Chameleon

Chameleon is a utility that converts colors from one model to another. It currently supports: Hex, RGB, CMYK, HSL, HSV, Pantone, and Keywords.

Use

Chameleon represents colors using Elixir structs. Create a color using one of the provided structs:

iex> Chameleon.RGB.new(255, 0, 0)
%Chameleon.RGB{b: 0, g: 0, r: 255}

Once you have a color, Chameleon can convert that color to another colorspace or format:

iex> Chameleon.RGB.new(255, 0, 0) |> Chameleon.convert(Chameleon.HSV)
%Chameleon.HSV{h: 0, s: 100, v: 100}

iex> Chameleon.RGB.new(255, 0, 0) |> Chameleon.convert(Chameleon.Hex)
%Chameleon.Hex{hex: "FF0000"}

Chameleon can also convert strings:

iex> Chameleon.convert("#ff0000", Chameleon.RGB)
%Chameleon.RGB{b: 0, g: 0, r: 255}

iex> Chameleon.convert("red", Chameleon.CMYK)
%Chameleon.CMYK{c: 0, k: 0, m: 100, y: 100}

If Chameleon doesn't know how to convert the color, you'll get an error:

iex> Chameleon.convert("#112233", Chameleon.Pantone)
{:error, "No pantone match could be found for that color value."}

Adding color types

Chameleon uses Elixir protocols internally to perform the conversions. This makes it possible to add support for new colorspaces and formats in your own code. To do this, first create a struct for your color:

defmodule MyApp.FancyColor do
  @enforce_keys [:c1, :c2, :c3]
  defstruct @enforce_keys

  def new(c1, c2, c3), do: %__MODULE__{c1: c1, c2: c2, c3: c3}
end

Next, implement the color protocol. Your color can implement as many or as few color space protocols as you need. For example:

defimpl Chameleon.Color.RGB do
  def from(your_color_struct), do: MyApp.FancyColor.to_rgb(your_color_struct)
end

When Chameleon doesn't find a direct conversion from one color to another, it will attempt to convert through RGB. By supporting RGB conversions, your color type will be convertible between many color types. Of course, color conversion is frequently a lossy operation and you may want to implement more conversion modules.

Caveat(s)

Pantone is designed to be used on printed work only. As such, it is disingenuous to say a pantone value can be translated to a hex value since hex values will look different depending on the device displaying them. However, if you have a pantone value and want to find a device-displayable analog, this library will work.

Installation

The package can be installed by adding chameleon to your list of dependencies in mix.exs:

def deps do
  [
    {:chameleon, "~> 2.2.0"}
  ]
end

Contribution

Contributions are welcomed. Please open a pull request or file an issue with your ideas. Some ideas would be:

• Add a new color model for conversion
• Add functionality to generate complementary colors
• Handle errors for invalid input values

Copyright and License

Copyright (c) 2017 Todd Resudek

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.