我正在以“Aspect Fit”模式将图像加载到图像视图中。 我需要知道我的图像被缩放到的大小。 请帮忙。
我正在以“Aspect Fit”模式将图像加载到图像视图中。 我需要知道我的图像被缩放到的大小。 请帮忙。
我想在不包含AVFoundation框架的情况下使用AVMakeRectWithAspectRatioInsideRect()
。
因此,我实现了以下两个工具函数:
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:通过删除重复的除法进行了优化。
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
这个函数接受一个给定的大小(第一个参数),并保持其宽高比。然后尽可能填充给定的边界(第二个参数),而不违反宽高比。
使用此函数来回答原始问题:
// Using aspect fit, scale the image (size) to the image view's size.
CGSize sizeBeingScaledTo = CGSizeAspectFit(theImage.size, theImageView.frame.size);
请注意图像决定了宽高比,而图像视图则决定要填充的大小。非常欢迎反馈。请查看@Paul-de-Lange的答案,而不是这个
我在容易访问的变量中找不到任何内容,因此这里是一种蛮力方法:
- (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);
}
if ( a - x > b - y ) {
改为 if ( a - x > b - y && (y/b * a) < x) {
来修复它。其他语句也应该被检查。 - renaun这个简单的函数将计算纵横比适应后的图像尺寸:
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)
}
}
Objective 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);
}
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
}
}
我也想在应用宽高比之后计算高度,以便能够计算表视图单元格的高度。所以,我通过一点数学方法实现了这一点。
ratio = width / height
并且高度会变成
height = width / ratio
因此代码片段应为
UIImage *img = [UIImage imageNamed:@"anImage"];
float aspectRatio = img.size.width/img.size.height;
float requiredHeight = self.view.bounds.size.width / aspectRatio;
UITableViewCell
类中使用它,所以requiredHeight
变成了float requiredHeight = self.bounds.size.width / aspectRatio;
。 - oyalhi如果使用Swift,请使用下面的代码
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)
}
调用函数
imgFeed.sd_setImageWithURL(NSURL(string:"Your image URL")))
self.imageSizeAfterAspectFit(imgFeed)
UIImageView *imageView = [[UIImageView alloc] initWithImage:bigSizeImage];
[imageView sizeToFit];
在image view执行sizeToFit之后,如果您查询imageView.frame.size
,您将获得适合新图像尺寸的新图像视图大小。
Swift 4: .aspectFit
图像框架为 -
import AVFoundation
let x: CGRect = AVMakeRect(aspectRatio: myImage.size, insideRect: sampleImageView.frame)
let x: CGRect = AVMakeRect(aspectRatio: myImage.size, insideRect: sampleImageView.frame)
+(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;
}
[imageView setFrame:AVMakeRectWithAspectRatioInsideRect(image.size, imageView.frame)]
。 - gregAVMakeRectWithAspectRatioInsideRect()
的实用函数。 - Timo