Question

image.size的{{1}}属性给出了原始UIImageView的大小。我想知道自动缩放图像放入UIImage时的大小（通常小于原始图像）。

例如，我将图像设置为UIImageView。现在我想知道它在屏幕上的新高度和宽度，以便我可以准确地绘制新的缩放图像。

有没有办法做到这一点，而不是基于UIImageView尺寸和＆amp; UIImage原始大小（基本上是逆向工程缩放）？

Answer 1

<强>目标-C：

-(CGRect)frameForImage:(UIImage*)image inImageViewAspectFit:(UIImageView*)imageView
{
    float imageRatio = image.size.width / image.size.height;
    float viewRatio = imageView.frame.size.width / imageView.frame.size.height;
    if(imageRatio < viewRatio)
    {
        float scale = imageView.frame.size.height / image.size.height;
        float width = scale * image.size.width;
        float topLeftX = (imageView.frame.size.width - width) * 0.5;
        return CGRectMake(topLeftX, 0, width, imageView.frame.size.height);
    }
    else
    {
        float scale = imageView.frame.size.width / image.size.width;
        float height = scale * image.size.height;
        float topLeftY = (imageView.frame.size.height - height) * 0.5;

        return CGRectMake(0, topLeftY, imageView.frame.size.width, height);
    }
}

Swift 4：

func frame(for image: UIImage, inImageViewAspectFit imageView: UIImageView) -> CGRect {
  let imageRatio = (image.size.width / image.size.height)
  let viewRatio = imageView.frame.size.width / imageView.frame.size.height
  if imageRatio < viewRatio {
    let scale = imageView.frame.size.height / image.size.height
    let width = scale * image.size.width
    let topLeftX = (imageView.frame.size.width - width) * 0.5
    return CGRect(x: topLeftX, y: 0, width: width, height: imageView.frame.size.height)
  } else {
    let scale = imageView.frame.size.width / image.size.width
    let height = scale * image.size.height
    let topLeftY = (imageView.frame.size.height - height) * 0.5
    return CGRect(x: 0.0, y: topLeftY, width: imageView.frame.size.width, height: height)
  }
}

Answer 2

这个简单的函数将计算图像的大小： -

[imageView setFrame:AVMakeRectWithAspectRatioInsideRect(image.size, imageView.frame)];

有关详细信息，请参阅AVMakeRectWithAspectRatioInsideRect - AVFoundation。

Answer 3

这个简单的函数将在宽高比拟合后计算图像的大小：

-(CGSize)imageSizeAfterAspectFit:(UIImageView*)imgview{


    float newwidth;
    float newheight;

    UIImage *image=imgview.image;

    if (image.size.height>=image.size.width){
        newheight=imgview.frame.size.height;
        newwidth=(image.size.width/image.size.height)*newheight;

        if(newwidth>imgview.frame.size.width){
            float diff=imgview.frame.size.width-newwidth;
            newheight=newheight+diff/newheight*newheight;
            newwidth=imgview.frame.size.width;
        }

    }
    else{
        newwidth=imgview.frame.size.width;
        newheight=(image.size.height/image.size.width)*newwidth;

        if(newheight>imgview.frame.size.height){
            float diff=imgview.frame.size.height-newheight;
            newwidth=newwidth+diff/newwidth*newwidth;
            newheight=imgview.frame.size.height;
        }
    }

    NSLog(@"image after aspect fit: width=%f height=%f",newwidth,newheight);


    //adapt UIImageView size to image size
    //imgview.frame=CGRectMake(imgview.frame.origin.x+(imgview.frame.size.width-newwidth)/2,imgview.frame.origin.y+(imgview.frame.size.height-newheight)/2,newwidth,newheight);

    return CGSizeMake(newwidth, newheight);

}

Answer 4

cncool answer的改编，在swift中作为UIImageView扩展，也许它可能对某人有用：

extension UIImageView{
    func frameForImageInImageViewAspectFit() -> CGRect
    {
        if  let img = self.image {
            let imageRatio = img.size.width / img.size.height;

            let viewRatio = self.frame.size.width / self.frame.size.height;

            if(imageRatio < viewRatio)
            {
                let scale = self.frame.size.height / img.size.height;

                let width = scale * img.size.width;

                let topLeftX = (self.frame.size.width - width) * 0.5;

                return CGRectMake(topLeftX, 0, width, self.frame.size.height);
            }
            else
            {
                let scale = self.frame.size.width / img.size.width;

                let height = scale * img.size.height;

                let topLeftY = (self.frame.size.height - height) * 0.5;

                return CGRectMake(0, topLeftY, self.frame.size.width, height);
            }
        }

        return CGRectMake(0, 0, 0, 0)
    }
}

Answer 5

由于您已将图像视图设置为Aspect Fit，因此您可以简单地获取图像视图的高度和宽度以及原始图像的高度和宽度，并计算缩放图像的高度和宽度。 / p>

也就是说，更好这样做的方法是使用自定义视图而不是UIImageView。然后，在自定义视图中自己绘制图像。这样你就可以控制它的每个方面。

Answer 6

在@MeetDoshi之后，这是应该容纳该扩展名的扩展名。

extension UIImageView {
    /// Retrieve the scaled size of the image within this ImageView.
    /// - Returns: A CGRect representing the size of the image after scaling or nil if no image is set.
    func getScaledImageSize() -> CGRect? {
        if let image = self.image {
            return AVMakeRect(aspectRatio: image.size, insideRect: self.frame);
        }

        return nil;
    }
}

Answer 7

我写了一个有用的扩展，其中包括一些附加功能，可能值得一试。

包含的功能

func getScaledImageSize() -> CGRect?
func getScaledImageSizeWithPadding() -> CGRect?
func getPaddingTop() -> CGFloat? {
func getPaddingBottom() -> CGFloat? {
func getPaddingLeft() -> CGFloat? {
func getPaddingRight() -> CGFloat?
func getScaledCoordinate(forX x: CGFloat, andY y: CGFloat, multiplier:CGFloat = 100.0) -> CGPoint?
func getScaledCoordinateWithPadding(forX x: CGFloat, andY y: CGFloat, multiplier:CGFloat = 100.0) -> CGPoint?

https://gist.github.com/nathan-fiscaletti/e1b85f68559f305db7342bfff9574563

Answer 8

如果帧保持图像宽高比，则图像视图帧将与图像大小不同。

Answer 9

如何从框架中获取UIImageView大小？即imageView.frame？

如何在UIImageView中获得缩放的UIImage的大小？

9 个答案: