Question

我想对JPEG图像进行矩形裁剪。我有以下代码将创建重复的图像。它使用一个NSImage。我不知道如何创建裁剪的图像。

   func crop(index: Int)  {
        let croppedImageUrl = ...
        let imageUrl = ...

        // Create a cropped image.
        let data = try? Data(contentsOf: imageUrl)
        let image = NSImage(data: data!)
        let tiffRepresentation = (image?.tiffRepresentation)!
        let bitmap = NSBitmapImageRep(data: tiffRepresentation)
        let representation = bitmap?.representation(using: NSBitmapImageRep.FileType.jpeg, properties: [:])
        do {
            try representation?.write(to: croppedImageUrl, options: [.withoutOverwriting])
        } catch let error as NSError {
            print(error.localizedDescription)
        }
    }

Answer 1

这可以帮助您裁剪图像

func crop() -> UIImage? {
    let imageUrl = URL(string: "imageUrl")!
    let data = try! Data(contentsOf: imageUrl)
    let image = UIImage(data: data)!

    // Crop rectangle
    let width = min(image.size.width, image.size.height)
    let size = CGSize(width: width, height: width)

    // If you want to crop center of image
    let startPoint = CGPoint(x: (image.size.width - width) / 2, y: (image.size.height - width) / 2)

    UIGraphicsBeginImageContextWithOptions(size, false, 0)

    image.draw(in: CGRect(origin: startPoint, size: size))

    let croppedImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return croppedImage
}

Answer 2

类似...

func crop(nsImage: NSImage,rect: CGRect) -> NSImage {  
    let cgImage = (nsImage?.cgImage(forProposedRect: nil, context: nil, hints: nil)?.cropping(to: rect))!

    let size = NSSize(width: rect.width, height: rect.height)
    return NSImage(cgImage: cgImage, size: size)
}

抱歉，未编译此代码片段，但通用方法在我的代码中起作用。如果可能的话，做为NSImage的扩展可能做得更好。

如何从URL，Swift，MacOS裁剪Jpeg图像

2 个答案: