[cairo] GSoC: Scan converting rasteriser update

[M Joonas Pihlaja]

On Sat, 8 Nov 2008, Jeff Muizelaar wrote:

> [cairo-spans] New _cairo_path_fixed_fill_to_span_renderer().
> - OUT_self doesn't really follow a the cairo style
> - OUT_converter in _begin_rendering()

OK.

> - I wonder if _cairo_path_fixed_fill_to_span_renderer() would be simpler if
>  _begin_rendering and _end_rendering were not split out. I think it could
>  simplify the error handling.

They're left over from the ..._stroke_to_span_renderer() I took 
out.

> [cairo-spans] New cairo_delta_spans_t.
> - I need to look at this more

That's on its way out.  I'm thinking I should take the tor scan 
converter and shake out a mono one from it, and at that point the 
current mono scan converter and delta spans can go away.

> [cairo-spans] Render clip mask surfaces with spans if we can.
> - _cairo_clip_intersect_mask_with_spans() isn't a good name
>  it makes it sound like we are intersecting the mask the some spans
>  when in fact we are doing an intersect between two masks()
>  using a span renderer

I chose that as an alternate implementation of 
_cairo_clip_intersect_mask().  Any suggestions for a good name?

> - can we use SRC to an unitialized surface instead of initializing a surface
>  and then doing ADD?

Uninitialised surfaces wouldn't work since SOURCE is defined to 
be bounded by the mask.  Can we add an unbounded SOURCE at some 
point to cairo?

> - we should also probably not construct a new surface unless the new clip
>  is much smaller than the current clip otherwise it feels like we are wasting
>  our time constructing a new clip when the old one will do.

But that's how cairo-clip.c works?  Duplicating/cloning a clip 
needs to be fast since it's done by cairo_save()/restore(), so 
we're doing only shallow copies then and sharing the mask 
surfaces of the clip.  We could optimise the case when the 
current cairo_clip_t has the only reference to the surface, but 
I'd add that as a separate thing.

Joonas