Expresso.Element.Audio (expresso v0.1.0)

An element that plays a sound file in a slide

The audio entity takes the path of an MP3, an M4A, an Ogg or a WAV file as its first argument, relative to the working directory of the command or to the root option of the deck. The title option names the sound for a screen reader, and the handout view and paper show it with a note symbol.

The audio element holds only data-audio, the number of the element in the deck, and the renderer writes each file one time, as a data URI, into the element expresso-audios. Expresso.Media gives the reasons.

The sound plays in the present view only, with the rules of a video: while its slide shows and the element shows at the current step. A black screen, the menu and the overview pause it, and it starts again from the start when its slide shows again. A browser plays sound only after the first key or click in the document, so a sound of the first slide starts at the first key. Without controls, the present view shows nothing in the place of the element. docs/reference/audio-element.md gives the rules.

Summary

Types

t()

The struct of an audio element

Functions

get_assigns(audio)

Make the assigns of the render function from the struct

json(deck)

Write the sounds of a deck as JSON, or return nil for a deck with none

number(deck)

Give each sound of a deck its number

render(assigns)

Make the HTML of a sound

source(value)

Make sure that the source of a sound is the path of an MP3, an M4A, an Ogg or a WAV file

sources(deck)

Return the data URI of each file of the sounds of a deck, in the order of their numbers

Types

t()

@type t() :: %Expresso.Element.Audio{
  __spark_metadata__: term(),
  at: term(),
  class: term(),
  controls: term(),
  easing: term(),
  effect: term(),
  el: term(),
  index: term(),
  loop: term(),
  morph: term(),
  on: term(),
  signature: term(),
  speed: term(),
  src: term(),
  steps: term(),
  title: term()
}

The struct of an audio element

Functions

get_assigns(audio)

@spec get_assigns(t()) :: map()

Make the assigns of the render function from the struct

json(deck)

@spec json(Expresso.Deck.t()) :: String.t() | nil

Write the sounds of a deck as JSON, or return nil for a deck with none

number(deck)

@spec number(Expresso.Deck.t()) :: Expresso.Deck.t()

Give each sound of a deck its number

Expresso.Renderer calls this function before the render, and the render function writes the number into data-audio.

render(assigns)

@spec render(map()) :: Phoenix.HTML.safe()

Make the HTML of a sound

The audio element has no source, and the presenter gives it one. An element with no controls gets tabindex="-1", so the key Tab does not go into it. The caption shows the title with a note symbol in the handout view and on paper, and the style sheet hides it in the present view.

source(value)

@spec source(term()) :: {:ok, String.t()} | {:error, String.t()}

Make sure that the source of a sound is the path of an MP3, an M4A, an Ogg or a WAV file

This function is the custom type of the first argument. It does not read the file, so a missing file gives an error at render time.

iex> Expresso.Element.Audio.source("sounds/bell.mp3")
{:ok, "sounds/bell.mp3"}

iex> {:error, _message} = Expresso.Element.Audio.source("sounds/bell.flac")

sources(deck)

@spec sources(Expresso.Deck.t()) :: [String.t()]

Return the data URI of each file of the sounds of a deck, in the order of their numbers