Help in wxpython

[madhura vadvalkar]

Hi

I am trying to write an PAINT like application where on the mouse
click a circle is drawn on canvas. I am new to python and using
wxpython to create this.

here is the code:

import wx

class SketchWindow(wx.Window):

def __init__ (self, parent,ID):

wx.Window.__init__(self, parent, ID)

self.panel =wx.Panel(self, size= (350,350))
self.pen=wx.Pen( 'blue',4)
self.pos=(0,0)
self.InitBuffer()
self.Bind(wx.EVT_LEFT_DOWN,self.OnLeftDown)

def InitBuffer(self):

size=self.GetClientSize()
self.Buffer=wx.EmptyBitmap(size.width,size.height)
dc=wx.BufferedDC(None,self.buffer)
dc.SetBackground(wx.Brush(self.GetBackgroundColour()))
dc.Clear()
self.Drawcircle(dc)
self.reInitBuffer=False

def OnLeftDown(self,event):
self.pos=event.GetPositionTuple()
self.CaptureMouse()

def Drawcircle(self,dc):
pen=wx.Pen(colour,thickness,wx.SOLID)
dc.SetPen(pen)
dc.DrawCircle(self.pos.x,self.pos.y,r)

class SketchFrame(wx.Frame):
def __init__(self, parent):

wx.Frame.__init__(self, parent, -1, "Sketch Frame",size=(800,600))
self.sketch = SketchWindow(self, -1)

if __name__=='__main__':
app=wx.PySimpleApp()
frame=SketchFrame(None)
frame.Show(True)
app.MainLoop()

I am getting the following error:

Traceback (most recent call last):
File "C:/Python26/circle.py", line 42, in <module>
frame=SketchFrame(None)
File "C:/Python26/circle.py", line 38, in __init__
self.sketch = SketchWindow(self, -1)
File "C:/Python26/circle.py", line 12, in __init__
self.InitBuffer()
File "C:/Python26/circle.py", line 19, in InitBuffer
dc=wx.BufferedDC(None,self.buffer)
AttributeError: 'SketchWindow' object has no attribute 'buffer'

Please tell me what I am doing wrong.

Thanks