IceCubesApp/Packages/MediaUI/Sources/MediaUI/MediaUIZoomableContainer.swift
Thomas Ricouard 3e3c69c41c format
2023-11-01 18:58:44 +01:00

107 lines
3.6 KiB
Swift

import SwiftUI
import UIKit
// ref: https://stackoverflow.com/questions/74238414/is-there-an-easy-way-to-pinch-to-zoom-and-drag-any-view-in-swiftui
private let maxAllowedScale = 4.0
@MainActor
struct MediaUIZoomableContainer<Content: View>: View {
let content: Content
@State private var currentScale: CGFloat = 1.0
@State private var tapLocation: CGPoint = .zero
init(@ViewBuilder content: () -> Content) {
self.content = content()
}
func doubleTapAction(location: CGPoint) {
tapLocation = location
currentScale = currentScale == 1.0 ? maxAllowedScale : 1.0
}
var body: some View {
ZoomableScrollView(scale: $currentScale, tapLocation: $tapLocation) {
content
}
.onTapGesture(count: 2, perform: doubleTapAction)
}
fileprivate struct ZoomableScrollView<ScollContent: View>: UIViewRepresentable {
private var content: ScollContent
@Binding private var currentScale: CGFloat
@Binding private var tapLocation: CGPoint
init(scale: Binding<CGFloat>, tapLocation: Binding<CGPoint>, @ViewBuilder content: () -> ScollContent) {
_currentScale = scale
_tapLocation = tapLocation
self.content = content()
}
func makeUIView(context: Context) -> UIScrollView {
let scrollView = UIScrollView()
scrollView.backgroundColor = .clear
scrollView.delegate = context.coordinator
scrollView.maximumZoomScale = maxAllowedScale
scrollView.minimumZoomScale = 1
scrollView.bouncesZoom = true
scrollView.showsHorizontalScrollIndicator = false
scrollView.showsVerticalScrollIndicator = false
scrollView.clipsToBounds = false
scrollView.backgroundColor = .clear
let hostedView = context.coordinator.hostingController.view!
hostedView.translatesAutoresizingMaskIntoConstraints = true
hostedView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
hostedView.frame = scrollView.bounds
hostedView.backgroundColor = .clear
scrollView.addSubview(hostedView)
return scrollView
}
func makeCoordinator() -> Coordinator {
Coordinator(hostingController: UIHostingController(rootView: content), scale: $currentScale)
}
func updateUIView(_ uiView: UIScrollView, context: Context) {
context.coordinator.hostingController.rootView = content
if uiView.zoomScale > uiView.minimumZoomScale { // Scale out
uiView.setZoomScale(currentScale, animated: true)
} else if tapLocation != .zero { // Scale in to a specific point
uiView.zoom(to: zoomRect(for: uiView, scale: uiView.maximumZoomScale, center: tapLocation), animated: true)
DispatchQueue.main.async { tapLocation = .zero }
}
}
@MainActor func zoomRect(for scrollView: UIScrollView, scale: CGFloat, center: CGPoint) -> CGRect {
let scrollViewSize = scrollView.bounds.size
let width = scrollViewSize.width / scale
let height = scrollViewSize.height / scale
let x = center.x - (width / 2.0)
let y = center.y - (height / 2.0)
return CGRect(x: x, y: y, width: width, height: height)
}
class Coordinator: NSObject, UIScrollViewDelegate {
var hostingController: UIHostingController<ScollContent>
@Binding var currentScale: CGFloat
init(hostingController: UIHostingController<ScollContent>, scale: Binding<CGFloat>) {
self.hostingController = hostingController
_currentScale = scale
}
func viewForZooming(in _: UIScrollView) -> UIView? {
hostingController.view
}
func scrollViewDidEndZooming(_: UIScrollView, with _: UIView?, atScale scale: CGFloat) {
currentScale = scale
}
}
}
}