[cairo] Wanted features in Cairo.

[Jeff Muizelaar]

> to break gmane's top posting detection...

I still can't send mail to the cairo mailing list using my regular account. It
looks like the problem is dns related...

Anyways,

Miguel de Icaza <miguel <at> ximian.com> writes:

> 
> Hey folks,
> 
>     As part of our effort to implement Silverlight in Linux we have run
> into a few things that would be nice to have in Cairo and Behdad
> suggested that I post these to the list.
> 
> * Line caps
> 
>     A feature that we are currently missing is the ability to use
> different line caps for the beginning and end of a drawing.   Cairo
> currently only offers one option: cairo_set_line_cap and we would need
> to have separate versions for the beginning and end.

What would dashing look like? Something like:
[==) [==) [==)
where the start cap is butt and the end cap is round?

Capping degenerate segments shouldn't be a problem.

The biggest problem I see is implementing different start and end
caps in postscript/PDF and perhaps SVG. Do you know if XPS supports
different start and end caps? If it does what kind of postscript is
generated when printing them?

> * Alpha painting
> 
>     Currently Cairo has a couple of functions for setting its source: 
> 
> 	set_source_rgb
> 	set_source_rgba    <- With alpha
> 
> 	set_source	   <- from pattern
> 	set_source_surface <- from surface
> 
>     We would like to have parity in set_source and set_source_surface in
> terms of using the pattern/surface with an alpha channel.
> 
>     It is not absolutely mandatory to have them, but it would clean up
> some of the code that we have right now and the creation of temporary
> buffers to get the painting on the screen with alpha transparency.

Does cairo_paint_with_alpha() suit your needs? If not, why?

> 
> We will try to provide some more feedback as we get more solid data for
> you guys regarding performance.

That will be interesting to see. Make sure you also test with cairo git
as some performance problems have been fixed since the last stable
release.

-Jeff