ryanashcraft · August 9, 2020 20:17 · Aug 9, 2020
diff --git a/LyricsDemoApp.swift b/LyricsDemoApp.swift
@@ -0,0 +1,225 @@
+import SwiftUI
+
+// Models
+
+enum Lyric {
+    case line(String)
+    case pause(TimeInterval)
+}
+
+class ScrollToModel: ObservableObject {
+    @Published var activeLyricIndex: Int = 0
+
+    var lyrics: [Lyric] = [
+        .pause(2),
+        .line("Now and then I think of when we were together"),
+        .line("Like when you said you felt so happy you could die"),
+        .line("Told myself that you were right for me"),
+        .line("But felt so lonely in your company"),
+        .line("But that was love and it's an ache I still remember"),
+        .line("You can get addicted to a certain kind of sadness"),
+        .line("Like resignation to the end, always the end"),
+        .line("So when we found that we could not make sense"),
+        .line("Well, you said that we would still be friends"),
+        .line("But I'll admit that I was glad that it was over"),
+        .line("But you didn't have to cut me off"),
+        .line("Make out like it never happened and that we were nothing"),
+        .line("And I don't even need your love"),
+        .line("But you treat me like a stranger and that feels so rough"),
+        .line("No, you didn't have to stoop so low"),
+        .line("Have your friends collect your records and then change your number"),
+        .line("I guess that I don't need that though"),
+        .line("Now you're just somebody that I used to know"),
+        .line("Now you're just somebody that I used to know"),
+        .line("Now you're just somebody that I used to know"),
+        .line("Now and then I think of all the times you screwed me over"),
+        .line("But had me believing it was always something that I'd done"),
+        .line("But I don't wanna live that way"),
+        .line("Reading into every word you say"),
+        .line("You said that you could let it go"),
+        .line("And I wouldn't catch you hung up on somebody that you used to know"),
+        .line("But you didn't have to cut me off"),
+        .line("Make out like it never happened and that we were nothing"),
+        .line("And I don't even need your love"),
+        .line("But you treat me like a stranger and that feels so rough"),
+        .line("No, you didn't have to stoop so low"),
+        .line("Have your friends collect your records and then change your number"),
+        .line("I guess that I don't need that though"),
+        .line("Now you're just somebody that I used to know"),
+        .line("Somebody (I used to know)"),
+        .line("Somebody (Now you're just somebody that I used to know)"),
+        .line("Somebody (I used to know)"),
+        .line("Somebody (Now you're just somebody that I used to know)"),
+        .line("I used to know"),
+        .line("That I used to know"),
+        .line("I used to know"),
+        .line("Somebody"),
+    ]
+
+    func lyric(for index: Int) -> Lyric? {
+        if index >= 0 && index < lyrics.count {
+            return lyrics[index]
+        }
+
+        return nil
+    }
+
+    func lyricDuration(for lyric: Lyric) -> TimeInterval {
+        switch lyric {
+        case .line(let text):
+            let wordCount = text.split(separator: " ").count
+            var duration = TimeInterval(wordCount) * 0.4
+
+            if wordCount < 5 {
+                duration += TimeInterval.random(in: 0...8)
+            }
+
+            return duration
+        case .pause(let pauseDuration):
+            return pauseDuration
+        }
+    }
+
+    func scheduleNextLyric() {
+        guard let currentLyric = lyric(for: activeLyricIndex) else {
+            return
+        }
+
+        let duration = lyricDuration(for: currentLyric)
+
+        let timer = Timer(timeInterval: duration, repeats: false) { _ in
+            self.activeLyricIndex += 1
+
+            self.scheduleNextLyric()
+        }
+
+        RunLoop.main.add(timer, forMode: .default)
+    }
+
+    func play() {
+        scheduleNextLyric()
+    }
+}
+
+// Main content
+
+struct ContentView: View {
+    @StateObject var model = ScrollToModel()
+
+    var body: some View {
+        ScrollView {
+            ScrollViewReader { scrollProxy in
+                LazyVStack(alignment: .leading, spacing: 0) {
+                    ForEach(Array(model.lyrics.enumerated()), id: \.0) { i, lyric in
+                        Group {
+                            switch lyric {
+                            case .line(let lyricText):
+                                Text(lyricText)
+                                    .multilineTextAlignment(.leading)
+                                    .font(Font.title.bold())
+                                    .frame(maxWidth: .infinity, alignment: .leading)
+                            case .pause:
+                                EllipsisSpinner(size: .large)
+                                    .scaleEffect(model.activeLyricIndex == i ? 1 : 0.5, anchor: .center)
+                                    .opacity(model.activeLyricIndex == i ? 1 : 0)
+                                    .animation(Animation.easeIn(duration: 0.4))
+                            }
+                        }
+                            .foregroundColor(Color(hue: 0.12, saturation: 0.32, brightness: 0.93))
+                            .opacity(model.activeLyricIndex == i ? 1 : 0.5)
+                            .blur(radius: model.activeLyricIndex == i ? 0 : 2)
+                            .animation(.default)
+                        .padding()
+                    }
+                }.onReceive(model.$activeLyricIndex) { activeLyricIndex in
+                    withAnimation {
+                        scrollProxy.scrollTo(activeLyricIndex, anchor: .center)
+                    }
+                }
+            }
+        }
+        .background(
+            Image("gotye")
+                .resizable()
+                .scaledToFill()
+                .scaleEffect(6, anchor: .center)
+                .transformEffect(CGAffineTransform(translationX: -100, y: -100))
+                .blur(radius: 30)
+                .blendMode(.multiply)
+                .background(
+                    Color(hue: 0.07, saturation: 0.70, brightness: 0.71)
+                )
+                .edgesIgnoringSafeArea(.all)
+        )
+        .onAppear {
+            model.play()
+        }
+    }
+}
+
+// Ellipsis spinner
+
+struct EllipsisSpinner: View {
+    enum Size {
+        case small
+        case large
+
+        var circleSize: CGFloat {
+            switch self {
+            case .small:
+                return 4
+            case .large:
+                return 14
+            }
+        }
+
+        var spacing: CGFloat {
+            switch self {
+            case .small:
+                return 3
+            case .large:
+                return 6
+            }
+        }
+    }
+
+    let size: Size
+
+    @State private var counter: Int = 0
+    @State private var isScaled: Bool = false
+    @State private var timer = Timer.publish(every: 1, on: .main, in: .common).autoconnect()
+
+    var body: some View {
+        HStack(alignment: .center, spacing: self.size.spacing) {
+            ForEach(0 ... 2, id: \.self) { i in
+                Circle()
+                    .frame(
+                        width: self.size.circleSize,
+                        height: self.size.circleSize
+                    )
+                    .opacity(self.counter % 3 == i ? 1.0 : 0.3)
+                    .animation(.default)
+            }
+        }
+        .scaleEffect(isScaled ? 1.1 : 1, anchor: .center)
+        .animation(Animation.easeInOut(duration: 3).repeatForever(autoreverses: true))
+        .onReceive(timer) { _ in
+            self.counter += 1
+        }
+        .onAppear {
+            self.isScaled.toggle()
+        }
+    }
+}
+
+// App
+
+@main
+struct LyricsDemoApp: App {
+    var body: some Scene {
+        WindowGroup {
+            ContentView()
+                .preferredColorScheme(.dark)
+        }
+    }
+}