如何按比例缩放UIImageView?

很容易修复,一旦我找到文件!

 imageView.contentMode = UIViewContentModeScaleAspectFit;

我看过一些关于音阶类型的对话,所以我决定把 article regarding some of the most popular content mode scaling types .

我刚试过,UIImage不支持imageScaledToSize。

最后,我使用一个类别向UIImage添加了一个方法——这是我在Apple开发论坛上找到的一个建议。

在整个项目中。h-

@interface UIImage (Extras)
- (UIImage *)imageByScalingProportionallyToSize:(CGSize)targetSize;
@end;

@implementation UIImage (Extras)

- (UIImage *)imageByScalingProportionallyToSize:(CGSize)targetSize {

    UIImage *sourceImage = self;
    UIImage *newImage = nil;

    CGSize imageSize = sourceImage.size;
    CGFloat width = imageSize.width;
    CGFloat height = imageSize.height;

    CGFloat targetWidth = targetSize.width;
    CGFloat targetHeight = targetSize.height;

    CGFloat scaleFactor = 0.0;
    CGFloat scaledWidth = targetWidth;
    CGFloat scaledHeight = targetHeight;

    CGPoint thumbnailPoint = CGPointMake(0.0,0.0);

    if (CGSizeEqualToSize(imageSize, targetSize) == NO) {

        CGFloat widthFactor = targetWidth / width;
        CGFloat heightFactor = targetHeight / height;

        if (widthFactor < heightFactor) 
            scaleFactor = widthFactor;
        else
            scaleFactor = heightFactor;

        scaledWidth  = width * scaleFactor;
        scaledHeight = height * scaleFactor;

        // center the image

        if (widthFactor < heightFactor) {
            thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5; 
        } else if (widthFactor > heightFactor) {
            thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
        }
    }


    // this is actually the interesting part:

    UIGraphicsBeginImageContext(targetSize);

    CGRect thumbnailRect = CGRectZero;
    thumbnailRect.origin = thumbnailPoint;
    thumbnailRect.size.width  = scaledWidth;
    thumbnailRect.size.height = scaledHeight;

    [sourceImage drawInRect:thumbnailRect];

    newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    if(newImage == nil) NSLog(@"could not scale image");


    return newImage ;
}

@end;

imageView.contentMode = UIViewContentModeScaleAspectFill;
imageView.clipsToBounds = YES;

你可以试着做 imageView image . 以下代码未测试。

CGSize kMaxImageViewSize = {.width = 100, .height = 100};
CGSize imageSize = image.size;
CGFloat aspectRatio = imageSize.width / imageSize.height;
CGRect frame = imageView.frame;
if (kMaxImageViewSize.width / aspectRatio <= kMaxImageViewSize.height) 
{
    frame.size.width = kMaxImageViewSize.width;
    frame.size.height = frame.size.width / aspectRatio;
} 
else 
{
    frame.size.height = kMaxImageViewSize.height;
    frame.size.width = frame.size.height * aspectRatio;
}
imageView.frame = frame;

可以这样调整UIImage的大小

image = [UIImage imageWithCGImage:[image CGImage] scale:2.0 orientation:UIImageOrientationUp];

UIImage *image = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://farm4.static.flickr.com/3092/2915896504_a88b69c9de.jpg"]]];
UIImageView *imageView = [[UIImageView alloc] initWithImage:image]; 


//set contentMode to scale aspect to fit
imageView.contentMode = UIViewContentModeScaleAspectFit;

//change width of frame
//CGRect frame = imageView.frame;
//frame.size.width = 100;
//imageView.frame = frame;

//original lines that deal with frame commented out, yo.
imageView.frame = CGRectMake(10, 20, 60, 60);

...

//Add image view
[myView addSubview:imageView]; 

我发现在我的例子中,创建CGRect并指定所有的top、left、width和height值是调整位置的最简单方法,这是在表单元格中使用UIImageView。(仍需要添加代码以释放对象)

Aspect Fill 并检查 Clip Subviews

imageView.contentMode = .ScaleAspectFill
imageView.clipsToBounds = true;

设置您的 UIimageview

对于Swift:

self.imageViews.contentMode = UIViewContentMode.ScaleToFill

#import <Foundation/Foundation.h>

@interface UIImageView (Scale)

-(void) scaleAspectFit:(CGFloat) scaleFactor;

@end

UIImageView+Scale.m:

#import "UIImageView+Scale.h"

@implementation UIImageView (Scale)


-(void) scaleAspectFit:(CGFloat) scaleFactor{

    self.contentScaleFactor = scaleFactor;
    self.transform = CGAffineTransformMakeScale(scaleFactor, scaleFactor);

    CGRect newRect = self.frame;
    newRect.origin.x = 0;
    newRect.origin.y = 0;
    self.frame = newRect;
}

@end

我用的是代码.whereimageCoverView是UIView持有UIImageView

if (image.size.height<self.imageCoverView.bounds.size.height && image.size.width<self.imageCoverView.bounds.size.width)
{
    [self.profileImageView sizeToFit];
    self.profileImageView.contentMode =UIViewContentModeCenter
}
else
{
    self.profileImageView.contentMode =UIViewContentModeScaleAspectFit;
}

如果这里提出的解决方案对您不起作用,并且您的图像资产实际上是一个PDF,请注意XCode实际上对待PDF的方式与对待图像文件的方式不同。尤其是,它似乎无法按比例正确填充PDF:而是以平铺结束。这让我抓狂,直到我发现问题是PDF格式。转换成JPG,你应该很好去。

通常我对我的应用程序使用这种方法( 斯威夫特2.x

// Resize UIImage
func resizeImage(image:UIImage, scaleX:CGFloat,scaleY:CGFloat) ->UIImage {
    let size = CGSizeApplyAffineTransform(image.size, CGAffineTransformMakeScale(scaleX, scaleY))
    let hasAlpha = true
    let scale: CGFloat = 0.0 // Automatically use scale factor of main screen

    UIGraphicsBeginImageContextWithOptions(size, !hasAlpha, scale)
    image.drawInRect(CGRect(origin: CGPointZero, size: size))

    let scaledImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return scaledImage
}

image.center = [[imageView window] center];

这是你如何轻松地缩放它的方法。

它可以在2.x中与模拟器和iPhone一起工作。

UIImage *thumbnail = [originalImage _imageScaledToSize:CGSizeMake(40.0, 40.0) interpolationQuality:1];