ios 调整 UIImage 大小并改变 UIImageView 的大小

Resize UIImage and change the size of UIImageView

提问by Sergey Grischyov

I have this UIImageViewand I have the values of its max height and max width. What I want to achieve is that I want to take the image (with any aspect ratio and any resolution) and I want it to fit in the borders, so the picture does not exceedthem, but it can shrink them as it wants. (marked red in the picture):

我有这个UIImageView，我有它的最大高度和最大宽度的值。我想要实现的是我想要拍摄图像（具有任何纵横比和任何分辨率）并且我希望它适合边界，因此图片不会超过它们，但它可以根据需要缩小它们。（图中红色标记）：

Right now the image fits the necessary size properly, but I have 2 worries: 1. The UIImageViewis not equal the size of the resized image, thus leaving red background (and I don't want that) 2. If the image is smaller that the height of my UIImageViewit is not resized to be smaller, it stays the same height.

现在图像适合所需的大小，但我有两个担心： 1.UIImageView不等于调整大小的图像的大小，从而留下红色背景（我不想要） 2. 如果图像较小我的UIImageView它的高度没有调整为更小，它保持相同的高度。

Here's my code and I know its wrong:

这是我的代码，我知道它是错误的：

UIImage *actualImage = [attachmentsArray lastObject];
UIImageView *attachmentImageNew = [[UIImageView alloc] initWithFrame:CGRectMake(5.5, 6.5, 245, 134)];
attachmentImageNew.image = actualImage;
attachmentImageNew.backgroundColor = [UIColor redColor];
attachmentImageNew.contentMode = UIViewContentModeScaleAspectFit;

So how do I dynamically change the size not only of the UIImageView.image, but of the whole UIImageView, thus making its size totally adjustable to its content. Any help would be much appreciated, thanks!

那么我如何不仅动态地改变 . 的大小UIImageView.image，而且还改变整个UIImageView. 任何帮助将不胜感激，谢谢！

回答by Mikhail

When you get the width and height of a resized image Get width of a resized image after UIViewContentModeScaleAspectFit, you can resize your imageView:

当您获取调整大小的图像的宽度和高度时，在 UIViewContentModeScaleAspectFit 之后获取调整大小的图像的宽度，您可以调整 imageView 的大小：

imageView.frame = CGRectMake(0, 0, resizedWidth, resizedHeight);
imageView.center = imageView.superview.center;

I haven't checked if it works, but I think all should be OK

我还没有检查它是否有效，但我认为一切都应该没问题

回答by Rajneesh071

- (UIImage *)image:(UIImage*)originalImage scaledToSize:(CGSize)size
{
    //avoid redundant drawing
    if (CGSizeEqualToSize(originalImage.size, size))
    {
        return originalImage;
    }

    //create drawing context
    UIGraphicsBeginImageContextWithOptions(size, NO, 0.0f);

    //draw
    [originalImage drawInRect:CGRectMake(0.0f, 0.0f, size.width, size.height)];

    //capture resultant image
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    //return image
    return image;
}

回答by JoeGalind

This is the Swift equivalent for Rajneesh071's answer, using extensions

这是 Rajneesh071 答案的 Swift 等价物，使用扩展

UIImage {
  func scaleToSize(aSize :CGSize) -> UIImage {
    if (CGSizeEqualToSize(self.size, aSize)) {
      return self
    }

    UIGraphicsBeginImageContextWithOptions(aSize, false, 0.0)
    self.drawInRect(CGRectMake(0.0, 0.0, aSize.width, aSize.height))
    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return image
  }
}

Usage:

用法：

let image = UIImage(named: "Icon")
item.icon = image?.scaleToSize(CGSize(width: 30.0, height: 30.0))

回答by CainaSouza

Use the category below and then apply border from Quartz into your image:

使用下面的类别，然后将 Quartz 的边框应用到您的图像中：

[yourimage.layer setBorderColor:[[UIColor whiteColor] CGColor]];
[yourimage.layer setBorderWidth:2];

The category: UIImage+AutoScaleResize.h

类别：UIImage+AutoScaleResize.h

#import <Foundation/Foundation.h>

@interface UIImage (AutoScaleResize)

- (UIImage *)imageByScalingAndCroppingForSize:(CGSize)targetSize;

@end

UIImage+AutoScaleResize.m

UIImage+AutoScaleResize.m

#import "UIImage+AutoScaleResize.h"

@implementation UIImage (AutoScaleResize)

- (UIImage *)imageByScalingAndCroppingForSize:(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; // scale to fit height
        }
        else
        {
            scaleFactor = heightFactor; // scale to fit width
        }

        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;
            }
        }
    }

    UIGraphicsBeginImageContext(targetSize); // this will crop

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

    [sourceImage drawInRect:thumbnailRect];

    newImage = UIGraphicsGetImageFromCurrentImageContext();

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

    //pop the context to get back to the default
    UIGraphicsEndImageContext();

    return newImage;
}

@end

回答by Baldoph

If you have the size of the image, why don't you set the frame.sizeof the image view to be of this size?

如果您有图像的大小，为什么不frame.size将图像视图的设置为这个大小？

EDIT----

编辑 - -

Ok, so seeing your comment I propose this:

好的，所以看到您的评论，我建议：

UIImageView *imageView;
//so let's say you're image view size is set to the maximum size you want

CGFloat maxWidth = imageView.frame.size.width;
CGFloat maxHeight = imageView.frame.size.height;

CGFloat viewRatio = maxWidth / maxHeight;
CGFloat imageRatio = image.size.height / image.size.width;

if (imageRatio > viewRatio) {
    CGFloat imageViewHeight = round(maxWidth * imageRatio);
    imageView.frame = CGRectMake(0, ceil((self.bounds.size.height - imageViewHeight) / 2.f), maxWidth, imageViewHeight);
}
else if (imageRatio < viewRatio) {
    CGFloat imageViewWidth = roundf(maxHeight / imageRatio);
    imageView.frame = CGRectMake(ceil((maxWidth - imageViewWidth) / 2.f), 0, imageViewWidth, maxHeight);
} else {
    //your image view is already at the good size
}

This code will resize your image view to its image ratio, and also position the image view to the same centre as your "default" position.

此代码会将您的图像视图调整为其图像比例，并将图像视图定位到与“默认”位置相同的中心。

PS: I hope you're setting imageView.layer.shouldRasterise = YESand imageView.layer.rasterizationScale = [UIScreen mainScreen].scale;

PS：我希望你设置imageView.layer.shouldRasterise = YES和imageView.layer.rasterizationScale = [UIScreen mainScreen].scale;

if you're using CALayer shadow effect ;) It will greatly improve the performance of your UI.

如果您使用 CALayer 阴影效果 ;) 它会大大提高您的 UI 的性能。

回答by tiguero

I think what you want is a different content mode. Try using UIViewContentModeScaleToFill. This will scale the content to fit the size of ur UIImageView by changing the aspect ratio of the content if necessary.

我想你想要的是不同的content mode。尝试使用UIViewContentModeScaleToFill. 如有必要，这将通过更改内容的纵横比来缩放内容以适合您的 UIImageView 的大小。

Have a look to the content modesection on the official doc to get a better idea of the different content mode available (it is illustrated with images).

查看content mode官方文档上的部分，以更好地了解可用的不同内容模式（用图像说明）。

回答by Gami Nilesh

   if([[SDWebImageManager sharedManager] diskImageExistsForURL:[NSURL URLWithString:@"URL STRING1"]])
   {
       NSString *key = [[SDWebImageManager sharedManager] cacheKeyForURL:[NSURL URLWithString:@"URL STRING1"]];

       UIImage *tempImage=[self imageWithImage:[[SDImageCache sharedImageCache] imageFromDiskCacheForKey:key] scaledToWidth:cell.imgview.bounds.size.width];
       cell.imgview.image=tempImage;

   }
   else
   {
       [cell.imgview sd_setImageWithURL:[NSURL URLWithString:@"URL STRING1"] placeholderImage:nil completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL)
        {
            UIImage *tempImage=[self imageWithImage:image scaledToWidth:cell.imgview.bounds.size.width];
            cell.imgview.image=tempImage;
//                [tableView beginUpdates];
//                [tableView endUpdates];

        }];
   }