25

类似于 iOS 照片应用程序，用户通过捏合来放大和缩小图像：

UIView > UIScrollView > UIImageView > UIImage

最初，我遇到了缩放比例 1 以下的问题：图像偏离中心。我通过这样做修复了它：

func scrollViewDidZoom(scrollView: UIScrollView) {
        let offsetX = max((scrollView.bounds.width - scrollView.contentSize.width) * 0.5, 0)
        let offsetY = max((scrollView.bounds.height - scrollView.contentSize.height) * 0.5, 0)
        scrollView.contentInset = UIEdgeInsetsMake(offsetY, offsetX, 0, 0)
}

这在缩小时效果很好。

UIImage 内容模式为 aspectFit

问题

当我ZOOM IN时，当 zoomScale 大于 1 时，滚动视图插图需要拥抱滚动视图包含的 UIImage 的周围环境。这消除了 UIImage 周围的死区。IE，通过捏合或双击放大时的照片应用程序。

试过了

    func scrollViewDidZoom(scrollView: UIScrollView) {
    if scrollView.zoomScale > 1 {
        let imageScale = (self.imageView.bounds.width/self.imageView.image!.size.width)
        let imageWidth = self.imageView.image!.size.width * imageScale
        let imageHeight = self.imageView.image!.size.height * imageScale
        scrollView.contentInset = UIEdgeInsetsMake(((scrollView.frame.height - imageHeight) * 0.5), (scrollView.frame.width - imageWidth) * 0.5 , 0, 0)
        print (scrollView.contentInset.top)
    }
    else {

        let offsetX = max((scrollView.bounds.width - scrollView.contentSize.width) * 0.5, 0)
        let offsetY = max((scrollView.bounds.height - scrollView.contentSize.height) * 0.5, 0)
        scrollView.contentInset = UIEdgeInsetsMake(offsetY, offsetX, 0, 0)
    }
}

上面的添加似乎仍然改变了插图的数量。

更新（已添加图片）

第一张图片显示了默认布局。放大时的休息显示......

在此处输入图像描述

4

3 回答 3

42

你的方法看起来是正确的。您需要更新您的代码，如下所示。

    func scrollViewDidZoom(scrollView: UIScrollView) {
    
    if scrollView.zoomScale > 1 {
        
        if let image = imageView.image {
            
            let ratioW = imageView.frame.width / image.size.width
            let ratioH = imageView.frame.height / image.size.height
            
            let ratio = ratioW < ratioH ? ratioW:ratioH
            
            let newWidth = image.size.width*ratio
            let newHeight = image.size.height*ratio
            
            let left = 0.5 * (newWidth * scrollView.zoomScale > imageView.frame.width ? (newWidth - imageView.frame.width) : (scrollView.frame.width - scrollView.contentSize.width))
            let top = 0.5 * (newHeight * scrollView.zoomScale > imageView.frame.height ? (newHeight - imageView.frame.height) : (scrollView.frame.height - scrollView.contentSize.height))
            
            scrollView.contentInset = UIEdgeInsetsMake(top, left, top, left)
        }
    } else {
        scrollView.contentInset = UIEdgeInsetsZero
    }
}

斯威夫特 5

    func scrollViewDidZoom(scrollView: UIScrollView) {
    
    if scrollView.zoomScale > 1 {

        if let image = imageView.image {

            let ratioW = imageView.frame.width / image.size.width
            let ratioH = imageView.frame.height / image.size.height

            let ratio = ratioW < ratioH ? ratioW:ratioH

            let newWidth = image.size.width*ratio
            let newHeight = image.size.height*ratio

            let left = 0.5 * (newWidth * scrollView.zoomScale > imageView.frame.width ? (newWidth - imageView.frame.width) : (scrollView.frame.width - scrollView.contentSize.width))
            let top = 0.5 * (newHeight * scrollView.zoomScale > imageView.frame.height ? (newHeight - imageView.frame.height) : (scrollView.frame.height - scrollView.contentSize.height))

            scrollView.contentInset = UIEdgeInsets(top: top, left: left, bottom: top, right: left)
        }
    } else {
        scrollView.contentInset = .zero
    }
}
于 2016-11-08T06:47:55.357 回答
6

斯威夫特 5

func scrollViewDidZoom(_ scrollView: UIScrollView) {
    if scrollView.zoomScale > 1 {
        if let image = imageView.image {

            let ratioW = imageView.frame.width / image.size.width
            let ratioH = imageView.frame.height / image.size.height

            let ratio = ratioW < ratioH ? ratioW : ratioH

            let newWidth = image.size.width * ratio
            let newHeight = image.size.height * ratio

            let left = 0.5 * (newWidth * scrollView.zoomScale > imageView.frame.width ? (newWidth - imageView.frame.width) : (scrollView.frame.width - scrollView.contentSize.width))
            let top = 0.5 * (newHeight * scrollView.zoomScale > imageView.frame.height ? (newHeight - imageView.frame.height) : (scrollView.frame.height - scrollView.contentSize.height))

            scrollView.contentInset = UIEdgeInsets(top: top, left: left, bottom: top, right: left)
        }
    } else {
        scrollView.contentInset = UIEdgeInsets.zero
    }
}
于 2019-06-25T17:55:39.827 回答
1

快速 4

func scrollViewDidZoom(_ scrollView: UIScrollView) {

        if scrollView.zoomScale > 1 {

            if let image = self.imageViewZoom.image {

                let ratioW = self.imageViewZoom.frame.width / image.size.width
                let ratioH = self.imageViewZoom.frame.height / image.size.height

                let ratio = ratioW < ratioH ? ratioW:ratioH

                let newWidth = image.size.width*ratio
                let newHeight = image.size.height*ratio

                let left = 0.5 * (newWidth * scrollView.zoomScale > self.imageViewZoom.frame.width ? (newWidth - self.imageViewZoom.frame.width) : (scrollView.frame.width - scrollView.contentSize.width))
                let top = 0.5 * (newHeight * scrollView.zoomScale > self.imageViewZoom.frame.height ? (newHeight - self.imageViewZoom.frame.height) : (scrollView.frame.height - scrollView.contentSize.height))

                scrollView.contentInset = UIEdgeInsetsMake(top, left, top, left)
            }
        } else {
            scrollView.contentInset = UIEdgeInsets.zero
        }
    }
于 2018-05-31T09:17:06.557 回答