SwiftImageReadWrite

A basic Swift microframework of routines for doing basic importing/exporting of CGImage and NSImage/UIImage type images.

Why?

Sometimes all you need is to be able load and save basic image data in different formats. This framework provides a basic wrapper around the common use cases.

Apple’s built in image types are incredibly capable but can be quite verbose to do basic import and export to different image file types. It’s also somewhat tricky to get basic export correct, so this framework abstracts that away with a type-safe, format safe way.

There are also differences between macOS and the rest of the Apple ecosystem when it comes to converting platform images and this library abstracts those differences away. The same API will work on macOS/iOS/watchOS and tvOS.

It also provides Codable wrapper implementations for CGImage/NSImage/UIImage (CGImageCodable, PlatformImageCodable) to allow easy embedding of images in your Codable objects.

Supported types

• PNG
• JPEG
• TIFF
• GIF
• HEIC
• PDF
• SVG

representation

All the encoding/conversion calls are wrapped inside representation on an image object. This was done to avoid clashing with the platform image calls of similar names.

For example :-

let image = UIImage(/* some image */)
let pngData = try image.representation.png(scale: 2)

let image = CGImage(/* some image */)
let pngData = try image.representation.pdf(size: CGSize(width: 300, height: 300))

Basic examples

CGImage

// Load a CGImage from raw data
let image = try CGImage.load(imageData: data)

// Export the image as JPG data
let jpegData = try image.representation.jpeg(scale: 3, compression: 0.65, excludeGPSData: true))

// Export the image as PNG data
let pngData = try image.representation.png(scale: 2)

NSImage/UIImage

// Load a CGImage from raw data
let cgImage = CGImage.load(imageData: data)

// Convert to an NSImage (or UIImage)
let nsImage = cgImage.platformImage(scale: 2)

// Generate a PDF representation of the pdf
let pdf = try nsImage.representation.pdf()

SwiftUI

// Load a CGImage from raw data
let cgImage = CGImage.load(imageData: data)

// Create a SwiftUI image with this image
let swiftUIImage = cgImage.imageUI(scale: 2, label: Text("My Image"))

Limitations

• NSImage supports multiple image representations within a single image. These routines only deal with a single representation, so an image with multiple stored representations will only ever deal with the ‘best’ representation.

License

MIT License

Copyright (c) 2023 Darren Ford

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