DraggableScaleableRotatableModifier.swift

struct DraggableScaleableRotatableModifier: ViewModifier {
  
  @State private var showingAlert = false
  
  @Binding var lastOffset: CGSize
  @Binding var lastRotation: Angle
  
  @Binding var offset: CGSize
  @Binding var scale: CGFloat
  @Binding var angle: Angle
  
  @State private var isHighlighted = false
  
  let onDuplicate: (() -> Void)?
  let onDelete: (() -> Void)?
  
  @GestureState private var twistAngle: Angle = .zero
  
  func body(content: Content) -> some View {
    
    let rotationGesture = RotationGesture(minimumAngleDelta: .degrees(10))
      .updating($twistAngle, body: { (value, state, _) in
        state = value
        DispatchQueue.main.async {
          isHighlighted = true
        }
      })
      .onEnded { value in
        DispatchQueue.main.async {
          self.angle += value
          isHighlighted = false
        }
      }
    
    let dragGesture = DragGesture()
      .onChanged({ (value) in
        DispatchQueue.main.async {
          self.offset = value.translation
          isHighlighted = true
        }
      })
      .onEnded({ (value) in
        DispatchQueue.main.async {
          self.lastOffset.width += value.translation.width
          self.lastOffset.height += value.translation.height
          self.offset = .zero
          isHighlighted = false
        }
      })
    
    let scaleGesture = MagnificationGesture()
      .onChanged { value in
        DispatchQueue.main.async {
          withAnimation(.easeInOut(duration: 0.2)) {
            self.scale = value.magnitude
            isHighlighted = true
          }
        }
      }
      .onEnded({ value in
        DispatchQueue.main.async {
          isHighlighted = false
        }
      })
    
    let gestures = rotationGesture
      .simultaneously(with: dragGesture)
      .simultaneously(with: scaleGesture)
    
    return content
      .rotationEffect(angle + twistAngle)
      .offset(x: offset.width + lastOffset.width, y: offset.height + lastOffset.height)
      .scaleEffect(scale)
      .gesture(gestures, including: .gesture)
      .background(
        Rectangle()
          .foregroundStyle(.clear)
          .padding()
          .padding()
          .padding()
          .background(Rectangle().foregroundStyle(Color.green.opacity(isHighlighted ? 0.10 : 0.0)))
          .rotationEffect(angle + twistAngle)
          .offset(x: offset.width + lastOffset.width, y: offset.height + lastOffset.height)
          .scaleEffect(scale)
          .gesture(gestures, including: .gesture)
      )
      .onTapGesture(count: 1, perform: {
        if onDelete != nil {
          showingAlert.toggle()
        }
      })
      .alert(isPresented: $showingAlert) {
        Alert(
          title: Text("Delete"),
          message: Text("Would you like to delete this?"),
          primaryButton: .destructive(Text("Delete")) {
            onDelete?()
          },
          secondaryButton: .cancel()
        )
      }
      .confirmationDialog("", isPresented: $showingAlert) {
        if onDuplicate != nil {
          Button("Duplicate") { onDuplicate?() }
        }
        Button("Delete", role: .destructive) { onDelete?() }
        Button("Cancel", role: .cancel) { }
      } message: {
        Text("Options")
      }
  }
}