Add new navigate modes in matplotlib

Well here it is, ugly but functional. I'll let the docstrings do the talking, this has wasted enough of my time.

import wx
from matplotlib.patches import Rectangle
from matplotlib.widgets import Lasso
from matplotlib.figure import Figure
from matplotlib.backends.backend_wxagg import FigureCanvasWxAgg
from matplotlib.backends.backend_wxagg import NavigationToolbar2WxAgg

class MyNavToolbar(NavigationToolbar2WxAgg):
    """wx/mpl NavToolbar hack with an additional tools user interaction.
    This class is necessary because simply adding a new togglable tool to the
    toolbar won't (1) radio-toggle between the new tool and the pan/zoom tools.
    (2) disable the pan/zoom tool modes in the associated subplot(s).
    """
    ID_LASSO_TOOL = wx.NewId()
    def __init__(self, canvas):
        super(NavigationToolbar2WxAgg, self).__init__(canvas)

        self.pan_tool  = self.FindById(self._NTB2_PAN)
        self.zoom_tool = self.FindById(self._NTB2_ZOOM)

        self.lasso_tool = self.InsertSimpleTool(5, self.ID_LASSO_TOOL, 
                            wx.ArtProvider.GetBitmap(wx.ART_ADD_BOOKMARK),
                            isToggle=True)
        self.Bind(wx.EVT_TOOL, self.on_toggle_lasso_tool, self.lasso_tool)
        self.Bind(wx.EVT_TOOL, self.on_toggle_pan_zoom, self.zoom_tool)
        self.Bind(wx.EVT_TOOL, self.on_toggle_pan_zoom, self.pan_tool)

    def get_mode(self):
        """Use this rather than navtoolbar.mode
        """
        if self.lasso_tool.IsToggled():
            return 'lasso'
        else:
            return self.mode

    def untoggle_mpl_tools(self):
        """Hack city: Since I can't figure out how to change the way the 
        associated subplot(s) handles mouse events: I generate events to turn
        off whichever tool mode is enabled (if any). 
        This function needs to be called whenever any user-defined tool 
        (eg: lasso) is clicked.
        """
        if self.pan_tool.IsToggled():
            wx.PostEvent(
                self.GetEventHandler(), 
                wx.CommandEvent(wx.EVT_TOOL.typeId, self._NTB2_PAN)
            )
            self.ToggleTool(self._NTB2_PAN, False)
        elif self.zoom_tool.IsToggled():
            wx.PostEvent(
                self.GetEventHandler(),
                wx.CommandEvent(wx.EVT_TOOL.typeId, self._NTB2_ZOOM)
            )
            self.ToggleTool(self._NTB2_ZOOM, False)

    def on_toggle_lasso_tool(self, evt):
        """Lasso tool handler.
        """
        if evt.Checked():
            self.untoggle_mpl_tools()

    def on_toggle_pan_zoom(self, evt):
        """Called when pan or zoom is toggled. 
        We need to manually untoggle user-defined tools.
        """
        if evt.Checked():
            self.ToggleTool(self.ID_LASSO_TOOL, False)
        # Make sure the regular pan/zoom handlers get the event
        evt.Skip()

class ScatterPanel(FigureCanvasWxAgg):
    """Contains the guts for drawing scatter plots.
    """
    def __init__(self, parent, **kwargs):
        self.figure = Figure()
        FigureCanvasWxAgg.__init__(self, parent, -1, self.figure, **kwargs)
        self.canvas = self.figure.canvas
        self.SetMinSize((100,100))
        self.figure.set_facecolor((1,1,1))
        self.figure.set_edgecolor((1,1,1))
        self.canvas.SetBackgroundColour('white')

        self.subplot = self.figure.add_subplot(111)
        self.navtoolbar = None
        self.lasso = None
        self.redraw()

        self.canvas.mpl_connect('button_press_event', self.on_press)
        self.canvas.mpl_connect('button_release_event', self.on_release)

    def lasso_callback(self, verts):
        pass

    def on_press(self, evt):
        """canvas mousedown handler
        """
        if evt.button == 1:
            if self.canvas.widgetlock.locked(): 
                return
            if evt.inaxes is None: 
                return
            if self.navtoolbar and self.navtoolbar.get_mode() == 'lasso':
                self.lasso = Lasso(evt.inaxes, (evt.xdata, evt.ydata), self.lasso_callback)
                self.canvas.widgetlock(self.lasso)

    def on_release(self, evt):
        """canvas mouseup handler
        """
        # Note: lasso_callback is not called on click without drag so we release
        #   the lock here to handle this case as well.
        if evt.button == 1:
            if self.lasso:
                self.canvas.draw_idle()
                self.canvas.widgetlock.release(self.lasso)
                self.lasso = None
        else:
            self.show_popup_menu((evt.x, self.canvas.GetSize()[1]-evt.y), None)

    def redraw(self):
        self.subplot.clear()
        self.subplot.scatter([1,2,3],[3,1,2])

    def get_toolbar(self):
        if not self.navtoolbar:
            self.navtoolbar = MyNavToolbar(self.canvas)
            self.navtoolbar.Realize()
        return self.navtoolbar

if __name__ == "__main__":
    app = wx.PySimpleApp()
    f = wx.Frame(None, size=(600,600))
    p = ScatterPanel(f)
    f.SetToolBar(p.get_toolbar())            
    f.Show()
    app.MainLoop()