[wxPython-users] Re: Trouble with drawing, I need some ideas :)

[Robin Dunn]

Peter Damoc wrote:
> Hi Robin,
> First, let me apologize for not being clear again. :)
> 
> I appreciate the advice you gave BUT it is not touching the real issue.
> The sample created was just some boiler plate for people to play with. 
> It was not "efficient".
> I can do all the buffering that could be done BUT my main issue remains 
> the same:
> 
> How do I use alpha in a buffer that need to be blited over some other 
> drawing? Color based transparency won't do because of the wxGCDC used in 
> the buffer.
> 
> Here... take a look at this kind of desperate code:
> 
>         cache = wx.MemoryDC(wx.EmptyBitmap(w,h))       
>         cache.SetBackground(wx.TRANSPARENT_BRUSH)
>         cache.SetBackgroundMode(wx.TRANSPARENT )
>         cache.Clear()
>         gc_cache  = wx.GCDC(cache)
>         gc_cache.SetBackground(wx.TRANSPARENT_BRUSH)
>         gc_cache.SetBackgroundMode(wx.TRANSPARENT)
>         gc_cache.Clear()
> 
> Maybe it expresses what I'm trying to accomplish.

I see you found a solution, but to help clarify this for you let me 
point out that using a transparent brush simply means "don't draw 
anything", not "change these pixels to transparent".

-- 
Robin Dunn
Software Craftsman
http://wxPython.org  Java give you jitters?  Relax with wxPython!