Expresso.Presenter.Program (expresso v0.1.0)

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Makes the program of the presenter for one deck

compile/2 takes a definition from Expresso.Presenter.Definition and a deck. The result holds numbers where the definition holds symbols, so the interpreter calculates almost nothing. For example, ArrowDown in the overview becomes {:select_by, 3} for a deck of 7 slides, because such a deck has 3 columns.

compile/2 also puts the each commands of a mode in front of each binding, and it makes a map from each event to its commands. A key with two bindings in one mode raises an error, because the list of keys would show two functions for it. Expresso.Presenter.Verifier refuses such a definition when it compiles.

A mode with the option element gets its each commands in element, and each other mode gets nil. The interpreter puts these commands in front of the commands of an element under a click.

Summary

Types

mode()

The commands for each event in one mode

t()

The program of one deck

Functions

columns(slides)

Return the number of columns in the overview for a number of slides

commands_value(commands)

Return a list of commands as a value for JSON, such as [["goto", 7]]

compile(definition, deck)

Make the program of a deck from a definition

element(slide)

Return the commands that a page in the overview holds for a slide

json(program)

Return the program as JSON for the script element

json_commands(commands)

Return a list of commands as JSON, such as [["step",1]]

link(index)

Return the commands of a link to the step at an index, for Expresso.Goto

menu(index)

Return the commands that a row of the menu holds for the step at an index

Types

mode()

@type mode() :: %{
  name: atom(),
  when: keyword(),
  any: [Expresso.Presenter.Definition.command()] | nil,
  keys: %{required(String.t()) => [Expresso.Presenter.Definition.command()]},
  click: %{required(atom()) => [Expresso.Presenter.Definition.command()]},
  swipe: %{required(atom()) => [Expresso.Presenter.Definition.command()]},
  element: [Expresso.Presenter.Definition.command()] | nil,
  other: [Expresso.Presenter.Definition.command()] | nil
}

The commands for each event in one mode

t()

@type t() :: %Expresso.Presenter.Program{
  modes: [mode()],
  project: Expresso.Presenter.Projection.t(),
  reset: [Expresso.Presenter.Definition.field()],
  slides: tuple(),
  state: map(),
  steps: tuple(),
  sync: [Expresso.Presenter.Definition.field()]
}

The program of one deck

steps holds {slide, step} for each step. slides holds a map for each slide: the index of its step 1, its number of steps and its transition. Both are tuples, so the interpreter reads an entry by its index.

Functions

columns(slides)

@spec columns(non_neg_integer()) :: pos_integer()

Return the number of columns in the overview for a number of slides

The result is the square root of the slide count, rounded up to an integer. The number of rows is then not more than the number of columns.

iex> Expresso.Presenter.Program.columns(7)
3

iex> Expresso.Presenter.Program.columns(0)
1

commands_value(commands)

@spec commands_value([Expresso.Presenter.Definition.command()]) :: [list()]

Return a list of commands as a value for JSON, such as [["goto", 7]]

json_commands/1 encodes this value. A caller that puts the commands into a larger value, such as Expresso.Goto.json/1, uses this function.

iex> Expresso.Presenter.Program.commands_value([{:goto, 7}])
[["goto", 7]]

compile(definition, deck)

@spec compile(Expresso.Presenter.Definition.t(), Expresso.Deck.t()) :: t()

Make the program of a deck from a definition

The first value of the field progress comes from the deck: the deck option progress false hides the progress bar at the start. A deck from the imperative API with no such key in its metadata shows the bar.

element(slide)

@spec element(pos_integer()) :: [Expresso.Presenter.Definition.command()]

Return the commands that a page in the overview holds for a slide

A click on the page goes to step 1 of the slide, and it closes the overview.

json(program)

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

Return the program as JSON for the script element

The JSON object has five keys:

  • "state" - the first value of each field of the state.
  • "sync" - the fields that a message to the other window holds, after the slide and the step.
  • "reset" - the fields that take their first value again at each change of the step.
  • "modes" - the modes, in the order that the interpreter examines them. A mode holds its "name", its condition "when", its "any" commands or null, its "other" commands or null, and its "element" commands or null. "keys", "click" and "swipe" hold pairs of events and commands. Each pair holds each event that has the same commands.
  • "project" - the projections, as Expresso.Presenter.Projection.json/1 returns them.

A command is a JSON array, such as ["step", 1], as json_commands/1 shows. The steps and the slides are not in the program, because Expresso.Steps.json/1 writes them. Expresso.Json.for_script/1 writes the text, as for the list of the steps.

json_commands(commands)

@spec json_commands([Expresso.Presenter.Definition.command()]) :: String.t()

Return a list of commands as JSON, such as [["step",1]]

The first element of each array is the name of the command. A field, a view and a built-in function become strings.

iex> Expresso.Presenter.Program.json_commands([{:goto_slide, 2}, {:set, :overview, false}])
~s([["goto_slide",2],["set","overview",false]])

link(index)

@spec link(non_neg_integer()) :: [Expresso.Presenter.Definition.command()]

Return the commands of a link to the step at an index, for Expresso.Goto

iex> Expresso.Presenter.Program.link(7)
[{:goto, 7}]