UIImageView、setClipsToBounds 以及我的图像是如何失去理智的

UIImageView, setClipsToBounds and how my images are losing their head(UIImageView、setClipsToBounds 以及我的图像是如何失去理智的)

问题描述

我正在开发一个 iOS 4 应用程序.

I'm developing an iOS 4 application.

我在 UITableViewCell 上的 UIImageView 上使用此代码:

I'm using this code on an UIImageView on an UITableViewCell:

cell.photo.contentMode = UIViewContentModeScaleAspectFill;
[cell.photo setClipsToBounds:YES];

我的图像比宽高，当我设置 UIViewContentModeScaleAspectFill 时，图像被缩放以适应 UIImageView 宽度的宽度.这样做，图像变得比 UIImageView 更大，我在 UIImageView 之外看到它.

My images are taller than wide, and when I set UIViewContentModeScaleAspectFill, images are scaled to fit width with UIImageView width. Doing this, the image gets bigger that UIImageView and I see it outside UIImageView.

然后，我需要使用 setClipsToBounds:YES 来不允许这样做，但现在我所有的图像都失去了理智.

Then, I need to use setClipsToBounds:YES to don't allow this, but now all my images lose their head.

有什么方法可以使用 UIViewContentModeScaleAspectFill 和左上角图像左上角 UIImageView 角?如果我需要失去一部分形象，我宁愿失去它的脚而不是它的头.

Is there any way to use UIViewContentModeScaleAspectFill and center top left image corner with top left UIImageView corner? If I need to lose a part of image, I prefer to lose its feet that its head.

更新

我正在使用 sdWebImage 框架，并且我使用了 Vadim Yelagin 的答案，这是我现在的代码:

I'm using sdWebImage framework and I have used Vadim Yelagin answer and this is my code now:

[cell.photo setImageWithURL:[NSURL URLWithString:entry.photo]
               placeholderImage:[UIImage imageNamed:@"placeholder.png"]
                        success:^(UIImage *image) {
                            CGFloat scaleX = cell.photoBorder.bounds.size.width / image.size.width;
                            CGFloat scaleY = cell.photoBorder.bounds.size.height / image.size.height;
                            CGFloat scale = MAX(scaleX, scaleY);
                            cell.photo.frame = CGRectMake(0, 0, image.size.width * scale, image.size.height * scale);
                            cell.photo.image = image;
                        } 
                        failure:nil];

我必须等待加载所有图像并重新加载在 UITableView 周围移动才能在正确的单元格上看到正确的图像(这是因为图像被缓存并且加载速度更快).

I have to wait to get all images loaded and reload move around UITableView to see the right image on the right cell (this is because images are cached and it loads faster).

而不是使用 cell.photo.frame 和 cell.photo.image 我需要传递到块 indexPath.row 以获得正确的细胞.

Instead using cell.photo.frame and cell.photo.image I need to pass to block indexPath.row to get the right cell.

我可以向 UIImageView+WebCache 添加一个新方法:

I could add a new method to UIImageView+WebCache:

- (void)setImageWithURL:(NSURL *)url placeholderImage:(UIImage *)placeholder success:(void (^)(UIImage *image, NSInteger row))success failure:(void (^)(NSError *error))failure;
{
    [self setImageWithURL:url placeholderImage:placeholder options:0 success:success failure:failure];
}

但如果我这样做，我会在这里收到错误:

But if I do that, I get an error here:

[self setImageWithURL:url placeholderImage:placeholder options:0 success:success failure:failure];

因为现在成功不是类型 (void (^)(UIImage *image))

Because now success isn't of type (void (^)(UIImage *image))

你知道我该如何解决这个问题吗?

Do you know how can I fix this problem?

推荐答案

Afaik，最简单的方法是根据图像的大小和您希望它适合的框架手动计算 imageView 的框架.

Afaik, the easiest way is to calculate the imageView's frame manually from the size of the image and the frame you want it to fit in.

使用您当前为 imageView 指定的框架创建一个视图，将 imageView 设为其子视图.设置 view.clipsToBounds = YES.

Create a view with the frame you're currently specifying for your imageView, make the imageView its subview. Set view.clipsToBounds = YES.

然后，当您分配图像时，请执行以下操作

Then when you assign an image, do something like

CGFloat scaleX = view.bounds.size.width / image.size.width;
CGFloat scaleY = view.bounds.size.height / image.size.height;
CGFloat scale = MAX(scaleX, scaleY);
imageView.frame = CGRectMake(0, 0, image.size.width * scale, image.size.height * scale);
imageView.image = image;

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