----- Original Message -----
From: "Robin Dunn" <robin@[...].com> 
To: <wxpython-users@[...].org> 
Sent: Tuesday, April 30, 2002 12:06 AM
Subject: Re: [wxPython] DrawLines and a bunch points


>  >
>  > All this background to ask some non-wxPython questions (though
>  related...):
>  >
>  >     1.  Can anyone verify that they get the same behavior with
>  >         DrawLines?  <I wondering if something is strange about
>  >         my machine setup>
> 
>  I always get between 0.25 and 0.60, depending on how much area needs
>  refreshed.

Thanks for the test.  It sounds like an idiosyncrasy of my machine.  I guess
that is better news than the alternative...

> 
>  >     2.  Does anyone have any insight into what is going on here?
>  >
> 
>  Not really.  There is some (probably) unnecessary overhead there though.
>  wxPython's DrawLines transforms the sequence into an array of wxPoint
>  objects and then calls the C++ DrawLines.  (On MSW the wxPoint object is the
>  same structure as MSW's POINT so another transform to call Polyline is not
>  needed.)

Right.  Well, for now, the extra overhead is a minor issue compared to the
PolyLine problem.  weave provides a way around the extra overhead in the final
tweaking stages, but, for now, I'm more interested in just getting the project
working with reasonable performance.

> 
>  >          a. Why is PolyLine fast for the initial call and slow for
>  >             subsequent calls with a large number of points?
>  >
>  >          b. Why is PolyLine slow for a large number of points?
>  >             Heck, 30000 isn't even all that large of a number.
> 
>  No idea.

Dag.  Me neither.

> 
>  >
>  >     3.  Does Linux have the same problem?
> 
>  I don't have Numeric installed there, so I don't know.
> 
>  >
>  >     4.  Am I missing an extra call somewhere that would fix all my
>  >         problems?
> 
>  We added DrawLineList to wxPython's DC in 2.3.2 or .1 that doesn't have the
>  transformation overhead described above.  It takes a sequence of
>  (x1,y1,x2,y2) sequences, and optionally a list of pens, and iterates through
>  it calling DrawLine.  You end up with a ton more win32 API calls, but no
>  transformation.

It doesn't sound like this is as good of a solution for drawing an array of
points.  I'll stick with DrawLines.

thanks for your help,
eric





_______________________________________________
wxpython-users mailing list
wxpython-users@[...].org
http://lists.wxwindows.org/mailman/listinfo/wxpython-users