ios - 如何使照片缩放，设置纵横比然后缩放在 Swift 中留下白色区域？

Question

[After scrolling : Problem White Screen] 1

After Zooming

[Before Zoom image setted aspect ratio]

我正在实现一个照片查看页面，其中只包含一张照片。功能:缩放。

由于图像的尺寸为 1024x510。我已经实现了纵横比并将 imageview 框架设置为屏幕尺寸。我已经使用 Scrollview 和 imageview 概念实现了。

问题是，当我缩放图像时，白屏也会被缩放。问题是缩放时 imageview 的空白区域。.代码

override func viewDidLoad() {
super.viewDidLoad()



print(imageIndex)
self.scrollV.maximumZoomScale = 5.0
self.scrollV.minimumZoomScale = 1.0
 self.scrollV.contentSize = self.view.bounds.size;
self.scrollV.delegate = self

let urlStr : NSString = vehicleImages[imageIndex].stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding)!




url=NSURL(string: urlStr as String)
imageView.kf_setImageWithURL(url,placeholderImage: UIImage(named: "placeholder.png"))

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

}

Answer 1

看看这些方法。可能会有帮助。我将 ScrollView 拉伸(stretch)到 Controller 的 View 大小。 customizeScrollView() 将计算最小和最大比例选项。 centerImageView() 会将 UIImageView 放在你的 UIScrollView 的中心

fileprivate func customizeScrollView() {
    guard let image = imageView?.image else { return }
    var minZoom = fmin(self.view.frame.width / image.size.width, self.view.frame.height / image.size.height)
    minZoom = fmin(1.0, minZoom)

    scrollView?.contentSize = image.size
    scrollView?.minimumZoomScale = minZoom
    scrollView?.addSubview(self.imageView!)
    scrollView?.setZoomScale(minZoom, animated: false)
    centerImageView()
}

fileprivate func centerImageView() {
    guard let imageView = imageView else { return }
    guard let scrollView = scrollView else { return }

    let boundsSize = scrollView.bounds.size
    var frameToCenter = imageView.frame

    // Center horizontally
    if frameToCenter.size.width < boundsSize.width {
        frameToCenter.origin.x = (boundsSize.width - frameToCenter.size.width) / 2
    } else {
        frameToCenter.origin.x = 0
    }

    // Center vertically
    if frameToCenter.size.height < boundsSize.height {
        frameToCenter.origin.y = (boundsSize.height - frameToCenter.size.height) / 2
    } else {
        frameToCenter.origin.y = 0
    }

    imageView.frame = frameToCenter
}

还有 UIScrollViewDelegate 方法:

/// `UIScrollViewDelegate` protocol implementation
extension ImagePreviewController: UIScrollViewDelegate {

    public func viewForZooming(in scrollView: UIScrollView) -> UIView? {
        return imageView
    }

    public func scrollViewDidZoom(_ scrollView: UIScrollView) {
        centerImageView()
    }
}