[英]Swift on MacOS - How to save NSImage to disk
我有以下代码工作:
let myImage = NSImage(named: "my-image.png")
filter.setValue(myImage, forKey: kCIInputImageKey)
filter.setValue(0.5, forKey: kCIInputIntensityKey)
let resultImage = filter.outputImage
如何将过滤后的图像(作为 PNG)保存到磁盘? 请注意,这是 UIImage 不可用的 MacOS 版本(Xcode 抛出:尝试导入时没有这样的模块“UIImage”)
您可以从ciimage过滤器结果创建Core Image Context和createCGImage。 你可以这样做:
import Cocoa
class ViewController: NSViewController {
override func viewDidLoad() {
super.viewDidLoad()
let context = CIContext()
let desktopURL = FileManager.default.urls(for: .desktopDirectory, in: .userDomainMask).first!
guard
let filter = CIFilter(name: "CISepiaTone"),
let imageURL = Bundle.main.url(forResource: "my-image", withExtension: "png"),
let ciImage = CIImage(contentsOf: imageURL)
else { return }
filter.setValue(ciImage, forKey: kCIInputImageKey)
filter.setValue(0.5, forKey: kCIInputIntensityKey)
guard let result = filter.outputImage, let cgImage = context.createCGImage(result, from: result.extent)
else { return }
let destinationURL = desktopURL.appendingPathComponent("my-image.png")
let nsImage = NSImage(cgImage: cgImage, size: ciImage.extent.size)
if nsImage.pngWrite(to: destinationURL, options: .withoutOverwriting) {
print("File saved")
}
}
}
您将需要这些扩展来获取png表示数据以将结果图像写入磁盘:
extension NSImage {
var pngData: Data? {
guard let tiffRepresentation = tiffRepresentation, let bitmapImage = NSBitmapImageRep(data: tiffRepresentation) else { return nil }
return bitmapImage.representation(using: .png, properties: [:])
}
func pngWrite(to url: URL, options: Data.WritingOptions = .atomic) -> Bool {
do {
try pngData?.write(to: url, options: options)
return true
} catch {
print(error)
return false
}
}
}
这个扩展:
public extension NSImage {
func save(to url: URL, format: NSBitmapImageRep.FileType, props: [NSBitmapImageRep.PropertyKey : Any] ) -> Result<URL, Error> {
return self.representations.first
.asNonOptional
.map { $0 as? NSBitmapImageRep }
.flatMap { data -> R<NSBitmapImageRep> in data.asNonOptional }
.map { $0.representation(using: .jpeg, properties: props) }
.flatMap{ $0.asNonOptional }
.map { try? $0.write(to: url) }
.map { $0.asNonOptional }
.map { _ in url}
}
}
public extension Optional {
var asNonOptional : R<Wrapped> {
if let val = self {
return .success(val)
} else {
return .failure(CustomError("nil for optional value of type <\(Wrapped.self)>"))
}
}
}
public func CustomError(_ msg: String, code: Int = 0) -> Error {
NSError(code: code, message: msg)
}
适用于最需要的文件格式并支持任何需要的属性。
用法:
_ = someImage.write(to: url, format: .png, props: [.compressionFactor : NSNumber(floatLiteral: 1.0)])
_ = someImage.write(to: url, format: .jpeg, props: [.compressionFactor : NSNumber(floatLiteral: 1.0)])
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