text: '''
      Gui/Views/Visualizer/Trees/zoom
      _______________________________
  
      Methods for custom zoom events (such as zoom to percent).
  
      :copyright: (c) 2015 The Regents of the University of California.
      :license: GNU GPL, see licenses/GNU GPLv3.txt for more details.
  '''
  
  # load modules
  from xldlib.qt.objects import base
  from xldlib.utils import logger
  
  
  # METHODS
  # -------
  
  
  @logger.init('document', 'DEBUG')
  class ZoomTools(base.BaseObject):
      '''Toolkit for zoom events on the PyQtGraph'''
  
      #  PUBLIC FUNCTIONS
  
      @logger.except_error(AttributeError)
      def zoomin(self, percentage=0.1, axis='x'):
          self.canvas().zoomin(percentage, axis)
  
      @logger.except_error(AttributeError)
      def zoomout(self, percentage=0.1, axis='x'):
          self.canvas().zoomout(percentage, axis)
  
      @logger.except_error(AttributeError)
      def home(self):
          return self.canvas().home()
  
      @logger.except_error(AttributeError)
      def next(self):
          return self.canvas().next()
  
      @logger.except_error(AttributeError)
      def previous(self):
          return self.canvas().previous()
  
      #     HELPERS
  
      def widget(self):
          return self.parent().visualizer_view.widget
  
      def canvas(self):
          return self.widget().canvas
  