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import SwiftUI
struct AsyncImageWithPreview<Placeholder: View>: View {
var url: URL?
@Binding var loadingState: PostLoadingState
var finalLoadingState: PostLoadingState
var postURL: URL?
let placeholder: () -> Placeholder
@State private var currentScale: CGFloat = 1.0
@State private var finalScale: CGFloat = 1.0
@State private var currentOffset: CGSize = .zero
@State private var finalOffset: CGSize = .zero
init(
url: URL?,
loadingStage: Binding<PostLoadingState>,
finalLoadingState: PostLoadingState = .loadingFile,
postURL: URL? = nil,
@ViewBuilder placeholder: @escaping () -> Placeholder = {
GeometryReader { geometry in
ProgressView()
.frame(width: geometry.size.width, height: geometry.size.height)
.position(x: geometry.size.width / 2, y: geometry.size.height / 2)
.padding()
}
}
) {
self.url = url
_loadingState = loadingStage
self.finalLoadingState = finalLoadingState
self.postURL = postURL
self.placeholder = placeholder
}
var body: some View {
GeometryReader { geometry in
AsyncImage(url: url) { image in
image
.resizable()
.scaledToFit()
.onAppear {
loadingState = finalLoadingState
}
.scaleEffect(finalScale * currentScale)
.offset(
x: finalOffset.width + currentOffset.width,
y: finalOffset.height + currentOffset.height
)
.frame(width: geometry.size.width, height: geometry.size.height)
.position(x: geometry.size.width / 2, y: geometry.size.height / 2)
.gesture(
DragGesture()
.onChanged { value in
let translation = value.translation
let newOffset = CGSize(
width: finalOffset.width + translation.width,
height: finalOffset.height + translation.height
)
let scale = finalScale * currentScale
let imageWidth = geometry.size.width * scale
let imageHeight = geometry.size.height * scale
let maxX = max((imageWidth - geometry.size.width) / 2, 0)
let maxY = max((imageHeight - geometry.size.height) / 2, 0)
let clampedX = min(max(newOffset.width, -maxX), maxX)
let clampedY = min(max(newOffset.height, -maxY), maxY)
currentOffset = CGSize(
width: clampedX - finalOffset.width,
height: clampedY - finalOffset.height
)
}
.onEnded { value in
let translation = value.translation
var newOffset = CGSize(
width: finalOffset.width + translation.width,
height: finalOffset.height + translation.height
)
let scale = finalScale * currentScale
let imageWidth = geometry.size.width * scale
let imageHeight = geometry.size.height * scale
let maxX = max((imageWidth - geometry.size.width) / 2, 0)
let maxY = max((imageHeight - geometry.size.height) / 2, 0)
newOffset.width = min(max(newOffset.width, -maxX), maxX)
newOffset.height = min(max(newOffset.height, -maxY), maxY)
finalOffset = newOffset
currentOffset = .zero
}
)
.simultaneousGesture(
MagnificationGesture()
.onChanged { value in
currentScale = value
}
.onEnded { _ in
finalScale *= currentScale
currentScale = 1.0
let scale = finalScale
let imageWidth = geometry.size.width * scale
let imageHeight = geometry.size.height * scale
let maxX = max((imageWidth - geometry.size.width) / 2, 0)
let maxY = max((imageHeight - geometry.size.height) / 2, 0)
finalOffset.width = min(max(finalOffset.width, -maxX), maxX)
finalOffset.height = min(max(finalOffset.height, -maxY), maxY)
}
)
.highPriorityGesture(
TapGesture(count: 2)
.onEnded {
withAnimation {
finalScale = 1.0
currentScale = 1.0
finalOffset = .zero
currentOffset = .zero
}
}
)
.contextMenu {
#if os(iOS)
Button {
guard let url else { return }
URLSession.shared.dataTask(with: url) { data, _, _ in
guard let data, let uiImage = UIImage(data: data) else { return }
UIImageWriteToSavedPhotosAlbum(uiImage, nil, nil, nil)
}.resume()
} label: {
Label("Save Image", systemImage: "square.and.arrow.down")
}
#endif
#if os(iOS)
Button {
let activityViewController = UIActivityViewController(
activityItems: [url ?? URL(string: "")!], applicationActivities: nil)
UIApplication.shared.windows.first?.rootViewController?.present(
activityViewController, animated: true)
} label: {
Label("Share Image", systemImage: "square.and.arrow.up")
}
#endif
if let url = postURL {
Button {
#if os(iOS)
UIApplication.shared.open(url)
#else
NSWorkspace.shared.open(url)
#endif
} label: {
Label("Open in Safari", systemImage: "safari")
}
}
}
} placeholder: {
placeholder()
.onAppear {
loadingState = .loadingPreview
}
}
}
}
}
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