[wxPython-users] Problem with device context program - doesn't display what i want

[Christopher Barker]

Jason Wang wrote:
> I still can't make it work even if i added the
> OnSize() method and attached the event, attached is my code.

The attachment didn't come through.

> Also, i have another question, why does some of the code i read has
> dc.BeginDrawing() and dc.EndDrawing()? Do i have to have that around
> my Draw() method?

NO, you don't. Those calls once provided some optimization on some 
platforms, but I think they do nothing anywhere now. In any case, your 
code should work with or without them.

> I also read the DoubleBufferedDrawing page, it is apparently a general
> class which you can subclass and work with it, i didn't get it to
> work,

Darn. Platform, Version? what "didn't work"

It's a pretty simple class really. It could well be useful to subclass, 
but was designed as a teaching example, more than anything.

 > It looks pretty different from mine.

A little extra stuff, the but the basics are the same.

by the way, I find it's easiest to learn this stuff by adding things a 
little at a time. Your post said you were trying to learn about DCs. Why 
not start with a non-buffered example, so you can figure out the drawing 
first, then apply it to double buffering. About the easiest example I 
can come up with for drawing is:

#!/usr/bin/env python2.4

import wx

class DemoFrame(wx.Frame):
     """ This window does some simple drawing """
     def __init__(self, *args, **kwargs):
         wx.Frame.__init__(self, *args, **kwargs)


         self.Bind(wx.EVT_PAINT, self.OnPaint)

     def OnPaint(self, event):
         dc = wx.PaintDC(self)

         dc.SetPen(wx.BLACK_PEN)
         dc.SetBrush(wx.RED_BRUSH)
         dc.DrawRectangle(20,30, 100, 40)

app = wx.App()
frame = DemoFrame(None, size = (200, 200))
frame.Show()
app.MainLoop()


-Chris


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Christopher Barker, Ph.D.
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