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RingSlider
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| import SwiftUI | |
| struct ContentView: View { | |
| @State var ratio: Double = 0 | |
| var body: some View { | |
| ZStack { | |
| Color(hue: 1, saturation: 0.3, brightness: 1) | |
| .hueRotation(.degrees(360 * ratio)) | |
| .ignoresSafeArea() | |
| RingSlider(ratio: $ratio) | |
| .frame(width: 300) | |
| Button("Reset") { reset() } | |
| .font(.title) | |
| .fontWeight(.bold) | |
| } | |
| .tint(.blue) | |
| } | |
| private func reset() { | |
| withAnimation { | |
| ratio = ratio.rounded(.toNearestOrEven) | |
| } | |
| } | |
| } | |
| struct RingSlider: View, Animatable { | |
| @Binding var ratio: Double | |
| var animatableData: Double | |
| init(ratio: Binding<Double>) { | |
| _ratio = ratio | |
| animatableData = ratio.wrappedValue | |
| } | |
| var body: some View { | |
| GeometryReader { geometry in | |
| let size = geometry.size | |
| let ringRadius = min(size.width, size.height) / 2 | |
| ZStack { | |
| // Ring | |
| let dotSize = ringRadius / 3 | |
| let lineWidth = 0.5 * dotSize | |
| Circle() | |
| .strokeBorder(lineWidth: lineWidth) | |
| .foregroundStyle(.tint) | |
| .frame(width: ringRadius * 2, height: ringRadius * 2) | |
| // Dot | |
| let r = ringRadius - lineWidth / 2 | |
| let t = 2 * .pi * animatableData - .pi / 2 | |
| Circle() | |
| .frame(width: dotSize, height: dotSize) | |
| .foregroundStyle(.white) | |
| .shadow(radius: 2) | |
| .offset(x: r * cos(t), y: r * sin(t)) | |
| } | |
| .gesture( | |
| DragGesture().onChanged { value in | |
| var location = value.location | |
| location.x -= ringRadius | |
| location.y -= ringRadius | |
| location.y *= -1 | |
| let t = atan2(location.x, location.y) / (2 * .pi) | |
| ratio = (t + 1).remainder(dividingBy: 1) | |
| } | |
| ) | |
| .frame(maxWidth: .infinity, maxHeight: .infinity) | |
| } | |
| } | |
| } | |
| #Preview { | |
| ContentView() | |
| } |
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