# `Color.Behaviour`

Behaviour implemented by every color-space struct module in the
library.

Every space — `Color.SRGB`, `Color.Lab`, `Color.Oklch`,
`Color.JzAzBz`, `Color.YCbCr`, and so on — implements:

* `to_xyz/1`, which takes a struct of the implementing module and
  returns `{:ok, %Color.XYZ{}}`.

* `from_xyz/1`, which takes a `%Color.XYZ{}` and returns
  `{:ok, struct}` for the implementing module.

The hub module `Color` uses these two callbacks to perform any-to-any
conversion: every `convert/2,3,4` call goes `source → XYZ → target`.

A struct module that implements this behaviour is guaranteed to
round-trip losslessly through `Color.XYZ` up to floating-point
precision (ignoring irreversible gamut changes). Some modules
additionally accept options on `to_xyz/2` or `from_xyz/2` — the
behaviour's single-arity callbacks represent the common core.

# `color`

```elixir
@type color() :: struct()
```

The shape of any color-space struct returned by this library.

# `from_xyz`

```elixir
@callback from_xyz(Color.XYZ.t()) :: {:ok, color()} | {:error, Exception.t()}
```

Converts a `Color.XYZ` struct to the implementing module's struct
type.

# `to_xyz`

```elixir
@callback to_xyz(color()) :: {:ok, Color.XYZ.t()} | {:error, Exception.t()}
```

Converts a color of the implementing module's struct type to
`Color.XYZ`.

---

*Consult [api-reference.md](api-reference.md) for complete listing*