matplotlib-devel Mailing List for matplotlib

On Sat, 2007年01月06日 at 09:23 -1000, Eric Firing wrote:
> Steve,
> 
> Darren Dale raised a question offline that I think will be of general 
> interest to mpl devels, and that you are the person to answer:
> 
> How do you see the future of a cairo backend as a prospective 
> replacement for most or all of the primary mpl backends?
I think cairo could potentially be used to replace the pdf, ps, svg
and gdk/gtk backends which would unify most of the backends and simplify
a lot of the code.
> What would need to be completed in cairo? Based on the cairo web page, I 
> get the impression that quite a bit is still missing, including eps 
> generation and genuine vector ps. But maybe the web page is just out of 
> date.
Which web page is out of date? Where does it mention eps and ps, I
couldn't find it.
My general impression of the cairo "surfaces" is:
ImageSurface/png - support is very good
gtk/xlib - support is very good
ps/pdf/svg are usable but less mature and still developing so there may
 be occasional problems drawing specific items
ps - it used to embed bitmap images but now most output is vector based
eps - is not supported yet, but may be in a future version
> What would need to be done in mpl, and how hard would it be?
The cairo backend can already be used for png, ps, pdf and gtk output so
I don't think there would be much to do. Mostly, it needs testing -
running all the mpl examples and checking the output looks OK.
> Would mpl get slower if everything went through cairo?
Not sure, you would need to run cairo and test it. It used to be much slower
than Agg but more recent versions have had many optimisations applied and
the difference is much smaller now.
> Any other considerations?
Some parts of mpl are Agg-specific and other parts (the whole drawing model)
are designed around the gdk drawing style - this makes things harder and
inefficient when using cairo.
On Sat, 2007年01月06日 at 09:36 -1000, Eric Firing wrote:
> One more question: how does the image quality of cairo compare to
> Agg? 
> Is the antialiasing as good? 
Image quality looks OK to me, but I'm no expert.
The web browser Firefox 3.0 (due to be released early in 2007) will use
cairo for all rendering. Firefox requires a high level of graphics
performance and the upcoming cairo 1.4 release is expected to provide
that.
Steve
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