下面的 Swift 代码管理 UIScrollView
内的 UIImage
的放大和缩小。
双击时,图像会向中心放大并向中心缩小。
问题:
需要更改哪些代码才能将放大点设置为用户在屏幕上触摸的图像区域的中心?
(例如,如果用户双击图像的左上角,图像将相应地放大到图像的左上角。)
class ScrollViewController: UIViewController, UIScrollViewDelegate {
var scrollView: UIScrollView!
var imageView: UIImageView!
override func viewDidLoad() {
super.viewDidLoad()
imageView = UIImageView(image: UIImage(named: "image.png"))
scrollView = UIScrollView(frame: view.bounds)
scrollView.backgroundColor = UIColor.blackColor()
scrollView.contentSize = imageView.bounds.size
scrollView.autoresizingMask = [UIViewAutoresizing.FlexibleWidth, UIViewAutoresizing.FlexibleHeight]
scrollView.contentOffset = CGPoint(x: 1000, y: 450)
scrollView.addSubview(imageView)
view.addSubview(scrollView)
scrollView.delegate = self
setZoomScale()
setupGestureRecognizer()
}
func viewForZoomingInScrollView(scrollView: UIScrollView) -> UIView? {
return imageView
}
override func viewWillLayoutSubviews() {
setZoomScale()
}
func setZoomScale() {
let imageViewSize = imageView.bounds.size
let scrollViewSize = scrollView.bounds.size
let widthScale = scrollViewSize.width / imageViewSize.width
let heightScale = scrollViewSize.height / imageViewSize.height
scrollView.minimumZoomScale = min(widthScale, heightScale)
scrollView.zoomScale = 1.0
}
func scrollViewDidZoom(scrollView: UIScrollView) {
let imageViewSize = imageView.frame.size
let scrollViewSize = scrollView.bounds.size
let verticalPadding = imageViewSize.height < scrollViewSize.height ? (scrollViewSize.height - imageViewSize.height) / 2 : 0
let horizontalPadding = imageViewSize.width < scrollViewSize.width ? (scrollViewSize.width - imageViewSize.width) / 2 : 0
scrollView.contentInset = UIEdgeInsets(top: verticalPadding, left: horizontalPadding, bottom: verticalPadding, right: horizontalPadding)
}
func setupGestureRecognizer() {
let doubleTap = UITapGestureRecognizer(target: self, action: "handleDoubleTap:")
doubleTap.numberOfTapsRequired = 2
scrollView.addGestureRecognizer(doubleTap)
}
func handleDoubleTap(recognizer: UITapGestureRecognizer) {
if (scrollView.zoomScale > scrollView.minimumZoomScale) {
scrollView.setZoomScale(scrollView.minimumZoomScale, animated: true)
} else {
scrollView.setZoomScale(scrollView.maximumZoomScale, animated: true)
}
}
}
最佳答案
根据 this post .对我来说效果很好。
func handleDoubleTap(recognizer: UITapGestureRecognizer) {
if (scrollView.zoomScale > scrollView.minimumZoomScale) {
scrollView.setZoomScale(scrollView.minimumZoomScale, animated: true)
} else {
let touchPoint = recognizer.locationInView(view)
let scrollViewSize = scrollView.bounds.size
let width = scrollViewSize.width / scrollView.maximumZoomScale
let height = scrollViewSize.height / scrollView.maximumZoomScale
let x = touchPoint.x - (width/2.0)
let y = touchPoint.y - (height/2.0)
let rect = CGRectMake(x, y, width, height)
scrollView.zoomToRect(rect, animated: true)
}
}
关于ios - 使用 Swift 中的 UIScrollView 从用户的触摸点放大图像,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/38855581/