An element that plays a video file in a slide
The video entity takes the path of a WebM or an MP4 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 video for a screen reader,
and the poster option gives the path of an image. Both are required. The
poster shows on paper, in the handout view, in the speaker view, in the
overview, in the menu and while the video loads.
The video element holds only data-video, the number of the element in
the deck, and the renderer writes each video one time, as a data URI, into
the element expresso-videos. Expresso.Media gives the reasons. The
presenter gives a video its source when it plays.
The video plays in the present view only, while its slide shows and the
element shows at the current step. Thus at gives the step where it
starts. A black screen, the menu and the overview pause it. A video starts
again from the start when its slide shows again. It has no sound, because a
browser starts a video with sound only after a click. With
controls true, the video shows the controls of the browser, and the
presenter can turn the sound on. docs/reference/video-element.md gives
the rules.
Summary
Functions
Validate the captions option: the path of a WebVTT file
Make the assigns of the render function from the struct
Write the videos of a deck as JSON, or return nil
Give each video of a deck its number
Make the HTML of a video
Make sure that the source of a video is the path of a WebM or an MP4 file
Return the data URI of each file of the videos of a deck, in the order of their numbers
Types
@type t() :: %Expresso.Element.Video{ __spark_metadata__: term(), aspect: term(), at: term(), captions: term(), class: term(), controls: term(), easing: term(), effect: term(), el: term(), index: term(), loop: term(), morph: term(), on: term(), poster: term(), signature: term(), speed: term(), src: term(), steps: term(), title: term(), width: term() }
The struct of a video element
Functions
Validate the captions option: the path of a WebVTT file
iex> Expresso.Element.Video.captions("talk.vtt")
{:ok, "talk.vtt"}
iex> Expresso.Element.Video.captions("talk.srt")
{:error, "the captions must be a WebVTT file with the extension .vtt, and not \"talk.srt\""}Make the assigns of the render function from the struct
The key overlay holds the attributes of the overlay contract, and the
style attribute of the width and aspect options. The key poster
holds the data URI of the poster, and the key captions the data URI of the
captions, or nil.
@spec json(Expresso.Deck.t()) :: String.t() | nil
Write the videos of a deck as JSON, or return nil
The value is a list with the data URI of each video, in the order of their
numbers. A deck with no video gets nil, and the document then holds no
element expresso-videos.
@spec number(Expresso.Deck.t()) :: Expresso.Deck.t()
Give each video of a deck its number
Expresso.Renderer calls this function before the render, and the render
function writes the number into data-video. Expresso.Media.number/2
gives the rules.
@spec render(map()) :: Phoenix.HTML.safe()
Make the HTML of a video
The element has the box of an embed: the poster, and the video element on
it. The video element has no source, and the presenter gives it one. It
has no sound, and it plays inline on a phone. A video with no controls gets
tabindex="-1", so the key Tab does not go into it.
Make sure that the source of a video is the path of a WebM or an MP4 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, as for an image.
iex> Expresso.Element.Video.source("demo/demo.webm")
{:ok, "demo/demo.webm"}
iex> {:error, _message} = Expresso.Element.Video.source("demo/demo.mov")@spec sources(Expresso.Deck.t()) :: [String.t()]
Return the data URI of each file of the videos of a deck, in the order of their numbers
It raises for a file that it cannot read. Expresso.Media.sources/4 gives
the rules.