SwiftUI: Infinite Scrolling Horizontal ScrollView - ios

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

Answer 2

You can put 3 identical panorama images next to each other (to be able to scroll over the edges) and add a custom DragGesture, that basically jumps back to the relative position of the middle image.
This image is a bad example, obviously it will work better with a real 360° image ;)
EDIT:
now with predicted end location + animation and 5 images.
struct ContentView: View {
#State private var dragOffset = CGFloat.zero
#State private var offset = CGFloat.zero
let imageWidth: CGFloat = 500
var body: some View {
HStack(spacing: 0) {
ForEach(0..<5) { _ in
Image("image")
.resizable()
.frame(width: imageWidth)
}
}
.offset(x: offset + dragOffset)
.gesture(
DragGesture()
.onChanged({ value in
dragOffset = value.translation.width
})
.onEnded({ value in
withAnimation(.easeOut) {
dragOffset = value.predictedEndTranslation.width
}
offset = (offset + dragOffset).remainder(dividingBy: imageWidth)
dragOffset = 0
})
)
}
}