SwiftUI: Infinite Scrolling Horizontal ScrollView

Question

I need to create an infinite horizontal scrolling with ScrollView to scroll a panorama image. So I would like to make this scrolling infinite from both sides, is there any possible way to make it? I have searched maybe using ScrollViewReader can achieve this but no luck.

ScrollView(.horizontal, showsIndicators: false) {
    Image("panorama")
        .resizable()
        .scaledToFill()
} 

Answer 1

Actually for such prepared image it is enough to load it only once, and we need only to Image presenters for it (note: they do not copy memory, but use the same loaded image). Everything else is just about layout on the fly moving current of-screen item depending on drag direction to left or to the right of current one.

Tested with Xcode 13.4 / iOS 15.5

Main part of code:

struct PanoramaView: View {
    let image: UIImage

    private struct Item: Identifiable, Equatable {
        let id = UUID()
        var pos: CGFloat!
    }

    @State private var items = [Item(), Item()]

    // ...

    var body: some View {
        GeometryReader { gp in
            let centerY = gp.size.height / 2
            ForEach($items) { $item in
                Image(uiImage: image)
                    .resizable().aspectRatio(contentMode: .fill)
                    .position(x: item.pos ?? 0, y: centerY)
                    .offset(x: dragOffset)
            }
        }
        .background(GeometryReader {
            Color.clear.preference(key: ViewSizeKey.self,
                                   value: $0.frame(in: .local).size)
        })
        .onPreferenceChange(ViewSizeKey.self) {
            setupLayout($0)
        }
        .contentShape(Rectangle())
        .gesture(scrollGesture)
    }

and usage

    let panorama = UIImage(contentsOfFile: Bundle.main.path(forResource: "panorama", ofType: "jpeg")!)!
    var body: some View {
        PanoramaView(image: panorama)
            .frame(height: 300)   // to demo of dynamic internal layout
    }

Complete test code is here