将视图更改为刷卡手势上的一个圆圈，iOS，Swift

Question

我试图将刷卡手势（任何方向，快或慢）上的视图缩小为一个圆，类似于WhatsApp videoCall视图上的体验。查看下面的图片，了解我想要实现的目标。

我相信我需要使用滑动手势来实现这一点，我已经向我的videoView添加了滑动手势，我不确定接下来要做什么。

在viewDidLoad中我有以下

videoView.addGestureRecognizer(UISwipeGestureRecognizer(target: self, action: #selector(self.minimiseView))) 

我想我需要用手势位置？而且我还需要设置随着滑动而增加的拐角半径。请问一些人，请告诉我如何才能做到这一点？

func minimiseView(gesture: UISwipeGestureRecognizer){ 
     let location = gesture.location(in: self.view) 
    } 

Answer 1

你基本上要执行以下步骤：

1. 捕获起始姿势位置
2. 在刷卡，从原来的刷卡
3. 使用这个距离测量距离增加相机视角的圆角半径
   • 例如设置cornerRadius = distanceSwiped
4. 一旦拐角半径已经达到了一定的量（以及视图为圆形），再次捕获当前手势位置
5. 使用此值来开始跟踪运动，并用它来减少宽度视图的
6. 当视图是足够小驳回

这里是你如何完成这样的基本设置：

enum VideoDismissState { 
    case cornerRadiusChanging, sizeChanging, complete 
} 

var initialGesturePosition: CGPoint = .zero 
var maxCornerRadiusGesturePosition: CGPoint = .zero 
var dismissState: VideoDismissState = .complete 

func minimiseView(_ gesture: UISwipeGestureRecognizer) { 
    let location = gesture.location(in: videoView) 

    switch gesture.state { 
    case .began: 
     initialGesturePosition = gesture.location(in: videoView) 
     dismissState = .cornerRadiusChanging 
    case .changed: 
     let currentPosition = gesture.location(in: videoView) 

     switch dismissState { 
     case cornerRadiusChanging: 
      let swipeDistance = distance(between: initialGesturePosition, and: currentPosition) 
      // play around with this formula to see what feels right 
      videoView.layer.cornerRadius = swipeDistance/2 

      // at a certain point, switch to changing the size 
      if swipeDistance >= videoView.width/2 { 
       maxCornerRadiusGesturePosition = currentPosition 
       dismissState = .sizeChanging 
      } 
     case sizeChanging: 
      let swipeDistance = distance(between: maxCornerGesturePosition, and: currentPosition) 
      // again try different things to see what feels right here 
      let scaleFactor = 50/swipeDistance 

      videoView.layer.transform = CGAffineTransform(scaledX: scaleFactor, y: scaleFactor 

      if scaleFactor <= 0.2 { 
       dismissState = .complete 
      } 
     case complete: 
      // reset values 
      initialGesturePosition = .zero 
      maxCornerRadiusGesturePosition = .zero 

      // dismiss videoView 
      // for example: videoView.isHidden = true OR videoView.removeFromSuperview() 
     } 
    case .ended: 
     // if the gesture ends too soon you may want to animate the view back to full screen 
    } 
} 

/// Measure distance between two points 
func distance(between first: CGPoint, and second: CGPoint) -> CGFloat { 
    return sqrt((first.x - second.x)^2 + (first.y - second.y)^2) 
} 

这可能并不完全，因为我没有测试过，但基本的想法应该足以让你开始。