# `Cardbox.Hakushi`
[🔗](https://github.com/hattoriai/cardbox/blob/v0.1.0/lib/cardbox/hakushi.ex#L2)

A collection as a Hakushi canvas: each record a node, where people put
it, and the links of a relation of the collection to itself as edges.
A person who draws an edge links two records; who deletes one unlinks
them; who moves a node moves it in the view, for everyone who opens it.

    <Cardbox.Hakushi.canvas cardbox={MyApp.Cardbox} collection={@collection} view={@view}
      records={@records} actor={@user} class="h-[40rem]">
      <:record :let={record}>{record.data["title"]}</:record>
    </Cardbox.Hakushi.canvas>

The view is a saved `Cardbox.View` of type `canvas`: its `edges` option
names the relation whose links are the edges, and its `layout` keeps
where each record is (`%{"7" => %{"x" => 120, "y" => 40}}`). Records it
has no place for yet are laid out in layers, along their links, as the
canvas opens.

An edge goes from a record to the record whose relation links to it: on
a "Blocked by" relation, from the blocking record to the one it blocks.
A node is not deleted on the canvas: records are deleted where people
see all of them.

# `canvas`

A collection as a canvas of its records, joined by a relation's links.
## Attributes

* `cardbox` (`:atom`) (required) - your Cardbox module.
* `collection` (`Cardbox.Collection`) (required)
* `view` (`Cardbox.View`) (required)
* `records` (`:list`) (required) - the records to show (`list/3` of the view).
* `actor` (`:any`) - Defaults to `nil`.
* `id` (`:string`) - Defaults to `nil`.
* Global attributes are accepted. Supports all globals plus: `["class", "background", "grid", "snap", "minimap", "controls", "fit", "wheel", "readonly"]`.
## Slots

* `record` - a record's node, given the record as `:let`; its title by default.

# `change`

```elixir
@spec change(
  module(),
  Cardbox.Collection.t(),
  Cardbox.View.t(),
  Hakushi.Change.t(),
  map(),
  keyword()
) ::
  :ok | {:error, String.t()}
```

Saves a change of the canvas: places into the view's layout, edges
drawn and deleted as links of its relation. The `on_change` of a canvas
of your own (`Hakushi.Components.canvas/1`).

# `graph`

```elixir
@spec graph(Cardbox.Collection.t(), Cardbox.View.t(), [Cardbox.Record.t()]) ::
  Hakushi.Graph.t()
```

The graph of a canvas view: a node for each record, at its place in the
view (or in a column, for the layout to place), and an edge for each link
of the view's relation between two of them.

---

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