title: Python: Striping in bitmap using dc.drawBitMap on a wx.EmptyImage
body: <p>I really don't understand the striping behaviour resulting from the following code. I had rather hoped to see the top half of the bitmap in white, and the bottom half in black. I think I may have misunderstood something fundamental here. Any help gratefully received.</p>
  
  <pre><code>import numpy
  import wx
  
  class MyFrame(wx.Frame):
  def __init__(self, parent, id, title):
      wx.Frame.__init__(self, parent, id, title, size = (135,655))
  
      width = 128
      height = 640
      color = (255,255,255)
  
      array = numpy.zeros((width,height,3),'uint8')
      array[:,:,] = color
      print array[10,10,0]
      array[0:128,0:320,0:3] = 0
      print array[10,10,0]
      image = wx.EmptyImage(width,height)
      image.SetData(array.tostring())
      self.bitmap = image.ConvertToBitmap()
      wx.EVT_PAINT(self, self.OnPaint)
  
      self.Centre()
  
  def OnPaint(self, event):
      dc = wx.PaintDC(self)
      dc.DrawBitmap(self.bitmap,3,10)
  
  class MyApp(wx.App):
      def OnInit(self):
          frame = MyFrame(None, -1, '2DS')
          frame.Show(True)
          self.SetTopWindow(frame)
          return True
  
  app = MyApp(0)
  app.MainLoop()
  </code></pre>