ios - iOS Swift：在不调整大小的情况下旋转和缩放 UIView

Question

我有一个 UIView，我想通过平移和捏合手势进行缩放和旋转。但问题是当我缩放视图时，然后当我旋转它时，它会在缩放之前调整回初始值。

extension UIView {

    func addPinchGesture() {
        var pinchGesture = UIPinchGestureRecognizer()
        pinchGesture = UIPinchGestureRecognizer(target: self,
                                                action: #selector(handlePinchGesture(_:)))
        self.addGestureRecognizer(pinchGesture)
    }

    @objc func handlePinchGesture(_ sender: UIPinchGestureRecognizer) {
        self.transform = self.transform.scaledBy(x: sender.scale, y: sender.scale)
        sender.scale = 1
    }

}

// ROTATION
extension UIView {

    func addRotationGesture() {
        var rotationGesture = RotationGestureRecognizer()
        rotationGesture = RotationGestureRecognizer(target: self,
                                                    action: #selector(handleRotationGesture(_:)))
        self.addGestureRecognizer(rotationGesture)
    }

    @objc func handleRotationGesture(_ sender: RotationGestureRecognizer) {
        var originalRotation = CGFloat()
        switch sender.state {
        case .began:
            sender.rotation = sender.lastRotation
            originalRotation = sender.rotation
        case .changed:
            let newRotation = sender.rotation + originalRotation
            self.transform = CGAffineTransform(rotationAngle: newRotation) // Rotation is fine but it is resizing view
//            self.transform = self.transform.rotated(by: newRotation / CGFloat(180 * Double.pi)) // NOT WORKING i.e. irregular rotation
        case .ended:
            sender.lastRotation = sender.rotation
        default:
            break
        }
    }

}

缩放前

缩放后

旋转后

我希望它在不影响视图大小的情况下旋转。我怎样才能做到这一点？

标签： iosswiftuiviewcgaffinetransform

Answer 1

应用旋转变换时，您正在重置视图的比例变换。创建一个属性以保持视图的原始比例。

var currentScale: CGFloat = 0

捏合完成后，将 currentScale 值存储到当前比例。然后在旋转时也使用这个比例，然后再应用旋转。

let scaleTransform = CGAffineTransform(scaleX: currentScale, y: currentScale)

let concatenatedTransform = scaleTransform.rotated(by: newRotation)
self.transform = concatenatedTransform

您正在使用扩展来添加手势识别器，因此您无法存储 currentScale。您还可以从当前变换值中获取视图的比例值。这是您的代码的样子，

extension UIView {

    var currentScale: CGPoint {
        let a = transform.a
        let b = transform.b
        let c = transform.c
        let d = transform.d

        let sx = sqrt(a * a + b * b)
        let sy = sqrt(c * c + d * d)

        return CGPoint(x: sx, y: sy)
    }


    func addPinchGesture() {
        var pinchGesture = UIPinchGestureRecognizer()
        pinchGesture = UIPinchGestureRecognizer(target: self,
                                                action: #selector(handlePinchGesture(_:)))
        self.addGestureRecognizer(pinchGesture)
    }

    @objc func handlePinchGesture(_ sender: UIPinchGestureRecognizer) {
        self.transform = self.transform.scaledBy(x: sender.scale, y: sender.scale)
        sender.scale = 1
    }

}

// ROTATION
extension UIView {

    func addRotationGesture() {
        var rotationGesture = RotationGestureRecognizer()
        rotationGesture = RotationGestureRecognizer(target: self,
                                                    action: #selector(handleRotationGesture(_:)))
        self.addGestureRecognizer(rotationGesture)
    }

    @objc func handleRotationGesture(_ sender: RotationGestureRecognizer) {
        var originalRotation = CGFloat()
        switch sender.state {
        case .began:
            sender.rotation = sender.lastRotation
            originalRotation = sender.rotation
        case .changed:
            let scale = CGAffineTransform(scaleX: currentScale.x, y: currentScale.y)
            let newRotation = sender.rotation + originalRotation

            self.transform = scale.rotated(by: newRotation)
        case .ended:
            sender.lastRotation = sender.rotation
        default:
            break
        }
    }
}

我将此答案用作提取比例值的参考。