The colors' JSON adapter (spec/04 §1.6, §5): the map form of a literal color and of a
color value, for a document type that holds colors to write and read through its
Macaw.Layers.Form callbacks. Each is a tag, a transform's operands in their own forms,
and a theme's pinned steps $steps:
| Value | Map form |
|---|---|
%Macaw.Layers.Color{}, 8-bit exact | {"$rgb": "#3b6fa8"}, eight digits when translucent |
%Macaw.Layers.Color{}, any other | {"$rgb": [r, g, b, a]}, its fields |
{:color, "red"} | {"$color": "red"} |
{:series, 3} | {"$series": 3} |
{:ramp, "status", 0.5} | {"$ramp": ["status", 0.5]} |
{:lighten, c, 0.3}, and so each transform | {"$lighten": [C, 0.3]} |
{:blend, [c, …]} | {"$blend": [C, …]} |
{:contrast, :under}, {:contrast, c} | {"$contrast": "under"}, {"$contrast": C} |
%{500 => c, 100 => …}, each step a literal | {"$steps": [[100, …], [500, C]]}, each C its $rgb |
$rgb reads back the canonical struct (Macaw.Layers.Color.literal?/1), so decoding the
payload encode_value/1 writes of a literal color gives that color again. Its payload is
# and six or eight hex digits, or four numbers in their ranges; any other is no color.
A struct that is not a literal color has no form. A name is read as its string, as every
name of a theme is (spec/04 §2.1), and written from either spelling; a ramp of a name
that is none of Macaw.Layers.Theme.ramp_names/0 is no color. A string is
never a color: an operand or a step is a color's own form, and a bare string in its place
is no color. No atom is made from a document.
A type implements Macaw.Layers.Form.encode_value/1 and
Macaw.Layers.Form.decode_value/2 by calling these, and lists tags/0 among its live
tags. A value or payload these do not read is :default, which the kernel refuses at its
path.
The tags of visualize's Visualize.Chart.Codec, with $rgb.
Summary
Functions
The value of one of tags/0, its payload already read: {:ok, value}, or :default for
a tag or payload this reader does not read.
iex> Macaw.Layers.Color.Form.decode_value("$rgb", "#3b6fa8")
{:ok, %Macaw.Layers.Color{r: 59.0, g: 111.0, b: 168.0, opacity: 1.0}}
iex> Macaw.Layers.Color.Form.decode_value("$rgb", "steelblue")
:defaultA color's map form, {:ok, form}, or :default for a term that is not a color here.
iex> Macaw.Layers.Color.Form.encode_value(Macaw.Layers.Color.parse("#3b6fa880"))
{:ok, %{"$rgb" => "#3b6fa880"}}
iex> Macaw.Layers.Color.Form.encode_value(Macaw.Layers.Color.rgb(59.5, 111, 168))
{:ok, %{"$rgb" => [59.5, 111.0, 168.0, 1.0]}}@spec tags() :: [String.t(), ...]
The colors' tags, for a type's tag table.