Convert LayerCake.svelte lib to Svelte 5

[rgieseke]

As discussed in #329

[rgieseke]

On build I get

src/lib/LayerCake.svelte:204:28 This reference only captures the initial value of `yReverseValue`. Did you mean to reference it inside a closure instead?
https://svelte.dev/e/state_referenced_locally
202:   const _rNice = writable(rNice);
203:   const _xReverse = writable(xReverse);
204:   const _yReverse = writable(yReverseValue);
                                               ^
205:   const _zReverse = writable(zReverse);
206:   const _rReverse = writable(rReverse);

[rgieseke]

Maybe we can handle yReverseValue differently and then just use the derived store.

[mhkeller]

I've never liked how the LayerCake component has all of this code for x, y, z and r even if the user hasn't defined those. It would be nice if things were more dynamic where it looked at whether those accessors were set and then created properties as a result. I'm not sure if this will work with Svelte's reactivity but just putting it out there.

[mhkeller]

Maybe we can handle yReverseValue differently and then just use the derived store.

Ya that makes sense.

[rgieseke]

It would be nice if things were more dynamic where it looked at whether those accessors were set and then created properties as a result. I'm not sure if this will work with Svelte's reactivity but just putting it out there.

Not sure if it's possible to do everything without stores, but with or without stores maybe it's possible to be more dynamic with the context. You wrote earlier that it likely would look like chart.x etc. since it's not possibly anymore to destructure a context keys. Maybe that's an advantage for being more flexible.