Currently, only the end handles of the line tool snap. It should be all
of them.
Line handles work kind of weirdly at the moment: instead of just storing
the positions, we store full `TLHandle` objects complete with IDs,
`canSnap`/`canBind` properties, etc. Currently, all the handles get
written to the store with `canSnap: false`, when really it should be up
to the shape util to decide which handles are snappable.
This diff replaces the current handles map (from arbitrary ID to
`TLHandle`) with just the data we need: a map from index to x/y. The
extra information that the `Editor` needs for `TLHandle` is hydrated at
runtime (with `canSnap` set to `true` this time!)
Fixes TLD-2200
This PR is part of a series - please don't merge it until the things
before it have landed!
1. #2827
2. #2831 (you are here)
3. #2793
4. #2841
5. #2845
### Change Type
- [x] `major` — Breaking change
[^1]: publishes a `patch` release, for devDependencies use `internal`
[^2]: will not publish a new version
### Test Plan
1. Create a funky line shape on tldraw.com
2. Paste it into staging and make sure it comes across ok
3. Make some funky line shape in staging - make sure you use dragging,
mid-point creation, and shift-clicking
- [x] Unit Tests
### Release Notes
- Simplify the contents of `TLLineShape.props.handles`
4bfea7649d