扩展matplotlib工具栏缩放功能

Question

将工具栏添加到画布。缩放的默认功能是缩放，如何扩展此功能？如果我重新定义缩放比例，它将使用默认功能。

class correlator_toolbar(NavigationToolbar2TkAgg):
    def __init__(self,canvas_,parent_,):
        global toolitems

        toolitems = self.toolitems = (
            ('Home', 'Show home state', 'home', 'home'),
            ('Zoom', 'Zoom to rectangle', 'zoom_to_rect', 'zoom'),
            )
        NavigationToolbar2TkAgg.__init__(self,canvas_,parent_)
    def zoom(self):
        print 'something'