=None):
          """Snaps position to axes grid. Returns snapped value. If value is
          passed as an argument, the internal state is left untouched, if not
          the position attribute is updated to the snapped value.
          """
          value = np.array(value) if value is not None else self._pos
          for i, ax in enumerate(self.axes):
              value[i] = ax.index2value(ax.value2index(value[i]))
          return value
  
      def _set_snap_position(self, value):
          self._snap_position = value
          if value:
              snap_value = self._do_snap_position(self._pos)
              if np.any(self._pos != snap_value):
                  self._pos = snap_value
                  self._pos_changed()
  
      snap_position = property(lambda s: s._snap_position,
                               lambda s, v: s._set_snap_position(v))
  
      def connect(self, ax):
          super(DraggableWidgetBase, self).connect(ax)
          canvas = ax.figure.canvas
          self.cids.append(
              canvas.mpl_connect('motion_notify_event', self._onmousemove))
          self.cids.append(canvas.mpl_connect('pick_event', self.onpick))
          self.cids.append(canvas.mpl_connect(
              'button_release_event', self.button_release))
  
      def _on_navigate(self, axes_manager):
          if axes_manager is self.axes_manager:
              p = self._pos.tolist()
              for i, a in enumerate(self.axes):
                  p[i] = a.value
              self.position = p    # Use property to trigger events
  
      def onpick(self, event):
          # Callback for MPL pick event
          self.picked = (event.artist in self.patch)
          self._selected_artist = event.artist
          if hasattr(super(DraggableWidgetBase, self), 'onpick'):
              super(DraggableWidgetBase, self).onpick(event)
          self.selected = self.picked
  
      def _onmousemove(self, event):
          """Callback for mouse movement. For dragging, the implementor would
          normally check that the widget is picked, and that the event.inaxes
          Axes equals self.ax.
          """
          # This method must be provided by the subclass
          pass
  
      def _update_patch_position(self):
          """Updates the position of the patch on the plot.
          """
          # This method must be provided by the subclass
          pass
  
      def _update_patch_geometry(self):
          """Updates all geometry of the patch on the plot.
          """
          self._update_patch_position()
  
      def button_release(self, event):
          """whenever a mouse button is released"""
          if event.button != 1:
              return
          if self.picked is True:
              self.picked = False
  
  
  class Widget1DBase(DraggableWidgetBase):
  
      """A base class for 1D widgets.
  
      It sets the right dimensions for size and
      position, adds the 'border_thickness' attribute and initalizes the 'axes'
      attribute to the first two navigation axes if possible, if not, the two
      first signal_axes are used. Other than that it mainly supplies common
      utility functions for inheritors, and implements required functions for
      ResizableDraggableWidgetBase.
  
      The implementation for ResizableDraggableWidgetBase methods all assume that
      a Rectangle patch will be used, centered on position. If not, the
      inheriting class will have to override those as applicable.
      """
  
      def _set_position(self, position):
          try:
              len(position)
          except TypeError:
              position = (position,)
          super(Widget1DBase, self)._set_position(position)
  
      def _validate_pos(self, pos):
          pos = np.maximum(pos, self.axes[0].low_value)
          pos = np.minimum(pos, self.axes[0].high_value)
          return super(Widget1DBase, self)._validate_pos(pos)
  
  
  class ResizableDraggableWidgetBase(DraggableWidgetBase):
  
      """Adds the `size` property and get_size_in_axes method, and adds a
      framework for letting the user resize the patch, including resizing by
      key strokes ('+', '-'). Also adds the 'resized' event.
  
      Utility functions for resizing are implemented by `increase_size` and
      `decrease_size`, which will in-/decrement the size by 1. Other utility
      functions include `get_centre` and `get_centre_indices` which returns the
      center position, and the internal _apply_changes which helps make sure that
      only one 'changed' event is fired for a combined move and resize.
  
      Any inheritors must override these methods:
          _update_patch_position(self)
          _update_patch_size(self)
          _update_patch_geometry(self)
          _set_patch(self)
      """
  
      def __init__(self, axes_manager, **kwargs):
          super(ResizableDraggableWidgetBase, self).__init__(
              axes_manager, **kwargs)
          if not self.axes:
              self._size = np.array([1])
          self.size_step = 1      # = one step in index space
          self._snap_size = True
          self.events.resized = Event(doc="""
              Event that triggers when the widget was resized.
  
              The event triggers after the internal state of the widget has been
              updated. This event does not differentiate on how the size of
              the widget was changed, so it is the responsibility of the user
              to suppress events as neccessary to avoid closed loops etc.
  
              Arguments:
              ----------
                  obj:
                      The widget that was resized.
              """, arguments=['obj'])
          self.no_events_while_dragging = False
          self._drag_store = None
  
      def _set_axes(self, axes):
          super(ResizableDraggableWidgetBase, self)._set_axes(axes)
          if self.axes:
              self._size = np.array([ax.scale for ax in self.axes])
  
      def _get_size(self):
          """Getter for 'size' property. Returns the size as a tuple (to prevent
          unintended in-place changes).
          """
          return tuple(self._size.tolist())
  
      def _set_size(self, value):
          """Setter for the 'size' property. Calls _size_changed to handle size
          change, if the value has changed.
          """
          value = np.minimum(value, [ax.size * ax.scale for ax in self.axes])
          value = np.maximum(value,
                             self.size_step * [ax.scale for ax in self.axes])
          if self.snap_size:
              value = self._do_snap_size(value)
          if np.any(self._size != value):
              self._size = value
              self._size_changed()
  
      size = property(lambda s: s._get_size(), lambda s, v: s._set_size(v))
  
      def _do_snap_size(self, value=None):
          value = np.array(value) if value is not None else self._size
          for i, ax in enumerate(self.axes):
              value[i] = round(value[i] / ax.scale) * ax.scale
          return value
  
      def _set_snap_size(self, value):
          self._snap_size = value
          if value:
              snap_value = self._do_snap_size(self._size)
              if np.any(self._size != snap_value):
                  self._size = snap_value
                  self._size_changed()
  
      snap_size = property(lambda s: s._snap_size,
                           lambda s, v: s._set_snap_size(v))
  
      def _set_snap_all(self, value):
          # Snap position first, as snapped size can depend on position.
          self.snap_position = value
          self.snap_size = value
  
      snap_all = property(lambda s: s.snap_size and s.snap_position,
                          lambda s, v: s._set_snap_all(v))
  
      def increase_size(self):
          """Increment all sizes by 1. Applied via 'size' property.
          """
          self.size = np.array(self.size) + \
              self.size_step * np.array([a.scale for a in self.axes])
  
      def decrease_size(self):
          """Decrement all sizes by 1. Applied via 'size' property.
          """
          self.size = np.array(self.size) - \
              self.size_step * np.array([a.scale for a in self.axes])
  
      def _size_changed(self):
          """Triggers resize and changed events, and updates the patch.
          """
          self.events.resized.trigger(self)
          self.events.changed.trigger(self)
          self._update_patch_size()
  
      def get_size_in_indices(self):
          """Gets the size property converted to the index space (via 'axes'
          attribute).
          """
          s = list()
          for i in range(len(self.axes)):
              s.append(int(round(self._size[i] / self.axes[i].scale)))
          return np.array(s)
  
      def set_size_in_indices(self, value):
          """Sets the size property converted to the index space (via 'axes'
          attribute).
          """
          s = list()
          for i in range(len(self.axes)):
              s.append(int(round(value[i] * self.axes[i].scale)))
          self.size = s   # Use property to get full processing
  
      def get_centre(self):
          """Get's the center indices. The default implementation is simply the
          position + half the size in axes space, which should work for any
          symmetric widget, but more advanced widgets will need to decide whether
          to return the center of gravity or the geometrical center of the
          bounds.
          """
          return self._pos + self._size() / 2.0
  
      def get_centre_index(self):
          """Get's the center position (in index space). The default
          implementation is simply the indices + half the size, which should
          work for any symmetric widget, but more advanced widgets will need to
          decide whether to return the center of gravity or the geometrical
          center of the bounds.
          """
          return self.indices + self.get_size_in_indices() / 2.0
  
      def _update_patch_size(self):
          """Updates the size of the patch on the plot.
          """
          # This method must be provided by the subclass
          pass
  
      def _update_patch_geometry(self):
          """Updates all geometry of the patch on the plot.
          """
          # This method must be provided by the subclass
          pass
  
      def on_key_press(self, event):
          if event.key == "+":
              self.increase_size()
          if event.key == "-":
              self.decrease_size()
  
      def connect(self, ax):
          super(ResizableDraggableWidgetBase, self).connect(ax)
          canvas = ax.figure.canvas
          self.cids.append(canvas.mpl_connect('key_press_event',
                                              self.on_key_press))
  
      def onpick(self, event):
          if hasattr(super(ResizableDraggableWidgetBase, self), 'onpick'):
              super(ResizableDraggableWidgetBase, self).onpick(event)
          if self.picked:
              self._drag_store = (self.position, self.size)
  
      def _apply_changes(self, old_size, old_position):
          """Evalutes whether the widget has been moved/resized, and triggers
          the correct events and updates the patch geometry. This function has
          the advantage that the geometry is updated only once, preventing
          flickering, and the 'changed' event only fires once.
          """
          moved = self.position != old_position
          resized = self.size != old_size
          if moved:
              if self._navigating:
                  e = self.axes_manager.events.indices_changed
                  with e.suppress_callback(self._on_navigate):
                      for i in range(len(self.axes)):
                          self.axes[i].index = self.indices[i]
          if moved or resized:
              # Update patch first
              if moved and resized:
                  self._update_patch_geometry()
              elif moved:
                  self._update_patch_position()
              else:
                  self._update_patch_size()
              # Then fire events
              if not self.no_events_while_dragging or not self.picked:
                  if moved:
                      self.events.moved.trigger(self)
                  if resized:
                      self.events.resized.trigger(self)
                  self.events.changed.trigger(self)
  
      def button_release(self, event):
          """whenever a mouse button is released"""
          picked = self.picked
          super(ResizableDraggableWidgetBase, self).button_release(event)
          if event.button != 1:
              return
          if picked and self.picked is False:
              if self.no_events_while_dragging and self._drag_store:
                  self._apply_changes(*self._drag_store)
  
  
  class Widget2DBase(ResizableDraggableWidgetBase):
  
      """A base class for 2D widgets. It sets the right dimensions for size and
      position, adds the 'border_thickness' attribute and initalizes the 'axes'
      attribute to the first two navigation axes if possible, if not, the two
      first signal_axes are used. Other than that it mainly supplies common
      utility functions for inheritors, and implements required functions for
      ResizableDraggableWidgetBase.
  
      The implementation for ResizableDraggableWidgetBase methods all assume that
      a Rectangle patch will be used, centered on position. If not, the
      inheriting class will have to override those as applicable.
      """
  
      def __init__(self, axes_manager, **kwargs):
          super(Widget2DBase, self).__init__(axes_manager, **kwargs)
          self.border_thickness = 2
  
          # Set default axes
          if self.axes_manager is not None:
              if self.axes_manager.navigation_dimension > 1:
                  self.axes = self.axes_manager.navigation_axes[0:2]
              elif self.axes_manager.signal_dimension > 1:
                  self.axes = self.axes_manager.signal_axes[0:2]
              elif len(self.axes_manager.shape) > 1:
                  self.axes = (self.axes_manager.signal_axes +
                               self.axes_manager.navigation_axes)
              else:
                  raise ValueError("2D widget needs at least two axes!")
          else:
              self._pos = np.array([0, 0])
              self._size = np.array([1, 1])
  
      def _get_patch_xy(self):
          """Returns the xy position of the widget. In this default
          implementation, the widget is centered on the position.
          """
          return self._pos - self._size / 2.
  
      def _get_patch_bounds(self):
          """Returns the bounds of the patch in the form of a tuple in the order
          left, top, width, height. In matplotlib, 'bottom' is used instead of
          'top' as the naming assumes an upwards pointing y-axis, meaning the
          lowest value corresponds to bottom. However, our widgets will normally
          only go on images (which has an inverted y-axis in MPL by default), so
          we define the lowest value to be termed 'top'.
          """
          xy = self._get_patch_xy()
          xs, ys = self.size
          return (xy[0], xy[1], xs, ys)        # x,y,w,h
  
      def _update_patch_position(self):
          if self.is_on() and self.patch:
              self.patch[0].set_xy(self._get_patch_xy())
              self.draw_patch()
  
      def _update_patch_size(self):
          self._update_patch_geometry()
  
      def _update_patch_geometry(self):
          if self.is_on() and self.patch:
              self.patch[0].set_bounds(*self._get_patch_bounds())
              self.draw_patch()
  
  
  class ResizersMixin(object):
      """
      Widget mix-in for adding resizing manipulation handles.
  
      The default handles are green boxes displayed on the outside corners of the
      boundaries. By default, the handles are only displayed when the widget is
      selected (`picked` in matplotlib terminology).
  
      Attributes:
      -----------
          resizers : {bool}
              Property that determines whether the resizer handles should be used
          resize_color : {matplotlib color}
              The color of the resize handles.
          resize_pixel_size : {tuple | None}
              Size of the resize handles in screen pixels. If None, it is set
              equal to the size of one 'data-pixel' (image pixel size).
          resizer_picked : {False | int}
              Inidcates which, if any, resizer was selected the last time the
              widget was picked. `False` if another patch was picked, or the
              index of the resizer handle that was picked.
  
      """
  
      def __init__(self, resizers=True, **kwargs):
          super(ResizersMixin, self).__init__(**kwargs)
          self.resizer_picked = False
          self.pick_offset = (0, 0)
          self.resize_color = 'lime'
          self.resize_pixel_size = (5, 5)  # Set to None to make one data pixel
          self._resizers = resizers
          self._resizer_handles = []
          self._resizers_on = False
          # The `_resizers_on` attribute reflects whether handles are actually on
          # as compared to `_resizers` which is whether the user wants them on.
          # The difference is e.g. for turning on and off handles when the
          # widget is selected/deselected.
  
      @property
      def resizers(self):
          return self._resizers
  
      @resizers.setter
      def resizers(self, value):
          if self._resizers != value:
              self._resizers = value
              self._set_resizers(value, self.ax)
  
      def _update_resizers(self):
          """Update resizer handles' patch geometry.
          """
          pos = self._get_resizer_pos()
          rsize = self._get_resizer_size()
          for i, r in enumerate(self._resizer_handles):
              r.set_xy(pos[i])
              r.set_width(rsize[0])
              r.set_height(rsize[1])
  
      def _set_resizers(self, value, ax):
          """Turns the resizers on/off, in much the same way that _set_patch
          works.
          """
          if ax is not None:
              if value:
                  for r in self._resizer_handles:
                      ax.add_artist(r)
                      r.set_animated(hasattr(ax, 'hspy_fig'))
              else:
                  for container in [
                          ax.patches,
                          ax.lines,
                          ax.artists,
                          ax.texts]:
                      for r in self._resizer_handles:
                          if r in container:
                              container.remove(r)
              self._resizers_on = value
              self.draw_patch()
  
      def _get_resizer_size(self):
          """Gets the size of the resizer handles in axes coordinates. If
          'resize_pixel_size' is None, a size of one pixel will be used.
          """
          invtrans = self.ax.transData.inverted()
          if self.resize_pixel_size is None:
              rsize = [ax.scale for ax in self.axes]
          else:
              rsize = np.abs(invtrans.transform(self.resize_pixel_size) -
                             invtrans.transform((0, 0)))
          return rsize
  
      def _get_resizer_offset(self):
          """Utility for getting the distance from the boundary box to the
          center of the resize handles.
          """
          invtrans = self.ax.transData.inverted()
          border = self.border_thickness
          # Transform the border thickness into data values
          dl = np.abs(invtrans.transform((border, border)) -
                      invtrans.transform((0, 0))) / 2
          rsize = self._get_resizer_size()
          return rsize / 2 + dl
  
      def _get_resizer_pos(self):
          """Get the positions of the resizer handles.
          """
          invtrans = self.ax.transData.inverted()
          border = self.border_thickness
          # Transform the border thickness into data values
          dl = np.abs(invtrans.transform((border, border)) -
                      invtrans.transform((0, 0))) / 2
          rsize = self._get_resizer_size()
          xs, ys = self._size
  
          positions = []
          rp = np.array(self._get_patch_xy())
          p = rp - rsize + dl                         # Top left
          positions.append(p)
          p = rp + (xs - dl[0], -rsize[1] + dl[1])    # Top right
          positions.append(p)
          p = rp + (-rsize[0] + dl[0], ys - dl[1])    # Bottom left
          positions.append(p)
          p = rp + (xs - dl[0], ys - dl[1])           # Bottom right
          positions.append(p)
          return positions
  
      def _set_patch(self):
          """Creates the resizer handles, irregardless of whether they will be
          used or not.
          """
          if hasattr(super(ResizersMixin, self), '_set_patch'):
              super(ResizersMixin, self)._set_patch()
  
          if self._resizer_handles:
              self._set_resizers(False, self.ax)
          self._resizer_handles = []
          rsize = self._get_resizer_size()
          pos = self._get_resizer_pos()
          for i in range(len(pos)):
              r = plt.Rectangle(pos[i], rsize[0], rsize[1], animated=self.blit,
                                fill=True, lw=0, fc=self.resize_color,
                                picker=True,)
              self._resizer_handles.append(r)
  
      def set_on(self, value):
          """Turns on/off resizers whet widget is turned on/off.
          """
          if self.resizers and value != self._resizers_on:
              self._set_resizers(value, self.ax)
          if hasattr(super(ResizersMixin, self), 'set_on'):
              super(ResizersMixin, self).set_on(value)
  
      def onpick(self, event):
          """Picking of main patch is same as for widget base, but this also
          handles picking of the resize handles. If a resize handles is picked,
          `picked` is set to `True`, and `resizer_picked` is set to an integer
          indicating which handle was picked (0-3 for top left, top right, bottom
          left, bottom right). It is set to `False` if another widget was picked.
  
          If the main patch is picked, the offset from the picked pixel to the
          `position` is stored in `pick_offset`. This can be used in e.g.
          `_onmousemove` to ease dragging code (prevent widget center/corner
          snapping to mouse).
          """
          if event.artist in self._resizer_handles:
              corner = self._resizer_handles.index(event.artist)
              self.resizer_picked = corner
              self.picked = True
          elif self.picked:
              if self.resizers and not self._resizers_on:
                  self._set_resizers(True, self.ax)
              x = event.mouseevent.xdata
              y = event.mouseevent.ydata
              self.pick_offset = (x - self._pos[0], y - self._pos[1])
              self.resizer_picked = False
          else:
              self._set_resizers(False, self.ax)
          if hasattr(super(ResizersMixin, self), 'onpick'):
              super(ResizersMixin, self).onpick(event)
  
      def _add_patch_to(self, ax):
          """Same as widget base, but also adds resizers if 'resizers' property
          is True.
          """
          if self.resizers:
              self._set_resizers(True, ax)
          if hasattr(super(ResizersMixin, self), '_add_patch_to'):
              super(ResizersMixin, self)._add_patch_to(ax)
  