wxpython - draw lines on image

[dazzler]

I'm trying to draw line to an existing image, the problem is that the image doesn't update/refresh itself.

In the example there's one button, but when pressing the button it changes the image but the image doesn't show up, and if I move other windows over my application window it will then refresh my application window and reveals the image.

so what I'm trying to do is animating (moving) a line over existing image

also, I don't want to load image everytime I draw on to it, need to make a copy of the loaded image somehow?

problems are commented in the example code

import wx
 
class MyFrame(wx.Frame):
   def __init__(self):
 
      self.frame1 = wx.Frame(None, title="test", id=-1, size=(700, 500))
      self.panel1 = wx.Panel(self.frame1)
 
      Button1 = wx.Button(self.panel1, -1, "update photo", (150,420))
      Button1.Bind(wx.EVT_BUTTON, self.update_pic)
 
      self.statbmp = wx.StaticBitmap(self.panel1, id=-1, pos=(500,250), size=(150,150))
 
      self.image = wx.Bitmap("photo.bmp")
      canvas_dc = wx.MemoryDC(self.image)
      canvas_dc.DrawBitmap(self.image, 0, 0)
      canvas_dc.DrawLine(x1=75, y1=97, x2=12, y2=31)
      self.statbmp.SetBitmap(self.image)
 
      self.frame1.Show(True)
 
   def update_pic(self, event):
 
      self.image = wx.Bitmap("photo.bmp")   # I don't want load this from Harddisk everytime, how to load this from memory
      canvas_dc = wx.MemoryDC(self.image)
      canvas_dc.DrawBitmap(self.image, 0, 0)
      canvas_dc.DrawLine(x1=75, y1=97, x2=22, y2=31)
      self.statbmp.SetBitmap(self.image) #Image don't get updated/refreshed(?), I see only white blank space
 
app = wx.PySimpleApp()
f = MyFrame()
app.MainLoop()