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#if os(iOS)
import SwiftUI
import UIKit
struct NativeInteractiveImageScrollView<Content: View>: UIViewRepresentable {
@Binding var isZoomed: Bool
let contentIdentifier: String
let minimumZoomScale: CGFloat
let maximumZoomScale: CGFloat
let doubleTapZoomScale: CGFloat
let content: Content
init(
isZoomed: Binding<Bool>,
contentIdentifier: String,
minimumZoomScale: CGFloat,
maximumZoomScale: CGFloat,
doubleTapZoomScale: CGFloat,
@ViewBuilder content: () -> Content
) {
_isZoomed = isZoomed
self.contentIdentifier = contentIdentifier
self.minimumZoomScale = minimumZoomScale
self.maximumZoomScale = maximumZoomScale
self.doubleTapZoomScale = doubleTapZoomScale
self.content = content()
}
func makeUIView(context: Context) -> UIScrollView {
let scrollView = UIScrollView()
scrollView.delegate = context.coordinator
scrollView.minimumZoomScale = minimumZoomScale
scrollView.maximumZoomScale = maximumZoomScale
scrollView.zoomScale = minimumZoomScale
scrollView.bouncesZoom = true
scrollView.showsHorizontalScrollIndicator = false
scrollView.showsVerticalScrollIndicator = false
scrollView.contentInsetAdjustmentBehavior = .never
scrollView.decelerationRate = .fast
let hostingController = UIHostingController(rootView: content)
hostingController.view.backgroundColor = .clear
hostingController.view.translatesAutoresizingMaskIntoConstraints = false
scrollView.addSubview(hostingController.view)
NSLayoutConstraint.activate([
hostingController.view.leadingAnchor.constraint(
equalTo: scrollView.contentLayoutGuide.leadingAnchor
),
hostingController.view.trailingAnchor.constraint(
equalTo: scrollView.contentLayoutGuide.trailingAnchor
),
hostingController.view.topAnchor.constraint(
equalTo: scrollView.contentLayoutGuide.topAnchor
),
hostingController.view.bottomAnchor.constraint(
equalTo: scrollView.contentLayoutGuide.bottomAnchor
),
hostingController.view.widthAnchor.constraint(
equalTo: scrollView.frameLayoutGuide.widthAnchor
),
hostingController.view.heightAnchor.constraint(
equalTo: scrollView.frameLayoutGuide.heightAnchor
),
])
let doubleTapGestureRecognizer = UITapGestureRecognizer(
target: context.coordinator,
action: #selector(Coordinator.handleDoubleTapGesture(_:))
)
doubleTapGestureRecognizer.numberOfTapsRequired = 2
scrollView.addGestureRecognizer(doubleTapGestureRecognizer)
context.coordinator.hostingController = hostingController
context.coordinator.hostedView = hostingController.view
context.coordinator.latestContentIdentifier = contentIdentifier
context.coordinator.updateZoomState(for: scrollView)
context.coordinator.recenterContent(in: scrollView)
return scrollView
}
func updateUIView(_ scrollView: UIScrollView, context: Context) {
context.coordinator.parent = self
context.coordinator.hostingController?.rootView = content
if context.coordinator.latestContentIdentifier != contentIdentifier {
context.coordinator.latestContentIdentifier = contentIdentifier
scrollView.setZoomScale(minimumZoomScale, animated: false)
scrollView.contentOffset = .zero
}
context.coordinator.recenterContent(in: scrollView)
context.coordinator.updateZoomState(for: scrollView)
}
func makeCoordinator() -> Coordinator {
Coordinator(parent: self)
}
final class Coordinator: NSObject, UIScrollViewDelegate {
var parent: NativeInteractiveImageScrollView
var hostingController: UIHostingController<Content>?
weak var hostedView: UIView?
var latestContentIdentifier: String?
init(parent: NativeInteractiveImageScrollView) {
self.parent = parent
}
func viewForZooming(in _: UIScrollView) -> UIView? {
hostedView
}
func scrollViewDidZoom(_ scrollView: UIScrollView) {
recenterContent(in: scrollView)
updateZoomState(for: scrollView)
}
@objc
func handleDoubleTapGesture(_ recognizer: UITapGestureRecognizer) {
guard let scrollView = recognizer.view as? UIScrollView else { return }
let minimumZoomScale = scrollView.minimumZoomScale
let maximumZoomScale = scrollView.maximumZoomScale
let targetZoomScale = min(parent.doubleTapZoomScale, maximumZoomScale)
if scrollView.zoomScale > minimumZoomScale + 0.01 {
scrollView.setZoomScale(minimumZoomScale, animated: true)
return
}
guard let hostedView else { return }
let tapLocation = recognizer.location(in: hostedView)
let zoomRectangle = zoomRectangle(
for: targetZoomScale,
centeredAt: tapLocation,
in: scrollView
)
scrollView.zoom(to: zoomRectangle, animated: true)
}
func recenterContent(in scrollView: UIScrollView) {
let horizontalInset = max((scrollView.bounds.width - scrollView.contentSize.width) / 2, 0)
let verticalInset = max((scrollView.bounds.height - scrollView.contentSize.height) / 2, 0)
scrollView.contentInset = UIEdgeInsets(
top: verticalInset,
left: horizontalInset,
bottom: verticalInset,
right: horizontalInset
)
}
func updateZoomState(for scrollView: UIScrollView) {
let isCurrentlyZoomed = scrollView.zoomScale > scrollView.minimumZoomScale + 0.01
if parent.isZoomed != isCurrentlyZoomed {
DispatchQueue.main.async {
self.parent.isZoomed = isCurrentlyZoomed
}
}
}
private func zoomRectangle(
for targetZoomScale: CGFloat,
centeredAt tapLocation: CGPoint,
in scrollView: UIScrollView
) -> CGRect {
let rectangleWidth = scrollView.bounds.width / targetZoomScale
let rectangleHeight = scrollView.bounds.height / targetZoomScale
let horizontalOrigin = tapLocation.x - (rectangleWidth / 2)
let verticalOrigin = tapLocation.y - (rectangleHeight / 2)
return CGRect(
x: horizontalOrigin,
y: verticalOrigin,
width: rectangleWidth,
height: rectangleHeight
)
}
}
}
#endif
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