Macaw.Component.Context (macaw_component v0.1.2)

The context a component renders in (spec/02 §2): its mode, instance, size, root font size, heading level, theme, the viewer's preferences, and the holder's now.

The host computes it: on a page the core, elsewhere the adopter. The component never knows which, and never reads a clock: now is the holder's.

iex> {:ok, ctx} = Macaw.Component.Context.new(mode: :live, instance: "cards-1", size: {640, 400}, now: ~U[2026-10-28 12:00:00Z])
iex> {Macaw.Component.Context.heading(ctx, 0), Macaw.Component.Context.heading(ctx, 1)}
{"h2", "h3"}
iex> Macaw.Component.Context.id(ctx, "item-3")
"cards-1-item-3"

Summary

Functions

fields()

The fields, in the order of spec/02 §2's table.

heading(context, depth)

The heading element depth levels below the component's top (0 for its top): "h<level + depth>", never past "h6".

id(context, local)

An element id unique to the instance, "<instance>-<local>", stable across renders. local is a non-empty string of letters, digits, - and _; anything else raises ArgumentError, a programming error in the component.

new(attrs)

A context from a keyword list or a map: {:ok, context} or every fault at once, each {[field], reason}, an unknown field :unknown_key and a missing required one :required. The theme defaults to Macaw.Layers.Theme.default().

Types

t()

@type t() :: %Macaw.Component.Context{
  heading_level: 1..6,
  instance: String.t(),
  measured: boolean(),
  mode: Macaw.Component.Mode.t(),
  now: DateTime.t(),
  preferences: %{zone: String.t(), units: atom(), shortcuts: map()},
  root_font_size: number(),
  size: {number(), number()},
  theme: Macaw.Layers.Theme.t()
}