Interpolation

[gtokman]

Is it possible to have an API for interpolation like this with Motion?

@State var x = 0


@State var xOffset = AnimationWrapper(SpringAnimation<CGPoint>(value: x, input: [0, 1], output: [0, 300]))

// ...
Circle()
   .offset(x: yOffset)
Button(action: { x = 1 }) {
    Text("Tap me")
}
// ...

[b3ll]

SwiftUI integration is something I've played around with, but it can be tricky to get right.

In this case, would you assume that any modifications to x would start an animation? In the same light, what gets tricky is if then the animation itself is modifying x, that could also start another animation (or become recursive and crash lol). How would you want to disambiguate between running an animation and not?

What specifically in SwiftUI would you want to interpolate?

In the past, I've done something like putting a SpringAnimation into an observable object, and using that to animate changes to a value and then that value is updated within the SwiftUI view so you have changes to SwiftUI driven by the animator

[gtokman]

In this case, would you assume that any modifications to x would start an animation? In the same light, what gets tricky is if then the animation itself is modifying x, that could also start another animation (or become recursive and crash lol). How would you want to disambiguate between running an animation and not?

Agreed that it makes it tricky. Wonder if you can make a new @propertyWrapper instead. Like this would be the API:

struct AnimationScaleDemo: View {
    
    @Animated(in: [0, 1, 2], out: [1, 3, 1.5], onChange: { interpolatedValue in
        print("new", interpolatedValue) // 1.01, 1.02 .... 3
    })
    private var scale: CGFloat = 0
    
    var body: some View {
        VStack(spacing: 40) {
            Circle()
                .fill(.mint)
                .frame(width: 60, height: 60)
                .scaleEffect(scale)
            
            Button("Should Move to scale to 3") {
                scale = 1
            }
            
            Button("Should Move to scale to 1.5") {
                scale = 2
            }
            
            Button("Should Move to scale to 1") {
                scale = 0
            }
        }
        .font(.title2)
        .padding(60)
    }
}

What specifically in SwiftUI would you want to interpolate?

Things like offset, scale, opacity. I'd love to derive new values from the interpolation. Also, use it with scroll offset and much more. Having one variable that can drive gesture driven animations that are interuptable would be a big use case.