Alt already deleted regions and pieces of open lines, but erase mode had
no edges of closed shapes, no distinct pointer, highlighted regions in the
merge-mode grey, only noticed Alt on a mouse move, and an erase drag could
flip mode at release. Like the reference app's erase mode:
- pathops::shape_builder(shapes, edges) returns a BuilderArrangement; with
`edges` it also cuts the outlines of closed (and filled open) paths
wherever other paths meet them. pathops::cut_out removes such a piece
from a path: a closed subpath opens there, an open one splits or
shortens, a piece all the way round takes its subpath, and a filled open
path's invisible closing edge never comes back as a visible segment.
Specks where paths only touch cut nothing; a zero-length input is no
longer the source of edges running through it. encloses_area is shared
with the tool's closing of filled open paths.
- BuilderMap (with_edges) hit-tests edges like line pieces (nearest wins);
an erase gesture that crosses an edge into a region deletes the region,
not the edge (erased_edges).
- shapeBuilder.merge {erase}: deletes the edges touched within tolerance
(from every shape along them), after the regions; returns `edges`.
shapeBuilder.regions lists `edges` (bounds, source). One undo step.
- Shape Builder tool: Alt held switches to erase mode and back on release:
red mesh/edge highlights of what will be deleted, a minus pointer
(Cursor::ShapeBuilder / ShapeBuilderErase, a plus in merge mode); a drag
keeps the mode it started in. The canvas re-hovers the tool when a
modifier changes, so the highlight follows Alt without a mouse move.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
17f66003cf