@spec button(String.t()) :: t()

Creates a new button.

Examples

Create the widget:

button = Kino.Control.button("Hello")

Listen to events:

Kino.listen(button, fn event ->
  ...
end)

Or subscribe to them in a separate process:

Kino.Control.subscribe(button, :keyboard)

@spec form(
  [{atom(), Kino.Input.t()}],
  keyword()
) :: t()

Creates a new form.

A form is composed of regular inputs from the Kino.Input module, however in a form input values are not synchronized between users. Consequently, the form is another control for producing user-specific events.

Either :submit or :report_changes must be specified.

Options

• :submit - specifies the label to use for the submit button and enables submit events

• :report_changes - whether to send new form value whenever any of the input changes. Defaults to false

• :reset_on_submit - a list of fields to revert to their default values once the form is submitted. Use true to indicate all fields. Defaults to []

Event info

In addition to standard properties, all events include additional properties.

• :type - either :submit or :change

• :data - a map with field values, matching the field list

Examples

Create a form out of inputs:

form =
  Kino.Control.form(
    [
      name: Kino.Input.text("Name"),
      message: Kino.Input.textarea("Message")
    ],
    submit: "Send"
  )

Listen to events:

Kino.listen(form, fn event ->
  ...
end)

Or subscribe to them in a separate process:

Kino.Control.subscribe(form, :chat_form)

As users submit the form the payload is sent:

IEx.Helpers.flush()
#=> {:chat_form,
#=>   %{
#=>     data: %{message: "Hola", name: "Amy"},
#=>     origin: "client1",
#=>     type: :submit
#=>   }}
#=> {:chat_form,
#=>   %{
#=>     data: %{message: "Hey!", name: "Jake"},
#=>     origin: "client2",
#=>     type: :submit
#=>   }}

@spec interval(non_neg_integer()) :: interval()

Returns a new interval event source.

This can be used as event source for stream/1 and tagged_stream/1. The events are emitted periodically with an increasing value, starting from 0 and have the form:

%{type: :interval, iteration: non_neg_integer()}

@spec keyboard([:keyup | :keydown | :status], opts) :: t()
when opts: [{:default_handlers, :off | :on | :disable_only}]

Creates a new keyboard control.

This widget is represented as button that toggles interception mode, in which the given keyboard events are captured.

Keyboard shortcut

As of Livebook v0.11, keyboard controls can be toggled by focusing the cell and pressing ctrl + k (or ⌘ + k on MacOS).

Options

Note that these options require Livebook v0.11 or later.

• :default_handlers - controls Livebook's default keyboard shortcut handlers while the keyboard control is enabled. Must be one of:

  • :off (default) - all Livebook keyboard shortcuts are disabled

  • :on - all Livebook keyboard shortcuts are enabled

  • :disable_only - Livebook keyboard shortcuts are off except for the shortcut to toggle (disable) the control

Event info

In addition to standard properties, all events include additional properties.

Key events

• :type - either :keyup or :keydown

• :key - the value matching the browser KeyboardEvent.key

Status event

• :type - either :status

• :enabled - whether the keyboard is activated

Examples

Create the widget:

keyboard = Kino.Control.keyboard([:keyup, :keydown, :status])

Listen to events:

Kino.listen(keyboard, fn event ->
  ...
end)

Or subscribe to them in a separate process:

Kino.Control.subscribe(keyboard, :keyboard)

As the user types events are streamed:

IEx.Helpers.flush()
#=> {:keyboard, %{enabled: true, origin: "client1", type: :status}
#=> {:keyboard, %{key: "o", origin: "client1", type: :keydown}}
#=> {:keyboard, %{key: "k", origin: "client1", type: :keydown}}
#=> {:keyboard, %{key: "o", origin: "client1", type: :keyup}}
#=> {:keyboard, %{key: "k", origin: "client1", type: :keyup}}

@spec stream(event_source() | [event_source()]) :: Enumerable.t()

Merges several inputs and controls into a single stream of events.

It accepts a single source or a list of sources, where each source is either of:

• %Kino.Control{} - emitting value on relevant interaction

• %Kino.Input{} - emitting value on value change

• %Kino.JS.Live{} - emitting value programmatically

• interval/0 - emitting value periodically, see interval/1

You can then consume the stream to access its events. The stream is typically consumed via Kino.listen/2.

Example

button = Kino.Control.button("Hello")
input = Kino.Input.checkbox("Check")
interval = Kino.Control.interval(1000)

[button, input, interval]
|> Kino.Control.stream()
|> Kino.listen(fn event ->
  IO.inspect(event)
end)
#=> %{type: :interval, iteration: 0}
#=> %{origin: "client1", type: :click}
#=> %{origin: "client1", type: :change, value: true}

@spec subscribe(t() | Kino.Input.t(), term()) :: :ok

Subscribes the calling process to control or input events.

This is an alternative API to stream/1, such that event messages are consumed via process messages instead of streams.

The events are sent as {tag, info}, where info is a map with event details. In particular, it always includes :origin, which is an opaque identifier of the client that triggered the event.

@spec tagged_stream(keyword(event_source())) :: Enumerable.t()

Same as stream/1, but attaches custom tag to every stream item.

Example

button = Kino.Control.button("Hello")
input = Kino.Input.checkbox("Check")

[hello: button, check: input]
|> Kino.Control.tagged_stream()
|> Kino.listen(fn event ->
  IO.inspect(event)
end)
#=> {:hello, %{origin: "client1", type: :click}}
#=> {:check, %{origin: "client1", type: :change, value: true}}

@spec unsubscribe(t() | Kino.Input.t()) :: :ok

Unsubscribes the calling process from control or input events.