CancelableTapGestureRecognizer.swift

//
//  CancelableTapGestureRecognizer.swift
//
//  Created by Wanbok Choi on 2017. 5. 4..
//

import UIKit.UIGestureRecognizerSubclass

import RxSwift
import RxCocoa
import RxGesture

final class SensitiveTapGestureRecognizer: UIGestureRecognizer {
  let delta: CGFloat = 4
  var position: CGPoint?

  func distance(a: CGPoint, b: CGPoint) -> CGFloat {
    let xDist = a.x - b.x
    let yDist = a.y - b.y
    return CGFloat(sqrt((xDist * xDist) + (yDist * yDist)))
  }
  
  override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent) {
    self.position = touches.first?.location(in: self.view)
  }
  override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
    guard let currentPosition = touches.first?.location(in: self.view),
      let beginingPosition = self.position,
      currentPosition ~ beginingPosition < self.delta
      else {
        self.state = .failed
        return
      }
  }
  override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent) {
    defer { self.position = nil }
    self.state = .cancelled
  }
  override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent) {
    defer { self.position = nil }
    guard self.state == .possible else { return }
    self.state = .recognized
  }
}

struct SensitiveTapGestureRecognizerFactory: GestureRecognizerFactory {
  typealias Gesture = SensitiveTapGestureRecognizer
  let configuration: (SensitiveTapGestureRecognizer) -> Void
  
  /**
   Initialiaze a `GestureRecognizerFactory` for `UITapGestureRecognizer`
   - parameter numberOfTouchesRequired: The number of fingers required to match
   - parameter numberOfTapsRequired: The number of taps required to match
   - parameter configuration: A closure that allows to fully configure the gesture recognizer
   */
  init(){
    self.configuration = { gesture in }
  }
}

extension Reactive where Base: UIView {
  
  var sensitiveTapGesture: ControlEvent<SensitiveTapGestureRecognizer> {
    return gesture(SensitiveTapGestureRecognizerFactory())
  }
}