Tusker/Packages/MatchedGeometryPresentation/Sources/MatchedGeometryPresentation/MatchedGeometryModifiers.swift

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//
// MatchedGeometryModifiers.swift
// MatchGeom
//
// Created by Shadowfacts on 4/24/23.
//
import SwiftUI
extension View {
public func matchedGeometryPresentation<ID: Hashable, Presented: View>(id: Binding<ID?>, backgroundColor: UIColor, @ViewBuilder presenting: () -> Presented) -> some View {
self.modifier(MatchedGeometryPresentationModifier(id: id, backgroundColor: backgroundColor, presented: presenting()))
}
public func matchedGeometrySource<ID: Hashable, ID2: Hashable>(id: ID, presentationID: ID2) -> some View {
self.modifier(MatchedGeometrySourceModifier(id: AnyHashable(id), presentationID: AnyHashable(presentationID), matched: { AnyView(self) }))
}
public func matchedGeometryDestination<ID: Hashable>(id: ID) -> some View {
self.modifier(MatchedGeometryDestinationModifier(id: AnyHashable(id), matched: self))
}
}
private struct MatchedGeometryPresentationModifier<ID: Hashable, Presented: View>: ViewModifier {
@Binding var id: ID?
let backgroundColor: UIColor
let presented: Presented
@StateObject private var state = MatchedGeometryState()
private var isPresented: Binding<Bool> {
Binding {
id != nil
} set: {
if $0 {
fatalError()
} else {
id = nil
}
}
}
func body(content: Content) -> some View {
content
.environmentObject(state)
.backgroundPreferenceValue(MatchedGeometrySourcesKey.self, { sources in
Color.clear
.presentViewController(makeVC(allSources: sources), isPresented: isPresented)
})
}
private func makeVC(allSources: [SourceKey: (AnyView, CGRect)]) -> () -> UIViewController {
return {
// force unwrap is safe, this closure is only called when being presented so we must have an id
let id = AnyHashable(id!)
return MatchedGeometryViewController(
presentationID: id,
content: presented,
state: state,
backgroundColor: backgroundColor
)
}
}
}
private struct MatchedGeometrySourceModifier: ViewModifier {
let id: AnyHashable
let presentationID: AnyHashable
let matched: () -> AnyView
@EnvironmentObject private var state: MatchedGeometryState
func body(content: Content) -> some View {
content
.background(GeometryReader { proxy in
Color.clear
.preference(key: MatchedGeometryDestinationFrameKey.self, value: proxy.frame(in: .global))
.onPreferenceChange(MatchedGeometryDestinationFrameKey.self) { newValue in
if let newValue {
state.sources[SourceKey(presentationID: presentationID, matchedID: id)] = (matched, newValue)
}
}
})
.opacity(state.animating && state.presentationID == presentationID ? 0 : 1)
}
}
private struct MatchedGeometryDestinationModifier<Matched: View>: ViewModifier {
let id: AnyHashable
let matched: Matched
@EnvironmentObject private var state: MatchedGeometryState
func body(content: Content) -> some View {
content
.background(GeometryReader { proxy in
Color.clear
.preference(key: MatchedGeometryDestinationFrameKey.self, value: proxy.frame(in: .global))
.onPreferenceChange(MatchedGeometryDestinationFrameKey.self) { newValue in
if let newValue,
// ignore intermediate layouts that may happen while the dismiss animation is happening
state.mode != .dismissing {
state.destinations[id] = (AnyView(matched), newValue)
}
}
})
.opacity(state.animating ? 0 : 1)
}
}
private struct MatchedGeometryDestinationFrameKey: PreferenceKey {
static let defaultValue: CGRect? = nil
static func reduce(value: inout CGRect?, nextValue: () -> CGRect?) {
value = nextValue()
}
}
private struct MatchedGeometrySourcesKey: PreferenceKey {
static let defaultValue: [SourceKey: (AnyView, CGRect)] = [:]
static func reduce(value: inout Value, nextValue: () -> Value) {
value.merge(nextValue(), uniquingKeysWith: { _, new in new })
}
}
struct SourceKey: Hashable {
let presentationID: AnyHashable
let matchedID: AnyHashable
}