matplotlib: how to refresh figure.canvas

Question

I can't understand how to refresh FigureCanvasWxAgg instance. Here is the example:

import wx
import matplotlib
from matplotlib.backends.backend_wxagg import FigureCanvasWxAgg as FigureCanvas
from matplotlib.figure import Figure

class MainFrame(wx.Frame): 
    def __init__(self): 
        wx.Frame.__init__(self, None, wx.NewId(), "Main") 
        self.sizer = wx.BoxSizer(wx.VERTICAL)

        self.figure = Figure(figsize=(1,2))
        self.axe = self.figure.add_subplot(111)
        self.figurecanvas = FigureCanvas(self, -1, self.figure)

        self.buttonPlot = wx.Button(self, wx.NewId(), "Plot")
        self.buttonClear = wx.Button(self, wx.NewId(), "Clear")

        self.sizer.Add(self.figurecanvas, proportion=1, border=5, flag=wx.ALL | wx.EXPAND)
        self.sizer.Add(self.buttonPlot, proportion=0, border=2, flag=wx.ALL)
        self.sizer.Add(self.buttonClear, proportion=0, border=2, flag=wx.ALL)
        self.SetSizer(self.sizer)

        self.figurecanvas.Bind(wx.EVT_LEFT_DCLICK, self.on_dclick)
        self.buttonPlot.Bind(wx.EVT_BUTTON, self.on_button_plot)
        self.buttonClear.Bind(wx.EVT_BUTTON, self.on_button_clear)

        self.subframe_opened = False

    def on_dclick(self, evt):
        self.subframe = SubFrame(self, self.figure)
        self.subframe.Show(True)
        self.subframe_opened = True

    def on_button_plot(self, evt):
        self.axe.plot(range(10), color='green')
        self.figurecanvas.draw()

    def on_button_clear(self, evt):
        if self.subframe_opened:
            self.subframe.Close()
        self.figure.set_canvas(self.figurecanvas)
        self.axe.clear()
        self.figurecanvas.draw()


class SubFrame(wx.Frame): 
    def __init__(self, parent, figure): 
        wx.Frame.__init__(self, parent, wx.NewId(), "Sub")
        self.sizer = wx.BoxSizer(wx.VERTICAL)
        self.figurecanvas = FigureCanvas(self, -1, figure)
        self.sizer.Add(self.figurecanvas, proportion=1, border=5, flag=wx.ALL | wx.EXPAND)
        self.SetSizer(self.sizer)

        self.Bind(wx.EVT_CLOSE, self.on_close)

    def on_close(self, evt):
        self.GetParent().subframe_opened = False
        evt.Skip()



class MyApp(wx.App):
    def OnInit(self):
        frame = MainFrame()
        frame.Show(True)
        self.SetTopWindow(frame)
        return True

app = MyApp(0)
app.MainLoop()    

I'm interested in the following sequence of operations:

• run a script
• resize the main frame
• press Plot button
• double click on plot
• press Clear button

Now I get a mess on main frame plot. If I resize the frame it redraws properly. My question is what should I add to my code to do that without resizing?

By a "mess" I mean something like this:

http://img227.imageshack.us/img227/5407/mess.png

Thanks in advance.

Answer 1

As I said in the comments, I don't think that the figure canvas refresh is your problem, in fact I think it's doing exactly what it's supposed to (redrawing itself based on it's last state [ie as it was in your subplot]). I think your problem is more that the wxFrame is not refreshing.

The easiest way to fix that would be to make it resize itself on your "Clear" event. Something like:

def on_button_clear(self, evt):
    if self.subframe_opened:
        self.subframe.Close()
    self.figure.set_canvas(self.figurecanvas)
    self.axe.clear()
    self.figurecanvas.draw()  
    self.SetSize((self.Size[0],self.figurecanvas.Size[1]))

The set size would cause the frame and all the controls it contains to be redrawn.

That said, I think sharing your figure between the two figurecanvas is dangerous. I was able to produce some serious errors by clicking/resizing things in different combinations. On occasion your figure would be garbage collected when the subframe was closed, making it unavailable to your main frame.