在 UIImageView 中应用了适合图像的方面后，如何知道图像的大小

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最佳答案

请看@Paul-de-Lange 的回答，而不是这个

我找不到任何易于访问的变量，有这样的，所以这里是蛮力的方式:

- (CGSize) aspectScaledImageSizeForImageView:(UIImageView *)iv image:(UIImage *)im {


float x,y;
float a,b;
x = iv.frame.size.width;
y = iv.frame.size.height;
a = im.size.width;
b = im.size.height;


if ( x == a && y == b ) {           // image fits exactly, no scaling required
// return iv.frame.size;
}
else if ( x > a && y > b ) {         // image fits completely within the imageview frame
if ( x-a > y-b ) {              // image height is limiting factor, scale by height
a = y/b * a;
b = y;
} else {
b = x/a * b;                // image width is limiting factor, scale by width
a = x;
}
}
else if ( x < a && y < b ) {        // image is wider and taller than image view
if ( a - x > b - y ) {          // height is limiting factor, scale by height
a = y/b * a;
b = y;
} else {                        // width is limiting factor, scale by width
b = x/a * b;
a = x;
}
}
else if ( x < a && y > b ) {        // image is wider than view, scale by width
b = x/a * b;
a = x;
}
else if ( x > a && y < b ) {        // image is taller than view, scale by height
a = y/b * a;
b = y;
}
else if ( x == a ) {
a = y/b * a;
b = y;
} else if ( y == b ) {
b = x/a * b;
a = x;
}
return CGSizeMake(a,b);


}

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+(UIImage *)CreateAResizeImage:(UIImage *)Img ThumbSize:(CGSize)ThumbSize
{
float actualHeight = Img.size.height;
float actualWidth = Img.size.width;


if(actualWidth==actualHeight)
{
actualWidth = ThumbSize.width;
actualHeight = ThumbSize.height;
}


float imgRatio = actualWidth/actualHeight;
float maxRatio = ThumbSize.width/ThumbSize.height; //320.0/480.0;




if(imgRatio!=maxRatio)
{
if(imgRatio < maxRatio)
{
imgRatio = ThumbSize.height / actualHeight; //480.0 / actualHeight;
actualWidth = imgRatio * actualWidth;
actualHeight = ThumbSize.height; //480.0;
}
else
{
imgRatio = ThumbSize.width / actualWidth; //320.0 / actualWidth;
actualHeight = imgRatio * actualHeight;
actualWidth = ThumbSize.width; //320.0;
}
}
else
{
actualWidth = ThumbSize.width;
actualHeight = ThumbSize.height;
}




CGRect rect = CGRectMake(0, 0, (int)actualWidth, (int)actualHeight);
UIGraphicsBeginImageContext(rect.size);
[Img drawInRect:rect];
UIImage *NewImg = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();


return NewImg;
}

小开

为什么不使用操作系统函数使用 AspectRatioInsideRect？

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这个简单的函数将计算图像的大小后，方面适合:

Swift 5.1

extension UIImageView {


var imageSizeAfterAspectFit: CGSize {
var newWidth: CGFloat
var newHeight: CGFloat


guard let image = image else { return frame.size }


if image.size.height >= image.size.width {
newHeight = frame.size.height
newWidth = ((image.size.width / (image.size.height)) * newHeight)


if CGFloat(newWidth) > (frame.size.width) {
let diff = (frame.size.width) - newWidth
newHeight = newHeight + CGFloat(diff) / newHeight * newHeight
newWidth = frame.size.width
}
} else {
newWidth = frame.size.width
newHeight = (image.size.height / image.size.width) * newWidth


if newHeight > frame.size.height {
let diff = Float((frame.size.height) - newHeight)
newWidth = newWidth + CGFloat(diff) / newWidth * newWidth
newHeight = frame.size.height
}
}
return .init(width: newWidth, height: newHeight)
}
}

目标丙:

 -(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);


}

小开

也许不适合你的情况，但这个简单的方法在类似的情况下解决了我的问题:

    UIImageView *imageView = [[UIImageView alloc] initWithImage:bigSizeImage];
[imageView sizeToFit];

在图像视图执行 sizeToFit 之后，如果您查询 ImageView.frame.size，您将获得适合新图像大小的新图像视图大小。

小开

我想用 AVMakeRectWithAspectRatioInsideRect() 不包括 AVFoundation 框架。

因此，我实现了以下两个实用函数:

CGSize CGSizeAspectFit(CGSize aspectRatio, CGSize boundingSize)
{
float mW = boundingSize.width / aspectRatio.width;
float mH = boundingSize.height / aspectRatio.height;
if( mH < mW )
boundingSize.width = boundingSize.height / aspectRatio.height * aspectRatio.width;
else if( mW < mH )
boundingSize.height = boundingSize.width / aspectRatio.width * aspectRatio.height;
return boundingSize;
}


CGSize CGSizeAspectFill(CGSize aspectRatio, CGSize minimumSize)
{
float mW = minimumSize.width / aspectRatio.width;
float mH = minimumSize.height / aspectRatio.height;
if( mH > mW )
minimumSize.width = minimumSize.height / aspectRatio.height * aspectRatio.width;
else if( mW > mH )
minimumSize.height = minimumSize.width / aspectRatio.width * aspectRatio.height;
return minimumSize;
}

编辑: 通过删除重复的部分优化以下。

CGSize CGSizeAspectFit(const CGSize aspectRatio, const CGSize boundingSize)
{
CGSize aspectFitSize = CGSizeMake(boundingSize.width, boundingSize.height);
float mW = boundingSize.width / aspectRatio.width;
float mH = boundingSize.height / aspectRatio.height;
if( mH < mW )
aspectFitSize.width = mH * aspectRatio.width;
else if( mW < mH )
aspectFitSize.height = mW * aspectRatio.height;
return aspectFitSize;
}


CGSize CGSizeAspectFill(const CGSize aspectRatio, const CGSize minimumSize)
{
CGSize aspectFillSize = CGSizeMake(minimumSize.width, minimumSize.height);
float mW = minimumSize.width / aspectRatio.width;
float mH = minimumSize.height / aspectRatio.height;
if( mH > mW )
aspectFillSize.width = mH * aspectRatio.width;
else if( mW > mH )
aspectFillSize.height = mW * aspectRatio.height;
return aspectFillSize;
}

编辑完毕

它接受给定的大小(第一个参数)并维护其长宽比。然后它尽可能地填充给定的边界(第二个参数) ，而不违反高宽比。

用这个来回答最初的问题:

// Using aspect fit, scale the image (size) to the image view's size.
CGSize sizeBeingScaledTo = CGSizeAspectFit(theImage.size, theImageView.frame.size);

请注意图像如何确定长宽比，而图像视图确定要填充的大小。

非常欢迎反馈。

小开

公认的答案是难以置信的复杂，并且在某些边缘情况下是失败的。我认为这个解决方案要优雅得多:

- (CGSize) sizeOfImage:(UIImage*)image inAspectFitImageView:(UIImageView*)imageView
{
UKAssert(imageView.contentMode == UIViewContentModeScaleAspectFit, @"Image View must use contentMode = UIViewContentModeScaleAspectFit");


CGFloat imageViewWidth = imageView.bounds.size.width;
CGFloat imageViewHeight = imageView.bounds.size.height;


CGFloat imageWidth = image.size.width;
CGFloat imageHeight = image.size.height;


CGFloat scaleFactor = MIN(imageViewWidth / imageWidth, imageViewHeight / imageHeight);


return CGSizeMake(image.size.width*scaleFactor, image.size.height*scaleFactor);
}

小开

下面是我对同样问题的解决方案: Https://github.com/alexgarbarev/uiimageview-imageframe

优点:

支持 UIViewContentMode 模式
可以分别查询天平和正交
可以从 UIImageView 查询图像帧

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我还想计算高度后的高宽比应用，以便能够计算表格视图的单元格的高度。所以，我通过一点点数学就做到了

ratio = width / height

身高就会变成

height = width / ratio

所以代码片段应该是

UIImage *img = [UIImage imageNamed:@"anImage"];
float aspectRatio = img.size.width/img.size.height;
float requiredHeight = self.view.bounds.size.width / aspectRatio;

小开

我在 Swift 中使用了以下内容:

private func CGSizeAspectFit(aspectRatio:CGSize,boundingSize:CGSize) -> CGSize
{
var aspectFitSize = boundingSize
let mW = boundingSize.width / aspectRatio.width
let mH = boundingSize.height / aspectRatio.height
if( mH < mW )
{
aspectFitSize.width = mH * aspectRatio.width
}
else if( mW < mH )
{
aspectFitSize.height = mW * aspectRatio.height
}
return aspectFitSize
}


private func CGSizeAspectFill(aspectRatio:CGSize,minimumSize:CGSize) -> CGSize
{
var aspectFillSize = minimumSize
let mW = minimumSize.width / aspectRatio.width
let mH = minimumSize.height / aspectRatio.height
if( mH > mW )
{
aspectFillSize.width = mH * aspectRatio.width
}
else if( mW > mH )
{
aspectFillSize.height = mW * aspectRatio.height
}
return aspectFillSize
}

我是这样使用它的:

let aspectSize  = contentMode == .ScaleAspectFill ? CGSizeAspectFill(oldSize,minimumSize: newSize) : CGSizeAspectFit(oldSize, boundingSize: newSize)


let newRect = CGRect( x: (newSize.width - aspectSize.width)/2, y: (newSize.height - aspectSize.height)/2, width: aspectSize.width, height: aspectSize.height)


CGContextSetFillColorWithColor(context,IOSXColor.whiteColor().CGColor)
CGContextFillRect(context, CGRect(origin: CGPointZero,size: newSize))
CGContextDrawImage(context, newRect, cgImage)

小开

上面提到的方法从来没有给出所需的值。由于长宽匹配保持相同的长宽比，我们只需要简单的数学计算值

检测长宽比

CGFloat imageViewAspectRatio = backgroundImageView.bounds.size.width / backgroundImageView.bounds.size.height;
CGFloat imageAspectRatio =  backgroundImageView.image.size.width / backgroundImageView.image.size.height;
CGFloat mulFactor = imageViewAspectRatio/imageAspectRatio;

获取新的值

CGFloat newImageWidth = mulFactor * backgroundImageView.bounds.size.width;
CGFloat newImageHeight = mulFactor * backgroundImageView.bounds.size.height;

小开

对于 Swift 使用以下代码

func imageSizeAspectFit(imgview: UIImageView) -> CGSize {
var newwidth: CGFloat
var newheight: CGFloat
let image: UIImage = imgFeed.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 {
let diff: CGFloat = 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 {
let diff: CGFloat = imgview.frame.size.height - newheight
newwidth = newwidth + diff / newwidth * newwidth
newheight = imgview.frame.size.height
}
}


print(newwidth, newheight)
//adapt UIImageView size to image size
return CGSizeMake(newwidth, newheight)
}

调用函数

imgFeed.sd_setImageWithURL(NSURL(string:"Your image URL")))
self.imageSizeAfterAspectFit(imgFeed)

小开

这一行就可以完成这项工作

CGSize sizeInView = AVMakeRectWithAspectRatioInsideRect(imgViewFake.image.size, imgViewFake.bounds).size;

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迅捷3 人类可读版本

extension UIImageView {


/// Find the size of the image, once the parent imageView has been given a contentMode of .scaleAspectFit
/// Querying the image.size returns the non-scaled size. This helper property is needed for accurate results.
var aspectFitSize: CGSize {
guard let image = image else { return CGSize.zero }


var aspectFitSize = CGSize(width: frame.size.width, height: frame.size.height)
let newWidth: CGFloat = frame.size.width / image.size.width
let newHeight: CGFloat = frame.size.height / image.size.height


if newHeight < newWidth {
aspectFitSize.width = newHeight * image.size.width
} else if newWidth < newHeight {
aspectFitSize.height = newWidth * image.size.height
}


return aspectFitSize
}


/// Find the size of the image, once the parent imageView has been given a contentMode of .scaleAspectFill
/// Querying the image.size returns the non-scaled, vastly too large size. This helper property is needed for accurate results.
var aspectFillSize: CGSize {
guard let image = image else { return CGSize.zero }


var aspectFillSize = CGSize(width: frame.size.width, height: frame.size.height)
let newWidth: CGFloat = frame.size.width / image.size.width
let newHeight: CGFloat = frame.size.height / image.size.height


if newHeight > newWidth {
aspectFillSize.width = newHeight * image.size.width
} else if newWidth > newHeight {
aspectFillSize.height = newWidth * image.size.height
}


return aspectFillSize
}


}

小开

Swift 3 UIImageView 扩展:

import AVFoundation


extension UIImageView {
var imageSize: CGSize {
if let image = image {
return AVMakeRect(aspectRatio: image.size, insideRect: bounds).size
}
return CGSize.zero
}
}

小开

如果你只知道图像视图的宽度，并且图像的高度是动态的，那么你需要根据给定的宽度缩放图像的高度，以去除图像上下的空白。使用以下给你方法根据屏幕的标准宽度缩放图像的高度。

-(UIImage*)imageWithImage: (UIImage*) sourceImage scaledToWidth: (float) i_width
{
float oldWidth = sourceImage.size.width;
float scaleFactor = i_width / oldWidth;


float newHeight = sourceImage.size.height * scaleFactor;
float newWidth = oldWidth * scaleFactor;


UIGraphicsBeginImageContext(CGSizeMake(newWidth, newHeight));
[sourceImage drawInRect:CGRectMake(0, 0, newWidth, newHeight)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}

然后从 cellForRowAtIndexPath: 方法调用它，如下所示:

UIImage *img = [dictImages objectForKey:yourImageKey]; // loaded the image
cell.imgView.image = [self imageWithImage:img scaledToWidth:self.view.frame.size.width];

小开

这是我的没有 AVFoundation 的解决方案。

首先，这里有一个 CGSize 扩展，用于计算适合另一种尺寸的尺寸:

extension CGSize
{
func sizeThatFitsSize(_ aSize: CGSize) -> CGSize
{
let width = min(self.width * aSize.height / self.height, aSize.width)
return CGSize(width: width, height: self.height * width / self.width)
}
}

因此 OP 问题的解决方案归结为:

let resultSize = image.size.sizeThatFitsSize(imageView.bounds.size)

这里还有一个扩展，用于在另一个 rect 中安装 rect (它利用了上面的 CGSize 扩展) :

extension CGRect
{
func rectThatFitsRect(_ aRect:CGRect) -> CGRect
{
let sizeThatFits = self.size.sizeThatFitsSize(aRect.size)


let xPos = (aRect.size.width - sizeThatFits.width) / 2
let yPos = (aRect.size.height - sizeThatFits.height) / 2


let ret = CGRect(x: xPos, y: yPos, width: sizeThatFits.width, height: sizeThatFits.height)
return ret
}
}

小开

.aspectFit图像的帧是-

import AVFoundation

let x: CGRect = AVMakeRect(aspectRatio: myImage.size, insideRect: sampleImageView.frame)

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Swift 4版本

extension CGSize { enum AspectMode { case fit case fill } enum Orientation { case portrait case landscape } func aspectCorrectSizeToFit(targetSize: CGSize, aspectMode: AspectMode = .fill) -> CGSize { switch aspectMode { case .fill: return aspectFill(targetSize: targetSize) case .fit: return aspectFit(targetSize: targetSize) } } var orientation: Orientation { if height >= width { return .portrait } else { return .landscape } } func aspectFit(targetSize: CGSize) -> CGSize { let wRatio = targetSize.width / width let hRatio = targetSize.height / height let scale = min(wRatio, hRatio) return applying(CGAffineTransform(scaleX: scale, y: scale)) } func aspectFill(targetSize: CGSize) -> CGSize { let wRatio = targetSize.width / width let hRatio = targetSize.height / height let scale = max(wRatio, hRatio) return applying(CGAffineTransform(scaleX: scale, y: scale)) } }

小开

迅捷5 延伸

extension CGSize { func aspectFit(to size: CGSize) -> CGSize { let mW = size.width / self.width; let mH = size.height / self.height; var result = size if( mH < mW ) { result.width = size.height / self.height * self.width; } else if( mW < mH ) { result.height = size.width / self.width * self.height; } return result; } func aspectFill(to size: CGSize) -> CGSize { let mW = size.width / self.width; let mH = size.height / self.height; var result = size if( mH > mW ) { result.width = size.height / self.height * self.width; } else if( mW > mH ) { result.height = size.width / self.width * self.height; } return result; } }