ColorPaletteCodable

A color palette reader/editor/writer package for iOS, macOS, macCatalyst, tvOS, watchOS and Linux.

Supports the following color palette formats

Adobe Swatch Exchange (.ase)
Adobe Photoshop Color Swatch (.aco)
Adobe Color Table (.act)
Adobe Color Book (.acb) (read only)
NSColorList (.clr) (macOS only)
RGB text files (.rgb)
RGBA text files (.rgba)
GIMP palette files (.gpl)
Paint Shop Pro files (.pal, .psppalette)
Microsoft RIFF palette files (.pal) (read only)
SketchPalette files (.sketchpalette)
CorelDraw/Adobe Illustrator xml palette (.xml)
JSON encoded color files (.jsoncolorpalette) ColorPaletteCodable internal file format
Hex Color Palette (text file with delimited hexadecimal color strings) (.hex)

Why?

I wanted to be able to read and write .ase palette files in my Swift app. This then extended to .aco Adobe Photoshop Color Swatch files. Which then expanded to other types :-)

Some features :-

Named palettes
Named colors
Multiple named groups of colors within a single palette
Colorspace support (RGB, CMYK, Gray) with conversion capabilities
Encoding/Decoding of all supported palette coder types
Includes a cross-platorm, human readable, palette coder (json utf8 format)
Integrated pasteboard support for macOS/iOS
Simple image generation for an group of colors

API

Type	Description
`PAL.Palette`	The full representation of a palette
`PAL.Group`	An optionally named collection of colors
`PAL.Color`	An optionally named color

Coders

Type	Description
`PAL.Coder.ACB`	Adobe Color Book (.acb)
`PAL.Coder.ACO`	Adobe Photoshop Color Swatch (.aco)
`PAL.Coder.ACT`	Adobe Color Table (.act)
`PAL.Coder.ASE`	Adobe Swatch Exchange (.ase)
`PAL.Coder.CLR`	NSColorList (.clr) (macOS only)
`PAL.Coder.GIMP`	GIMP palette files (.gpl)
`PAL.Coder.HEX`	Hex Color Palette (`.hex`)
`PAL.Coder.JSON`	JSON encoded palette (.jsoncolorpalette)
`PAL.Coder.PaintShopPro`	Paint Shop Pro palette (.pal;.psppalette)
`PAL.Coder.RGB`	RGB text files (.rgb)
`PAL.Coder.RGBA`	RGB(A) text files (.rgba)
`PAL.Coder.RIFF`	Microsoft RIFF palette (.pal)
`PAL.Coder.SketchPalette`	Sketch Palette (.sketchpalette)
`PAL.Coder.XMLPalette`	CorelDraw/Adobe Illustrator Palette (.xml)

Tasks

Decode a palette file

do {
   let myFileURL = URL(fileURL: ...)
   let palette = try PAL.Palette.Decode(from: myFileURL)
   
   // do something with 'palette'
}
catch {
   // Do something with 'error'
}

Build a palette and generate an ASE binary representation

do {
   // Build a palette
   var palette = PAL.Palette()
   let c1 = try PAL.Color.rgb(name: "red",   1, 0, 0)
   let c2 = try PAL.Color.rgb(name: "green", 0, 1, 0)
   let c3 = try PAL.Color.rgb(name: "blue",  0, 0, 1)
   palette.colors.append(contentsOf: [c1, c2, c3])

   // Generate a simple image from the colors
   let image = try PAL.Image.Image(colors: [c1, c2, c3], size: CGSize(width: 100, height: 25))

   // Create an ASE coder
   let coder = PAL.Coder.ASE()

   // Get the .ase format data
   let rawData = try coder.encode(palette)
   
   // Do something with 'rawData' (like write to a file for example)
}
catch {
   // Do something with 'error'
}

Read an ACO file, write an ASE file

do {
   let acoFileURL = URL(fileURL: ...)
   let coder = PAL.Coder.ACO()
   var palette = try coder.decode(from: acoFileURL)
   
   // do something with 'palette'
   
   // re-encode the palette to an ASE format
   let encoder = PAL.Coder.ASE()
   let rawData = try encoder.encode(palette) 
}
catch {
   // Do something with 'error'
}

QuickLook support (macOS 12+ only)

This package also includes a Quicklook Plugin for palette files. macOS 12 has changed the was quicklook plugins work, by creating an .appex extension (which is the quicklook plugin) embedded within an application.

In the Quicklook subfolder you’ll find an xcodeproj which you can use to build the application Palette Viewer which contains the QuickLook plugin.

For the plugin to register, you need to run the application. After the first run the QuickLook plugin will be registered.

Palette viewer

Palette Viewer allows you to view the contents of

Adobe Color Book files (.acb)
Adobe Photoshop Color Swatch files (.aco)
Adobe Color Table files (.act)
Adobe Swatch Exchange files (.ase)
Apple ColorList files (.clr)
RGB/RGBA hex encoded text files (.txt)
GIMP text files (.gpl)
JASC Paint Shop Pro (Corel) text files (.pal, .psppalette)
Microsoft RIFF Palette (.pal)
Sketch palette (.sketchpalette)
CorelDraw/Adobe Illustrator XML palette (.xml)
Hex delimited color palette (.hex)

You can drag colors out of the preview window into applications that support dropping of NSColor instances.

You can also save the palette to a new format (eg. saving a gimp .gpl format to an Adobe .aco format)

Palette format encoding/decoding limitations

	File Type	Named Colors?	Named palette?	Color Groups?	ColorType Support?	Supports Colorspaces?
`PAL.Coder.ACB`	Binary	✅	❌	❌	❌	✅
`PAL.Coder.ACO`	Binary	✅	❌	❌	❌	✅
`PAL.Coder.ACT`	Binary	❌	❌	❌	❌	RGB only
`PAL.Coder.ASE`	Binary	✅	❌	✅	✅	✅
`PAL.Coder.CLR`	Binary (macOS only)	✅	❌	❌	❌	✅
`PAL.Coder.GIMP`	Text	✅	✅	❌	❌	RGB only
`PAL.Coder.HEX`	Text	❌	❌	❌	❌	RGB only
`PAL.Coder.JSON`	JSON Text	✅	✅	✅	✅	✅
`PAL.Coder.PaintShopPro`	Text	❌	❌	❌	❌	RGB only
`PAL.Coder.RGB/A`	Text	✅	❌	❌	❌	RGB only
`PAL.Coder.RIFF`	Binary	❌	❌	❌	❌	RGB only
`PAL.Coder.SketchPalette`	XML	❌	❌	❌	❌	RGB only
`PAL.Coder.XMLPalette`	XML	✅	✅	✅	❌	✅

(A ColorType represents the type of color (global/spot/normal))

Simple Gradient support

The library additional defines PAL.Gradient which defines a collection of colors with positions that can be used when defining gradient types.

let gradient = PAL.Gradient(
   colorPositions: [
      (0.0, try PAL.Color(rgbHexString: "#FFFFFF")),
      (0.5, try PAL.Color(rgbHexString: "#444444")),
      (1.0, try PAL.Color(rgbHexString: "#000000"))
   ]
)

let coder = PAL.Gradient.Coder.JSON()

// Encode the gradient using the JSON encoder
let data = try coder.encode(gradient)

// Decode a gradient from data
let decoded = try PAL.Gradient.Decode(
   from: data,
   fileExtension: PAL.Gradient.Coder.JSON.fileExtension
)

The gradient coder includes basic importers/exporters.

Type	Description
`PAL.Gradient.Coder.JSON`	Built-in JSON format (.jsongradient)
`PAL.Gradient.Coder.GGR`	GIMP gradient file (.ggr)

.ggr support doesn’t respect segment blending functions other than linear (always imported as linear)
.ggr support doesn’t allow for segment coloring functions other than rgb (throws an error)

For some nice gradient files, cptcity has all of them :-)

cptcity also has a nice converter for gradients to ggr

Linux support

Linux only supports very naive color conversions between RGB-CMYK-Gray.

To build/test linux support using a mac

See: Testing Swift packages on Linux using Docker

Install Docker Desktop for Mac on your mac
Make sure that docker is running (or else the next command will fail with a weird or no error message)
Run the following command in the directory you want to mirror in your linux

docker run --rm --privileged --interactive --tty --volume "$(pwd):/src" --workdir "/src" swift:latest

Now, from within the docker container, run

swift build
swift test

Note that the /src directory in the Linux container is a direct mirror of the current directory on the host OS, not a copy. If you delete a file in /src in the Linux container, that file will be gone on the host OS, too.

Format specs

The .ase file format is not formally defined, however there are a number of deconstructions available on the web. I used the breakdown of the format defined here.

The .aco file format is defined here.

The .act file format is defined here.

The .acb format discussed and deined here

The CorelDraw/Adobe Illustrator .xml file format is (somewhat) defined here

License

MIT. Use it for anything you want, just attribute my work if you do. Let me know if you do use it somewhere, I’d love to hear about it!

MIT License

Copyright (c) 2023 Darren Ford

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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SOFTWARE.