EditDemo.swift

//
//  ContentView.swift
//  EditDemo
//
//  Created by Ray Fix on 7/25/20.
//
import SwiftUI

// This is a hack!
func hideKeyboard() {
  UIApplication.shared.sendAction(#selector(UIResponder.resignFirstResponder), to: nil, from: nil, for: nil)
}

struct InlineTextEditor: View {
  @Binding var text: String
  var isValid: (String) -> Bool
  @State private var original: String = ""
  @State private var error = false

  var body: some View {
    Text(text)
      .hidden()
      .overlay(TextField("",  text: $text) { isEditing in
        original = text
        error = false
      } onCommit: {
        if isValid(text)  {
          error = false
        } else {
          withAnimation {
            error = true
          }
          text = original
        }
      }).shake(enable: error)
  }
}

extension View {
  func shake(enable: Bool) -> some View {
    self.modifier(ShakeEffect(enable))
      //.animation(enable ? .linear(duration: 0.25) : .none)
  }
}



struct ShakeEffect: GeometryEffect {

  init(_ activated: Bool) {
    x = activated ? 4 : 0
  }

  func effectValue(size: CGSize) -> ProjectionTransform {
    ProjectionTransform(CGAffineTransform(translationX: 5*sin(1.2 * .pi * x), y: 0) )
  }

  var x: CGFloat
  var animatableData: CGFloat {
    get { x }
    set { x = newValue }
  }
}


struct FolderView: View {

  @Binding var filename: String

  var body: some View {
    VStack {
      Image(systemName: "folder.fill")
        .resizable()
        .aspectRatio(contentMode: .fit)
        .foregroundColor(.blue)
        .frame(width: 70)
      InlineTextEditor(text: $filename) { input in
        !input.isEmpty && input.count < 10
      }
    }
  }
}


struct ContentView: View {

  @State private var offset = CGSize.zero
  @State private var start = CGSize.zero
  @State private var root = "Images"
  @State private var shaking = false

  var body: some View {
    VStack {
      TextField("", text: $root)
      Spacer()
    }
  }

//  var body: some View {
//
//    ZStack {
//
//      Color(.systemBackground).onTapGesture {
//        hideKeyboard()
//      }
//
//      VStack {
//        FolderView(filename: $root).shake(enable: shaking)
//          .offset(offset)
//          .gesture(
//            DragGesture(minimumDistance: 1, coordinateSpace: .local)
//              .onChanged { gesture in
//                offset = gesture.translation - start
//              }
//              .onEnded { _ in
//                start = -offset
//                withAnimation {
//                  shaking.toggle()
//                }
//              }
//          )
//      }
//    }
//  }
}


func +(lhs: CGSize, rhs: CGSize) -> CGSize {
  CGSize(width: lhs.width+rhs.width, height: lhs.height+rhs.height)
}

prefix func -(size: CGSize) -> CGSize {
  CGSize(width: -size.width, height: -size.height)
}

func -(lhs: CGSize, rhs: CGSize) -> CGSize {
  lhs + (-rhs)
}


struct ContentView_Previews: PreviewProvider {
  static var previews: some View {
    ContentView()
  }
}