initial commit
This commit is contained in:
Casper Zandbergen
commit
06886ac07b
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.DS_Store
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/.build
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/Packages
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/*.xcodeproj
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xcuserdata/
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// swift-tools-version:5.2
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// The swift-tools-version declares the minimum version of Swift required to build this package.
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import PackageDescription
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let package = Package(
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name: "ScrollViewProxy",
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products: [
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// Products define the executables and libraries produced by a package, and make them visible to other packages.
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.library(
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name: "ScrollViewProxy",
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targets: ["ScrollViewProxy"]),
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],
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dependencies: [
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// Dependencies declare other packages that this package depends on.
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// .package(url: /* package url */, from: "1.0.0"),
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.package(name: "Introspect", url: "https://github.com/timbersoftware/SwiftUI-Introspect.git", from: "0.1.0")
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],
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targets: [
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// Targets are the basic building blocks of a package. A target can define a module or a test suite.
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// Targets can depend on other targets in this package, and on products in packages which this package depends on.
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.target(
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name: "ScrollViewProxy",
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dependencies: ["Introspect"]),
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// .testTarget(
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// name: "ScrollViewProxyTests",
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// dependencies: ["ScrollViewProxy"]),
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]
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)
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# ScrollViewProxy
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Adds `ScrollViewReader` and `ScrollViewProxy` that help you scroll to locations in a ScrollView
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To get a ScrollViewProxy you can either use the conveinience init on ScrollView
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```swift
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ScrollView { proxy in
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...
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}
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```
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or add a ScrollViewReader to any View that creates a UIScrollView under the hood
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```swift
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List {
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ScrollViewReader { proxy in
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...
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}
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}
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```
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The ScrollViewProxy currently has two functions you can call
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```swift
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/// Scrolls to an edge or corner
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public func scrollTo(_ alignment: Alignment, animated: Bool = true)
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/// Scrolls the view with ID to an edge or corner
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public func scrollTo(_ id: ID, alignment: Alignment = .top, animated: Bool = true)
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```
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To use the scroll to ID function you have to add a view with that ID to the ScrollViewProxy
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```swift
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ScrollView { proxy in
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HStack { ... }
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.id("someId", scrollView: proxy)
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}
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```
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## Example
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Everything put together in an example
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```swift
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struct ScrollViewProxySimpleExample: View {
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@State var randomInt = Int.random(in: 0..<200)
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@State var proxy: ScrollViewProxy<Int>? = nil
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var body: some View {
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VStack {
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ScrollView { proxy in
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ForEach(0..<200) { index in
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VStack {
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Text("\(index)").font(.title)
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Spacer()
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}
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.padding()
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.id(index, scrollView: proxy)
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}.onAppear {
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self.proxy = proxy
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}
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}
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HStack {
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Button(action: {
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self.proxy?.scrollTo(self.randomInt, alignment: .center)
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self.randomInt = Int.random(in: 0..<200)
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}, label: {
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Text("Go to \(self.randomInt)")
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})
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Spacer()
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Button(action: { self.proxy?.scrollTo(.top) }, label: {
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Text("Top")
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})
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Spacer()
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Button(action: { self.proxy?.scrollTo(.center) }, label: {
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Text("Center")
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})
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Spacer()
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Button(action: { self.proxy?.scrollTo(.bottom) }, label: {
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Text("Bottom")
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})
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}
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}
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}
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}
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```
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@ -0,0 +1,133 @@
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// Created by Casper Zandbergen on 01/06/2020.
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// https://twitter.com/amzdme
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import SwiftUI
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import Introspect
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extension ScrollView {
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/// Creates a ScrollView with a ScrollViewReader
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public init<ID: Hashable, ProxyContent: View>(_ axes: Axis.Set = .vertical, showsIndicators: Bool = true, @ViewBuilder content: @escaping (ScrollViewProxy<ID>) -> ProxyContent) where Content == ScrollViewReader<ID, ProxyContent> {
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self.init(axes, showsIndicators: showsIndicators, content: {
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ScrollViewReader { content($0) }
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})
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}
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}
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extension View {
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/// Adds an ID to this view so you can scroll to it with `ScrollViewProxy.scrollTo(_:alignment:animated:)`
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public func id<ID: Hashable>(_ id: ID, scrollView proxy: ScrollViewProxy<ID>) -> some View {
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func save(geometry: GeometryProxy) -> some View {
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proxy.save(geometry: geometry, for: id)
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return Color.clear
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}
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return self.background(GeometryReader(content: save(geometry:)))
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}
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}
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public struct ScrollViewReader<ID: Hashable, Content: View>: View {
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private var content: (ScrollViewProxy<ID>) -> Content
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@State private var proxy = ScrollViewProxy<ID>()
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public init(@ViewBuilder content: @escaping (ScrollViewProxy<ID>) -> Content) {
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self.content = content
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}
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public var body: some View {
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content(proxy)
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.coordinateSpace(name: proxy.space)
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.introspectScrollView { self.proxy.coordinator.scrollView = $0 }
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}
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}
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public struct ScrollViewProxy<ID: Hashable> {
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fileprivate class Coordinator<ID: Hashable> {
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var frames = [ID: CGRect]()
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weak var scrollView: UIScrollView?
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}
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fileprivate var coordinator = Coordinator<ID>()
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fileprivate var space: UUID = UUID()
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fileprivate init() { }
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/// Scrolls to an edge or corner
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public func scrollTo(_ alignment: Alignment, animated: Bool = true) {
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guard let scrollView = coordinator.scrollView else { return }
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let contentRect = CGRect(origin: .zero, size: scrollView.contentSize)
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let visibleFrame = frame(contentRect, with: alignment)
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scrollView.scrollRectToVisible(visibleFrame, animated: animated)
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}
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/// Scrolls the view with ID to an edge or corner
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public func scrollTo(_ id: ID, alignment: Alignment = .top, animated: Bool = true) {
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guard let scrollView = coordinator.scrollView else { return }
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guard let cellFrame = coordinator.frames[id] else {
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return print("ID not found, make sure to add views with `.id(_:scrollView:)`")
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}
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let visibleFrame = frame(cellFrame, with: alignment)
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scrollView.scrollRectToVisible(visibleFrame, animated: animated)
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}
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private func frame(_ frame: CGRect, with alignment: Alignment) -> CGRect {
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guard let scrollView = coordinator.scrollView else { return frame }
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var visibleSize = scrollView.visibleSize
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visibleSize.width -= scrollView.adjustedContentInset.horizontal
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visibleSize.height -= scrollView.adjustedContentInset.vertical
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var origin = CGPoint.zero
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switch alignment {
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case .center:
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origin.x = frame.midX - visibleSize.width / 2
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origin.y = frame.midY - visibleSize.height / 2
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case .leading:
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origin.x = frame.minX
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origin.y = frame.midY - visibleSize.height / 2
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case .trailing:
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origin.x = frame.maxX - visibleSize.width
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origin.y = frame.midY - visibleSize.height / 2
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case .top:
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origin.x = frame.midX - visibleSize.width / 2
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origin.y = frame.minY
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case .bottom:
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origin.x = frame.midX - visibleSize.width / 2
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origin.y = frame.maxY - visibleSize.height
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case .topLeading:
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origin.x = frame.minX
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origin.y = frame.minY
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case .topTrailing:
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origin.x = frame.maxX - visibleSize.width
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origin.y = frame.minY
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case .bottomLeading:
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origin.x = frame.minX
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origin.y = frame.maxY - visibleSize.height
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case .bottomTrailing:
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origin.x = frame.maxX - visibleSize.width
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origin.y = frame.maxY - visibleSize.height
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default:
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fatalError("Not implemented")
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}
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origin.x = max(0, min(origin.x, scrollView.contentSize.width - visibleSize.width))
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origin.y = max(0, min(origin.y, scrollView.contentSize.height - visibleSize.height))
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return CGRect(origin: origin, size: visibleSize)
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}
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fileprivate func save(geometry: GeometryProxy, for id: ID) {
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coordinator.frames[id] = geometry.frame(in: .named(space))
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}
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}
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extension UIEdgeInsets {
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/// top + bottom
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var vertical: CGFloat {
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return top + bottom
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}
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/// left + right
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var horizontal: CGFloat {
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return left + right
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}
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}
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