在UIScrollView中旋转UIImageView

Question

我在UIScrollView中放置了一个UIImageView。最终目标是在UIScrollView的范围内旋转、平移和缩放图片。平移和缩放效果很好。旋转最初也能成功，但当完成一次旋转后紧接着进行一次捏合缩放时，图像旋转会重置为0，而图像则被移出了UIScrollView。

请问有什么建议吗？

@IBOutlet weak var innerScrollView: UIScrollView!
        private weak var innerImageView: UIImageView?
        var beforeImage: UIImage?


        // MARK: -
        // MARK: UIViewController       

        override func viewDidLoad() {
            super.viewDidLoad()

            innerScrollView.delegate = self
            configureScrollView(innerScrollView, image: beforeImage)

            let recognizer = UIRotationGestureRecognizer(target: self, action: "rotateRecognizer:")
            if let imageView = innerImageView {
                imageView.addGestureRecognizer(recognizer)
            }
        }

        override func viewWillAppear(animated: Bool) {
            super.viewWillAppear(animated)

            resetScrollView(innerScrollView)
        }



        // MARK: -
        // MARK: Private Helpers

        private func resetScrollView(scrollView: UIScrollView) {

            let scaleWidth = scrollView.frame.size.width / scrollView.contentSize.width
            let scaleHeight = scrollView.frame.size.height / scrollView.contentSize.height

            let minScale = min(scaleHeight, scaleWidth)

            scrollView.minimumZoomScale = minScale
            scrollView.maximumZoomScale = 1.0
            scrollView.zoomScale = minScale
            centerScrollViewContents()

        }

        private func configureScrollView(scrollView: UIScrollView, image: UIImage?) {

            guard let img = image else {
                return
            }
            let imageView = UIImageView(image: image)
            imageView.userInteractionEnabled = true
            imageView.frame = CGRect(origin: CGPoint(x: 0, y: 0), size: img.size)
            scrollView.addSubview(imageView)
            scrollView.contentSize = img.size

            innerImageView = imageView
        }

        private func centerScrollViewContents() {
            let boundsSize = innerScrollView.bounds.size
            var contentsFrame = innerImageView!.frame

            if contentsFrame.size.width < boundsSize.width {
                contentsFrame.origin.x = (boundsSize.width - contentsFrame.size.width) / 2.0
            } else {
                contentsFrame.origin.x = 0.0
            }

            if contentsFrame.size.height < boundsSize.height {
                contentsFrame.origin.y = (boundsSize.height - contentsFrame.size.height) / 2.0
            } else {
                contentsFrame.origin.y = 0.0
            }

            innerImageView!.frame = contentsFrame
        }

        func rotateRecognizer(recognizer: UIRotationGestureRecognizer) {

            print("The content Offset is \(innerScrollView.contentOffset)")
            guard let recView = recognizer.view else {
                return
            }

            recView.transform = CGAffineTransformRotate(recView.transform, recognizer.rotation);
            recognizer.rotation = 0;
        }



        // MARK: -
        // MARK: UIGestureRecognizer Delegate Protocol

        func viewForZoomingInScrollView(scrollView: UIScrollView) -> UIView? {

            if let imageView = scrollView.subviews.first as? UIImageView {
                return imageView
            }
            return nil
        }

- Cory

---

请发布您的平移手势识别器代码。问题很可能就在那里。我敢打赌，您是从标识变换开始而不是从图像视图的当前变换开始的。（您的旋转方法正在执行正确的操作，并从当前变换开始。） - Duncan C

@DuncanC 嗯，我没有平移或捏合手势识别器。我正在使用UIScrollView。你认为这是问题吗？ - Cory

你应该旋转innerImageView，而不是“recView”吧？ - Duncan C

如果您正在操作滚动视图的变换，那么这可能就是问题所在。您应该将旋转应用于图像视图，而不是滚动视图。（虽然使旋转的中心点正确工作可能是一个挑战。） - Duncan C

Answer 1

我让它工作了。这里还有另一个提议的解决方案here，但我的不同。

使用scrollview很容易进行缩放和平移，但是当添加旋转时，它会立即重置，就像你说的那样（对我也发生过）。我所做的是完全放弃scrollView的手势，不依赖于其代理。我为平移、缩放和旋转添加了自己的手势识别器。然后，您可以根据需要组合它们：允许其中两个同时感知变化，甚至是所有三个。在我的解决方案中，我希望单独感知平移，而将缩放和旋转感知在一起。您可以在以下方法中实现：

func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool 

请看下面我的其余代码。 当然，在我的示例中，我有一个UIView，而不是ImageView，但从变换的角度来看，这并不重要。

private struct Constants {
    private init() {}

    static let minZoom = CGFloat(0.3)
    static let maxZoom = CGFloat(6)
}

private var activeView: UIView
private var savedTransform: CGAffineTransform

// Represents rotation performed since the last transform save
private var editedRotation = TransformConstants.defaultRotation
// Represents scaling performed since the last transform save
private var editedScale = TransformConstants.defaultScale

override func didPan(recognizer: UIPanGestureRecognizer) {
    let translation = recognizer.translation(in: activeView)
    activeView.transform = savedTransform.translatedBy(x: translation.x, y: translation.y)

    if shouldSaveGestures(recognizer: recognizer) {
      saveChanges(operation: .pan)
      return
    }
}

override func didPinch(recognizer: UIPinchGestureRecognizer) {
    if shouldSaveGestures(recognizer: recognizer) {
      saveChanges(operation: .zoom)
      return
    }

    var scale = recognizer.scale

    if Constants.minZoom > scale * savedTransform.getScale().x {
      scale = Constants.minZoom / savedTransform.getScale().x
    } else if scale * savedTransform.getScale().x > Constants.maxZoom {
      scale = Constants.maxZoom / savedTransform.getScale().x
    }

    activeView.transform = savedTransform.scaledBy(x: scale, y: scale).rotated(by: editedRotation)
    editedScale = CGPoint(x: scale, y: scale)
}

override func didRotate(recognizer: UIRotationGestureRecognizer) {
    if shouldSaveGestures(recognizer: recognizer) {
      saveChanges(operation: .rotate)
      return
    }

    activeView.transform = savedTransform.scaledBy(x: editedScale.x, y: editedScale.y).rotated(by: recognizer.rotation)
    editedRotation = recognizer.rotation
}

private func shouldSaveGestures(recognizer: UIGestureRecognizer) -> Bool {
    return recognizer.state == .ended || recognizer.state == .failed
}

private func saveChanges(operation: OperationType) {
    savedTransform = activeView.transform
    editedScale = TransformConstants.defaultScale
    editedRotation = TransformConstants.defaultRotation
}

- Calin Drule