Expand the the final kernel4 stage to maintain a per-pixel mask.
Introduce two new path elements, FillMask and FillMaskInv, to fill
the mask. FillMask acts like Fill, while FillMaskInv fills the area
outside the path.
SVG clipPaths is then representable by a FillMaskInv(0.0) for every nested
path, preceded by a FillMask(1.0) to clear the mask.
The bounding box for FillMaskInv elements is the entire screen; tightening of
the bounding box is left for future work. Note that a fullscreen bounding
box is not hopelessly inefficient because completely filling a tile with
a mask is just a single CmdSolidMask per tile.
Fixes#30
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Trying to fit it into the fancy monad doesn't really work, so use a
more straightforward approach to compute it from the aggregate.
Also add yEdge logic (basically copying piet-metal). With a fix to
ELEMENT_BINNING_RATIO (which I had simply gotten wrong), the example
renders almost correctly, with small bounding box artifacts.
Write the right_edge to the binning output.
More work on encoding the fill/stroke distinction and plumbing that
through the pipeline. This is a bit unsatisfying because of the code
duplication; having an extra fill/stroke bool might be better, but I
want to avoid making the structs bigger (this could be solved by
better packing in the struct encoding).
Fills are plumbed through to the last stage. Backdrop is WIP.
This should get the "right_edge" value for each segment plumbed through
to the binning phase. It also needs to be plumbed to coarse raster and
wired up there.
Also considering WIP because none of this logic has been tested yet.
