【发布时间】：2011-09-10 20:31:15
【问题描述】：
我正在将图像加载到模式为“Aspect Fit”的图像视图中。我需要知道我的图像被缩放到的大小。请帮忙。
【问题讨论】：
标签： iphone ipad uiimageview uiimage aspect-ratio
【发布时间】：2011-09-10 20:31:15
【问题描述】：
Swift 5 扩展
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;
}
}
【讨论】：
这个简单的函数将计算宽高比拟合后的图像大小：
斯威夫特 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 C：
-(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);
}
【讨论】：
-
接受的答案对我不起作用。但是这个答案做到了。而这个答案的真正美妙之处在于它不需要传递 UIImage 的任何显式引用，而是从 UIImageView 的图像内容中获取它。它也适用于方向变化。谢谢。
-
由于这总是在 UIImageView 上完成，因此可能值得将其塑造成一个类别方法 UIImageView。
-
它没有返回精确的帧
这一行就可以完成这项工作
CGSize sizeInView = AVMakeRectWithAspectRatioInsideRect(imgViewFake.image.size, imgViewFake.bounds).size;
【讨论】：
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))
}
}
【讨论】：
为什么不使用操作系统功能AVMakeRectWithAspectRatioInsideRect？
【讨论】：
-
这正是我们所需要的——
[imageView setFrame:AVMakeRectWithAspectRatioInsideRect(image.size, imageView.frame)]) -
不想包含 AVFoundation 框架？我在单独的答案中向
AVMakeRectWithAspectRatioInsideRect()发布了两个替代实用程序函数。 -
这应该是公认的答案。上面接受的答案不正确，在不同情况下都不起作用。
-
对于 swifters：import AVFoundation let height = AVMakeRectWithAspectRatioInsideRect((image?.size)!, imageView.frame).height
斯威夫特 4：
.aspectFit 图像的框架是 -
import AVFoundation
let x: CGRect = AVMakeRect(aspectRatio: myImage.size, insideRect: sampleImageView.frame)
【讨论】：
-
是的，我完成了，但我在 y 上没有任何空间，但它返回为 40
-
这出乎意料，您是否尝试过使用没有约束的单个 imageView 的新视图控制器？
-
我在 uiview xib 上试过，在那个图像视图中，原点 x 值将变为 y，而原点 y 值将变为 x。我正在使用约束。
-
就像你说的那样，由于@Jack 的限制，这是一个问题
这是我的无 AVFoundation 解决方案。
首先这里是一个 CGSize 扩展，用于计算适合其他尺寸的尺寸：
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)
}
}
所以 OP 问题的解决方案归结为：
let resultSize = image.size.sizeThatFitsSize(imageView.bounds.size)
还有另一个扩展，用于在另一个矩形中拟合矩形（它利用上述 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
}
}
【讨论】：
如果您只知道图像视图的宽度并且图像的高度是动态的，那么您需要根据给定的宽度缩放图像的高度，以删除图像上方和下方的空白。使用here中的以下方法，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;
}
然后从你的 cellForRowAtIndexPath: 方法中调用它，如下所示：
UIImage *img = [dictImages objectForKey:yourImageKey]; // loaded the image
cell.imgView.image = [self imageWithImage:img scaledToWidth:self.view.frame.size.width];
【讨论】：
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
}
}
【讨论】：
Swift 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
}
}
【讨论】：
-
图片原点位置而不是Size怎么样？
请看@Paul-de-Lange 的回答，而不是这个
我在一个易于访问的变量中找不到任何东西，所以这是蛮力方法：
- (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);
}
【讨论】：
-
此代码不准确。它不能处理所有情况。例如，如果您有一个 2048 x 1536 的图像并尝试适应 514 x 402。当它应该将其缩放到宽度时，它将返回 402（高度）的缩放大小。我将
if ( a - x > b - y ) {更改为if ( a - x > b - y && (y/b * a) < x) {来修复它。他们的其他陈述也应该检查。 -
您好，先生，我发现这个 Anser 很有帮助，但您能帮我解决我的问题吗：stackoverflow.com/questions/22727615/…
对于 Swift 使用下面的代码
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)
}
并调用函数
imgFeed.sd_setImageWithURL(NSURL(string:"Your image URL")))
self.imageSizeAfterAspectFit(imgFeed)
【讨论】：
上述方法从未给出所需的值。由于纵横比保持相同的纵横比，我们只需要简单的数学来计算值
检测纵横比
CGFloat imageViewAspectRatio = backgroundImageView.bounds.size.width / backgroundImageView.bounds.size.height;
CGFloat imageAspectRatio = backgroundImageView.image.size.width / backgroundImageView.image.size.height;
CGFloat mulFactor = imageViewAspectRatio/imageAspectRatio;
获取新值
CGFloat newImageWidth = mulFactor * backgroundImageView.bounds.size.width;
CGFloat newImageHeight = mulFactor * backgroundImageView.bounds.size.height;
【讨论】：
我在 Swift 中使用以下内容：
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)
【讨论】：
我想使用AVMakeRectWithAspectRatioInsideRect() 不包括 AVFoundation 框架。
所以我实现了以下两个实用功能：
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：通过删除重复的分区在下方进行了优化。
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;
}
编辑结束
这采用给定的大小（第一个参数）并保持其纵横比。然后它在不违反纵横比的情况下尽可能地填充给定的边界（第二个参数）。
用这个来回答原来的问题：
// Using aspect fit, scale the image (size) to the image view's size.
CGSize sizeBeingScaledTo = CGSizeAspectFit(theImage.size, theImageView.frame.size);
注意图像如何决定纵横比，而图像视图决定要填充的大小。
非常欢迎反馈。
【讨论】：
-
如果你喜欢这样的事情，可以调整为使用
CGFloats。 -
优秀的答案。您还可以将其调整为以某个视图为中心，以使用 AspectFit 获取 UIImageView 内图像的实际 CGRect。我做了这样的事情：
CGSize imageSize = CGSizeAspectFit(imageView.image.size, imageView.frame.size); CGRect actualImageRect = CGRectMake(0, 0, imageSize.width, imageSize.height); actualImageRect.origin.x = imageView.center.x - imageSize.width / 2; actualImageRect.origin.y = imageView.center.y - imageSize.height / 2; -
谢谢，这是一个很棒的实用功能。
-
我已经包含了一个优化版本，可以删除重复的部门。现在想出一个无分支的等价物可能是一个有趣的挑战。 :)
我还想在应用纵横比后计算高度，以便能够计算表格视图单元格的高度。所以，我通过小数学实现了
ratio = width / height
高度会变成
height = width / ratio
所以代码 sn-p 将是
UIImage *img = [UIImage imageNamed:@"anImage"];
float aspectRatio = img.size.width/img.size.height;
float requiredHeight = self.view.bounds.size.width / aspectRatio;
【讨论】：
-
优雅。我在
UITableViewCell类中使用它，所以requiredHeight变为float requiredHeight = self.bounds.size.width / aspectRatio;。 -
你太棒了！这应该是公认的答案！
这是我针对相同问题的解决方案： https://github.com/alexgarbarev/UIImageView-ImageFrame
优点：
- 支持 UIViewContentMode 模式
- 可以分别查询比例和矩形
- 可以直接从 UIImageView 询问图像框架
【讨论】：
接受的答案非常复杂，并且在某些极端情况下会失败。我认为这个解决方案更加优雅：
- (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);
}
【讨论】：
也许不适合您的情况，但这种简单的方法在类似情况下解决了我的问题：
UIImageView *imageView = [[UIImageView alloc] initWithImage:bigSizeImage];
[imageView sizeToFit];
image view 执行 sizeToFit 后，如果您查询 imageView.frame.size，您将获得适合新图像尺寸的新 image view 尺寸。
【讨论】：
+(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;
}
【讨论】：