A slide deck
The metadata of a deck can hold :progress. The value false hides the
progress bar of the present view at the start, and the key g can still
show it. A deck without the key shows the progress bar.
The metadata can also hold :print_notes. The value false leaves the
notes of the speaker out of the handout view and of the print. The speaker
view still shows them. A deck without the key prints the notes.
The metadata can also hold :slide_numbers. The value true shows the
number of each slide and the number of slides, such as 3 / 12, in a
corner of the slide. Slide 1 shows no number, because it is usually the
title slide. A deck without the key shows no number.
The metadata can also hold :duration, the length of the talk in minutes.
The speaker view then shows the time left and the pace. A deck without the
key, or with nil, shows neither.
The metadata can also hold :transition, the transition from one slide to
the next in the present view: :fade, :slide, :zoom, :none or a
transition of the CSS of the deck. The metadata of a slide can hold
:transition too, and it replaces the value of the deck for the move into
that slide. A deck without the key fades. The DSL makes sure that a
transition has a rule, and a struct of this module does not.
The metadata can also hold :morph, how the elements of two neighbor
slides move from one slide to the next: :auto, :named or :off. The
metadata of a slide can hold :morph too, and it replaces the value of the
deck for the move into that slide. A deck without the key uses :auto.
docs/reference/morph-option.md gives the rules.
The metadata can also hold :lang, the language of the text of the deck as
a language tag, such as "de". The renderer writes it into the lang
attribute of the html element. A deck without the key is English.
The metadata can also hold :dim_contrast, the minimum contrast ratio of
dimmed text, from 3 to 7. A deck without the key, or with nil, dims to
3:1. Expresso.Palette.with_dim_contrast/2 gives the rules.
The metadata can also hold :math_font, the font of each math element, one
of Expresso.Element.Math.Font.names/0. A deck without the key gets
:latin_modern. The renderer puts the font into a document with a math
element only.
The metadata can also hold :effect, the way in which an element with steps
shows and hides, such as :grow. The metadata of a slide and the effect
field of an element can hold it too, and the nearest value applies. A deck
without the key fades. Expresso.Overlay.Render.identify/1 gives the rules.
The metadata can also hold :speed and :easing, the time and the easing
of each animation in a slide. The speed is :fast, :normal, :slow or a
number of milliseconds, and the easing is :ease_in_out, :ease_out,
:linear or :spring. They follow the same rules as :effect. A deck
without the keys uses the time and the easing of the theme.
The metadata can also hold :css, a style sheet or the path of a file that
holds one. Expresso.Css.resolve/1 gives the rules. The renderer puts the
style sheet into the document after the theme.
Summary
Functions
Validate the minimum contrast ratio of dimmed text
Validate the language of a deck
Make the struct of a deck
Write the number of each slide into the metadata of the slide
Render a deck to HTML
Types
Functions
Validate the minimum contrast ratio of dimmed text
The value is a number from 3 to 7. 3 is the default of Expresso, 4.5 is the minimum of WCAG 2.2 for normal text, and 7 is its enhanced minimum.
iex> Expresso.Deck.dim_contrast(4.5)
{:ok, 4.5}
iex> Expresso.Deck.dim_contrast(2)
{:error, "the dim_contrast option must be a number from 3 to 7, such as 4.5, and not 2"}Validate the language of a deck
The value is a language tag of BCP 47 in its usual form: a language of two or three letters, then subtags of letters and digits, each after a hyphen.
iex> Expresso.Deck.lang("pt-BR")
{:ok, "pt-BR"}
iex> Expresso.Deck.lang("en_US")
{:error, "the lang option must be a language tag, such as \"en\" or \"pt-BR\", and not \"en_US\""}Make the struct of a deck
Expresso.from_dsl_state/1 calls this function. Make a deck with the DSL
or with Expresso.Builder.
Write the number of each slide into the metadata of the slide
The first slide is slide 1.
A slide from the DSL holds nil in its metadata field. This function puts an
empty map into that field first.
Render a deck to HTML
The HTML starts with the doctype of HTML 5. Floki drops a doctype node when it parses a document, so this function puts the doctype in front of the tree. Without the doctype a browser uses the quirks mode.
Each large data URI that the document holds more than one time stays in it
one time. Expresso.Assets gives the rules.
Floki writes the tree with no indentation. The pretty printer of Floki puts a line break between two elements, and it does not know an inline element. A line break becomes a space, and the text of a deck then gets a space in front of each inline element and after it.