SwiftUI 我想使用 simultaneousGesture 但也想使用孤立的手势

Question

我想同时使用 RotationGesture 和 MagnificationGesture。但是我也单独使用这些手势。这是我的代码。

struct TmpView10: View {
    @State private var magnify: CGFloat = 1
    @State private var lastMagnify: CGFloat = 1
    @State private var angle: Angle = .degrees(.zero)
    @State private var lastAngle: Angle = .degrees(.zero)
    
    var body: some View {
        VStack () {
            ZStack () {
                Image("someImage")
                    .resizable()
                    .aspectRatio(contentMode: .fit)
                    .scaleEffect(self.magnify)
                    .rotationEffect(self.angle)
                    .gesture(RotationGesture()
                        .onChanged{ angle in
                            self.angle = angle + self.lastAngle
                        }
                        .onEnded { angle in
                            self.lastAngle = self.angle
                        }
                    )
                    .simultaneousGesture(MagnificationGesture(minimumScaleDelta: 0.5)
                        .onChanged{ v in
                            let delta = v / self.lastMagnify
                            self.lastMagnify = v
                            self.magnify *= delta
                        }
                        .onEnded{ v in
                            self.lastMagnify = 1
                        }
                    )
                    .clipShape(Circle())
                    .overlay(
                        Circle().stroke(LinearGradient(gradient: Gradient(colors: [.yellow, .red, .purple]), startPoint: .bottomLeading, endPoint: .topTrailing), lineWidth: 5))
            }
        }
    }
}

通过这段代码，我可以同时使用两个手势。但是一旦我只旋转图像，MagnificationGesture 就会停止工作。有什么方法可以同时使用 simultaneousGesture 和单个手势吗？

Answer 1

通过使用 .updating GestureState 围绕 minimumScaleDelta 的使用进行编码似乎可以解决问题。

struct ContentView: View {
@State private var lastMagnify: CGFloat = 1
@State private var lastAngle: Angle = .degrees(.zero)
@GestureState private var magnification: (active: Bool, factor: CGFloat) = (active: false, CGFloat(1))
@GestureState private var angle: Angle = .degrees(.zero)

var rotateAndMagnifyGesture: some Gesture {
    let rotate = RotationGesture()
        .updating($angle) { (newAngle, gestureState, _) in
            gestureState = newAngle
        }
        .onEnded { angle in
            lastAngle += angle
        }
    let magnify = MagnificationGesture()
        .updating($magnification) { (value, gestureState, _) in
            gestureState.factor = value
            
            let delta = value / lastMagnify
            if abs(1 - delta) > 0.3 {
                gestureState.active = true
            }
        }
        .onEnded { value in
            lastMagnify *= value
        }
    return rotate.simultaneously(with: magnify)
}

var body: some View {
    VStack () {
        ZStack () {
            Image(systemName: "diamond")
                .resizable()
                .rotationEffect((lastAngle + angle))
                .scaleEffect(magnification.active ? (magnification.factor * lastMagnify) : lastMagnify)
                .aspectRatio(contentMode: .fit)
                .gesture(rotateAndMagnifyGesture)
                .clipShape(Circle())
                .overlay(
                    Circle().stroke(LinearGradient(gradient: Gradient(colors: [.yellow, .red, .purple]), startPoint: .bottomLeading, endPoint: .topTrailing), lineWidth: 5))
        }
    }
}