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拍摄图像（具有任何宽高比和任何分辨率）并且我希望它适合边框，因此图片不会超过它们，但它可以根据需要缩小它们。 （图中标记为红色）：
现在图像正确地适合所需的大小，但我有两个担忧：1。UIImageView不等于调整大小的图像的大小，因此留下红色背景（我不想要那样）2。如果图像较小我的UIImageView的高度没有调整到更小，它保持相同的高度。
这是我的代码，我知道它的错误：
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;
那么我如何动态地改变UIImageView.image的大小，而不是整个UIImageView的大小，从而使其大小完全可以调整其内容。任何帮助将不胜感激，谢谢！
当您获得调整大小的图像Get width of a resized image after UIViewContentModeScaleAspectFit的宽度和高度时，您可以调整imageView的大小：
imageView.frame = CGRectMake(0, 0, resizedWidth, resizedHeight);
imageView.center = imageView.superview.center;
我没有检查它是否有效，但我认为一切都应该没问题
- (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;
}
这是使用扩展的Rajneesh071答案的Swift等价物
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
}
}
用法：
let image = UIImage(named: "Icon")
item.icon = image?.scaleToSize(CGSize(width: 30.0, height: 30.0))
使用下面的类别，然后将Quartz中的边框应用到您的图像中：
[yourimage.layer setBorderColor:[[UIColor whiteColor] CGColor]];
[yourimage.layer setBorderWidth:2];
类别：UIImage + AutoScaleResize.h
#import <Foundation/Foundation.h>
@interface UIImage (AutoScaleResize)
- (UIImage *)imageByScalingAndCroppingForSize:(CGSize)targetSize;
@end
的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
如果你有图像的大小，为什么不设置图像视图的frame.size这个大小？
编辑 - -
好的，所以看到你的评论我建议：
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
}
此代码会将图像视图的大小调整为其图像比例，并将图像视图定位到与“默认”位置相同的中心。
PS：我希望你设置imageView.layer.shouldRasterise = YES和imageView.layer.rasterizationScale = [UIScreen mainScreen].scale;
如果您正在使用CALayer阴影效果;）它将极大地提高您的UI性能。
我想你想要的是一个不同的content mode。尝试使用UIViewContentModeScaleToFill。如果需要，这将通过更改内容的宽高比来缩放内容以适合您的UIImageView的大小。
请查看官方文档中的content mode部分，以更好地了解可用的不同内容模式（用图像说明）。
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];
}];
}