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swift - 如何从特定锚点旋转图像

问题描述

我想在这段代码中旋转一个图像是 pic1。我在下面放了一张我正在寻找的图片。我不想将整个图像从矩形的左下角旋转 90 度。您可以在绿色圆圈中具体看到我在说什么。旋转应在按钮功能中进行。

import UIKit

class ViewController: UIViewController {


var pic1 = UIImageView()

var rot = UIButton()


override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view.

    pic1.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(pic1)

    rot.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(rot)
    rot.backgroundColor = .blue


    pic1.image = UIImage(named: "badMan.png")

    NSLayoutConstraint.activate(



        [

            pic1.heightAnchor.constraint(equalTo: view.heightAnchor, multiplier: 0.50),
            pic1.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: 1),
            pic1.topAnchor.constraint(equalTo: view.topAnchor),
            pic1.leadingAnchor.constraint(equalTo: view.leadingAnchor),

            rot.heightAnchor.constraint(equalTo: view.heightAnchor, multiplier: 0.50),
            rot.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: 1),
            rot.topAnchor.constraint(equalTo: pic1.bottomAnchor),
            rot.leadingAnchor.constraint(equalTo: view.leadingAnchor),





    ])


    self.view.addSubview(pic2)

    rot.addTarget(self, action: #selector(roate), for: .touchDown)
}


@objc func roate(){



}
}

在此处输入图像描述

标签： swiftrotationcgpointanchorpoint

解决方案

您可以扩展 uiview 来设置锚点：

extension UIView{
    func setAnchorPoint(anchorPoint: CGPoint) {

        var newPoint = CGPoint(x: self.bounds.size.width * anchorPoint.x, y: self.bounds.size.height * anchorPoint.y)
        var oldPoint = CGPoint(x: self.bounds.size.width * self.layer.anchorPoint.x, y: self.bounds.size.height * self.layer.anchorPoint.y)

        newPoint = newPoint.applying(self.transform)
        oldPoint = oldPoint.applying(self.transform)

        var position : CGPoint = self.layer.position

        position.x -= oldPoint.x
        position.x += newPoint.x;

        position.y -= oldPoint.y;
        position.y += newPoint.y;

        self.layer.position = position;
        self.layer.anchorPoint = anchorPoint;
    }
}

然后在 viewDidLoad 中设置锚点：

// set anchor point, below code will set anchor point in the bottom(y) middle (x) of myView
self.myView.setAnchorPoint(anchorPoint: CGPoint(x: 0.5, y: 1))

现在调用轮换

func Rotate(){

     let   rotation = UIViewPropertyAnimator(duration: 1, curve: .linear, animations: {

        self.myView.transform = self.myView.transform.rotated(by: CGFloat.pi/2)

        })
        rotation.startAnimation()

    }

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