将 UIImage 裁剪到中心正方形 [英] Crop UIImage to center square

问题描述

我得到分辨率为 1920x1080 的图像.我试图将它们裁剪到中心正方形区域(即中心的 1080x1080 正方形).该决议将来可能会发生变化.可以用这种方式裁剪图像吗?我已经尝试了一些发布在 SO 上的东西，但是如果我尝试裁剪然后居中，我总是会得到一个 660x1080 的图像.这是一张描绘我想要实现的目标的图像.

I get images that are in 1920x1080 resolution. I am attempting to crop them to the center square area (ie 1080x1080 square in the center). The resolution may change in the future. Would it be possible to crop the image this way? I have tried a couple things posted on SO, but I always get an image that is 660x1080 if I try to crop then center. Here is an image depicting what I want to achieve.

基本上红色是原始的，绿色是我想要的，黄色只是显示 mixX 和 midY 线.

Basically the red is original, green is what I want, and yellow is just showing mixX and midY lines.

我试过的代码.

func imageByCroppingImage(image: UIImage, toSize size: CGSize) -> UIImage{
    let newCropWidth: CGFloat?
    let newCropHeight: CGFloat?

    if image.size.width < image.size.height {
        if image.size.width < size.width {
            newCropWidth = size.width
        } else {
            newCropWidth = image.size.width
        }
        newCropHeight = (newCropWidth! * size.height) / size.width
    } else {
        if image.size.height < size.height {
            newCropHeight = size.height
        } else {
            newCropHeight = image.size.height
        }
        newCropWidth = (newCropHeight! * size.width) / size.height
    }

    let x = image.size.width / 2.0 - newCropWidth! / 2.0
    let y = image.size.height / 2.0 - newCropHeight! / 2.0

    let cropRect = CGRect(x: x, y: y, width: newCropWidth!, height: newCropHeight!)
    let imageRef = image.cgImage!.cropping(to: cropRect)

    let cropped = UIImage(cgImage: imageRef!, scale: 1.0, orientation: .right)
    return cropped
}

然后我将该方法传递给 CGSize(1080, 1080).我得到的图像是 660、1080.有什么想法吗?

And then I pass that method a CGSize(1080, 1080). I get an image that is 660, 1080. Any thoughts?

目的是裁剪图像，而不仅仅是居中显示.

推荐答案

您可以使用我在此答案 没有UIBezierPath(ovalIn:breadthRect).addClip()

You can use the same approach I used in this answer without the line UIBezierPath(ovalIn: breadthRect).addClip()

extension UIImage {
    var isPortrait:  Bool    { size.height > size.width }
    var isLandscape: Bool    { size.width > size.height }
    var breadth:     CGFloat { min(size.width, size.height) }
    var breadthSize: CGSize  { .init(width: breadth, height: breadth) }
    func squared(isOpaque: Bool = false) -> UIImage? {
        guard let cgImage = cgImage?
            .cropping(to: .init(origin: .init(x: isLandscape ? ((size.width-size.height)/2).rounded(.down) : 0,
                                              y: isPortrait  ? ((size.height-size.width)/2).rounded(.down) : 0),
                                size: breadthSize)) else { return nil }
        let format = imageRendererFormat
        format.opaque = isOpaque
        return UIGraphicsImageRenderer(size: breadthSize, format: format).image { _ in
            UIImage(cgImage: cgImage, scale: 1, orientation: imageOrientation)
            .draw(in: .init(origin: .zero, size: breadthSize))
        }
    }
}

<小时>

let imageURL = URL(string: "http://i.stack.imgur.com/Xs4RX.jpg")!
let image = UIImage(data: try! Data(contentsOf: imageURL))!

let squared = image.squared()

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