feat: enable SpringRef.set to be called with a function (#2069)

.changeset/strange-falcons-confess.md

@@ -0,0 +1,16 @@
+---
+'@react-spring/core': minor
+'@react-spring/animated': minor
+'@react-spring/parallax': minor
+'@react-spring/rafz': minor
+'react-spring': minor
+'@react-spring/shared': minor
+'@react-spring/types': minor
+'@react-spring/konva': minor
+'@react-spring/native': minor
+'@react-spring/three': minor
+'@react-spring/web': minor
+'@react-spring/zdog': minor
+---
+
+feat: add function to SpringRef.set

docs/app/routes/docs/advanced/spring-ref.mdx

@@ -110,10 +110,12 @@ resume(keys?: OneOrMore<string>): this
 
 ### Set
 
-Update the state of each controller without animating.
+Update the state of each controller without animating. Accepts either a partial state object or a
+function that returns a partial state object.
 
 ```ts
 set(values: Partial<State>): void
+set(values: (index: number, ctrl: Controller<State>) => Partial<State>): void
 ```
 
 ### Start

packages/core/src/SpringRef.ts

@@ -35,6 +35,8 @@ export interface SpringRef<State extends Lookup = Lookup> {
 
  /** Update the state of each controller without animating. */
  set(values: Partial<State>): void
+ /** Update the state of each controller without animating based on their passed state. */
+ set(values: (index: number, ctrl: Controller<State>) => Partial<State>): void
 
  /** Start the queued animations of each controller. */
  start(): AsyncResult<Controller<State>>[]
@@ -126,8 +128,17 @@ export const SpringRef = <
  }
 
  /** Update the state of each controller without animating. */
- SpringRef.set = function (values: Partial<State>) {
- each(current, ctrl => ctrl.set(values))
+ SpringRef.set = function (
+ values:
+ | Partial<State>
+ | ((i: number, ctrl: Controller<State>) => Partial<State>)
+ ) {
+ each(current, (ctrl, i) => {
+ const update = is.fun(values) ? values(i, ctrl) : values
+ if (update) {
+ ctrl.set(update)
+ }
+ })
  }
 
  SpringRef.start = function (props?: object | ControllerUpdateFn<State>) {
@@ -163,7 +174,7 @@ export const SpringRef = <
  arg: ControllerUpdate<State> | ControllerUpdateFn<State>,
  ctrl: Controller<State>,
  index: number
- ): ControllerUpdate<State> | Falsy {
+ ) {
  return is.fun(arg) ? arg(index, ctrl) : arg
  }