Re: [matplotlib-devel] Animation for WXAgg

[Ken M. <km...@gm...>]

On Aug 30, 2005, at 9:31 AM, Arnd Baecker wrote:
> Many thanks for the update of the patch.
> It turned out that I could not apply it to this mornings CVS checkout
> because John's time machine was already active  and he has put your
> patch into CVS ;-)

Really?  Yay for me!  ;-)

> During installation I encountered two glitches:
>
> a) debian problem:
>    Very interestingly debian stable (sarge)
>    does not have wxPython.h

It does have wxPython.h, it's just not in the libwxgtk2.4 package.  
You'll need to install the libwxgtk2.4-dev package as well to get the 
headers.

>   GTKAgg               FPS: 131.897223221
>   TkAgg                FPS:  65.5153012595
>   WXAgg                FPS: 100.55
>      (200 frames: 1.99 seconds,   200 blits:  0.95 seconds)
>      (FPS: 100.55                 BPS: 211.00)
>   WXAgg --no-accel     FPS: 53.21
>      (200 frames: 3.76 seconds,   200 blits:  2.55 seconds
>      (FPS: 53.21                  BPS: 78.40)
>
>
> I am running debian sarge, on a PIV, 2.8 GHz and an nVdia Quadro4 NVS
> graphics card (@1600x1200).
> So WXAgg is almost on par with GTGAgg - great!!

That's very exciting news.  I hadn't had a chance to test and profile 
the accelerator under Debian, nor had I bothered profiling it against 
GtkAgg and TkAgg under OSX.  I should probably get those backends up 
and running (darn macs) and do so.

> Ken, in _wxagg.cpp you mention that you planned to write a 
> agg_to_wx_bitmap()
> which draws directly to a bitmap, but that this might not speed up 
> things
> much because of: AGG->wx.Image->wx.Bitmap before you can blit using a 
> MemoryDC.

Yes, I am concerned that re-implementing that part of the blit into C++ 
won't speed things up enough.  I can understand doing the whole 
Image/Bitmap thing for portability (especially when wxWindows got 
started in 1992), but it's rather obnoxious when all it does is make 
extra copies of RGB data.  However, I think there are a couple pieces 
of lower-handing fruit, like not making an extra source copy when 
blitting (_wxagg.cpp:159-190), that will offer speedups.  
Unfortunately, they'd be portable across Agg backends, so GtkAgg would 
get faster too.  ;-)

> Maybe you can contact Chris Barker if he has an idea on this (or are 
> there any
> solutions available in the context of wxart2d or chaco? - quick 
> googling did not
> reveal anything ...)

I'll do so, if he doesn't see this part of the message than chime in.  
I have come across some old wxWindows mailing list exchanges indicating 
that there's no way to avoid the Image->Bitmap conversion as a 
requirement for drawing RGB images, so I'm not planning to loose too 
much sleep over it.  I hadn't heard about wxart2d before, but will look 
into it to see how their agg canvas is implemented.  I'll see if I can 
find the chaco repository and do the same there.

Thanks for sharing your anim.py profiling results.  It's heartening to 
see WXAgg's full-redraw speed being limited by the rest of matplotlib, 
rather than the backend.

Ken