Re: [matplotlib-devel] New backend API

[Darren D. <dd...@co...>]

On Monday 03 April 2006 22:16, John Hunter wrote:
> >>>>> "Darren" == Darren Dale <dd...@co...> writes:
>     Darren> Also, if I do the transform in backend_ps, instead of
>     Darren> passing it to the postscript interpreter, I see a big
>     Darren> speedup at render time. Right now I am doing this
>     Darren> transform by hand:
>
>     Darren> a,b,c,d,tx,ty=vec6 xo = a*x+c*y +tx yo = b*x+d*y + ty x,y
>     Darren> = xo,yo
>
>     Darren> Is there a better way to do this? I thought I could simply
>     Darren> call numerix_x_y, but that function is not compatible with
>     Darren> nonlinear transforms (returns a domain error if one of the
>     Darren> axes is log-scaled).
>
> You can transform the xy values point by point.  Instead of separating
> them into their nonlinear and affine components as we are currently
> doing in backend_ps, you can call trans.xy_tup which will do both.  If
> successful, it will return the transformed xy, if it fails, it will
> raise a ValueError, and you can set the moveto/lineto state
> accordingly.

I see a draw_lines_testing in backend_ps. I think it could be a good approach, 
but it doesnt make it very easy to skip unplottable elements like nans, infs. 
Could xy_tup accept a kwarg to make it raise an error when it tries to 
transform an inf or a nan?

Darren