mastodon-app-ufficiale-ipho.../MastodonSDK/Sources/MastodonUI/Vendor/ReorderableForEach.swift

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2022-10-21 13:12:44 +02:00
//
// ReorderableForEach.swift
//
//
// Created by MainasuK on 2022-5-23.
//
import SwiftUI
import UniformTypeIdentifiers
// Ref
// https://stackoverflow.com/a/68963988/3797903
struct ReorderableForEach<Content: View, Item: Identifiable & Equatable & NSItemProviderWriting & TypeIdentifiedItemProvider>: View {
@State var currentReorderItem: Item? = nil
@State var isCurrentReorderItemOutside: Bool = false
@Binding var items: [Item]
@ViewBuilder let content: (Binding<Item>) -> Content
var body: some View {
ForEach($items) { $item in
content($item)
.zIndex(currentReorderItem == item ? 1 : 0)
.onDrop(
of: [Item.typeIdentifier],
delegate: DropRelocateDelegate(
item: item,
items: $items,
current: $currentReorderItem,
isOutside: $isCurrentReorderItemOutside
)
)
.onDrag {
currentReorderItem = item
isCurrentReorderItemOutside = false
return NSItemProvider(object: item)
}
}
.onDrop(
of: [Item.typeIdentifier],
delegate: DropOutsideDelegate(
current: $currentReorderItem,
isOutside: $isCurrentReorderItemOutside
)
)
}
}
struct DropRelocateDelegate<Item: Equatable>: DropDelegate {
let item: Item
@Binding var items: [Item]
@Binding var current: Item?
@Binding var isOutside: Bool
func dropEntered(info: DropInfo) {
guard item != current, let current = current else { return }
guard let from = items.firstIndex(of: current), let to = items.firstIndex(of: item) else { return }
if items[to] != current {
withAnimation {
items.move(
fromOffsets: IndexSet(integer: from),
toOffset: to > from ? to + 1 : to
)
}
}
}
func dropUpdated(info: DropInfo) -> DropProposal? {
DropProposal(operation: .move)
}
func performDrop(info: DropInfo) -> Bool {
current = nil
isOutside = false
return true
}
}
struct DropOutsideDelegate<Item: Equatable>: DropDelegate {
@Binding var current: Item?
@Binding var isOutside: Bool
func dropEntered(info: DropInfo) {
isOutside = false
}
func dropExited(info: DropInfo) {
isOutside = true
}
func dropUpdated(info: DropInfo) -> DropProposal? {
return DropProposal(operation: .cancel)
}
func performDrop(info: DropInfo) -> Bool {
current = nil
isOutside = false
return false
}
}
public protocol TypeIdentifiedItemProvider {
static var typeIdentifier: String { get }
}