Re: [matplotlib-devel] Re: PS backend wish list

[Matt N. <new...@ca...>]

Hi John,

Hmm, could be.  Text is definitely slow, but my recollection is
that the Line2D drawing of the ticks was actually significant.
For example, the speed difference when turning on/off the right
and top ticks (which don't generally have text) was noticeable.

It's been awhile since I looked at this, and I'm not finding my
test scripts right now.  My conclusions at the time were that
agg rendering was dominating WXAgg time (so improving the WXAgg
icky get-rgb-image-then-render-as-bitmap was not so slow) and
that tick line rendering in Agg was much slower than I had
expected.  I'll try to reproduce this, but this week is sort of
full for me.  Currently, line plotting with WXAgg is fast enough
for me (I can reliably get better than 10 plots/sec on WinXP in
my app, for example).

Also, just to be clear: I owe you much more than doughnuts.
Thanks,

--Matt

On Mon, 4 Apr 2005, John Hunter wrote:

> >>>>> "Matt" == Matt Newville <new...@ca...> writes:
> 
>     Matt> I like Darren's and Paul's suggestion (set line properties
>     Matt> once, then have the ticks be a simple list of pen up / pen
>     Matt> down).  I believe major and minor ticks would need to have
>     Matt> different properties, but it's still only 2 set of
>     Matt> properties. I understand that this might mean a significant
>     Matt> redesign, but the performance boost might be worth it.
> 
> I would bet dollars to doughnuts (careful here, Perry still owes me a
> doughnut!) that almost all of the tick cost comes from laying out the
> text of the ticks and not in drawing the tick lines themselves -- Arnd
> posted some hotshot profile of this earlier, but I don't remember the
> exact results).
> 
> I agree ticks (and text in general) are too expensive.  In my
> experience, this is usually only starts a problem in animated plots
> (do you have another use case in mind?).  I think we might be able to
> work around this particular problem by supporting the drawing of only
> a subset of the artists in the scene.  I imagine something like the
> following is workable.
> 
>   line, = ax.plot(blah)
> 
>   dynamic = (line,)  # a list of artists to animate
>   # draws everything but artists in dynamic and caches Axes bbox to bitmap
>   ax.animate_prepare( dynamic) 
> 
>   while 1:
>      line.set_data(blah)
>      # blits the axes background cache and renders only the artists in dynamic
>      ax.animate()  
> 
> 
> I'm not opposed to a redesign of the Tick drawing if there are
> appreciable gains to be had, but my guess is we may get more bang for
> the buck in special casing the typical text layout (angle=0.0, no
> mathtext, no unicode) and handling dynamic updates more intelligently.
> 
> JDH
> 
> 
> 
> 
> 
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