Expresso.Theme (expresso v0.1.0)

The custom properties, the effects and the transitions of the theme

assets/style.css is the theme of this project, and the theme owns the custom properties. This module reads the file at compile time with Expresso.Css.scan/1, and it gives four answers. uses?/1 tells you whether the theme uses a property. declares?/1 tells you whether the theme gives the property a value. syntax/1 gives the syntax descriptor of the @property rule of the theme. effects/0 gives the effects of the theme, and transitions/0 gives its transitions between slides.

Expresso.Overlay.Properties reads the answers, and Expresso.Overlay.PropertyVerifier then gives a warning for a property that the theme does not use. The CSS of a deck adds its own names. docs/overlays.md gives the contract.

Summary

Functions

declares?(name)

Tell whether the theme gives the custom property of a name a value that is not a number

effects()

Give the effects of the theme, with the fade

names()

Give the names of the theme, for Expresso.Css.merge/2

syntax(name)

Give the syntax descriptor of the @property rule of the theme

transitions()

Give the transitions of the theme, with the fade and the kind none

uses?(name)

Tell whether the theme uses the custom property of a name

Functions

declares?(name)

@spec declares?(atom()) :: boolean()

Tell whether the theme gives the custom property of a name a value that is not a number

The compiler registers each state as a number with the initial value 0. That registration makes a value of a different type invalid, and the property then falls back to 0. A number stays valid. Therefore a state must not take the name of a property that the theme gives a value of a different type.

effects()

@spec effects() :: MapSet.t(String.t())

Give the effects of the theme, with the fade

names()

@spec names() :: Expresso.Css.names()

Give the names of the theme, for Expresso.Css.merge/2

The fade has no rule, because each element with steps fades. The function adds it to the effects. The browser fades from one slide to the next without a rule, and the kind none has no animation, so the function adds the two to the transitions.

syntax(name)

@spec syntax(atom()) :: String.t() | nil

Give the syntax descriptor of the @property rule of the theme

The function gives nil for a property that the theme does not register.

transitions()

@spec transitions() :: MapSet.t(String.t())

Give the transitions of the theme, with the fade and the kind none

uses?(name)

@spec uses?(atom()) :: boolean()

Tell whether the theme uses the custom property of a name

The name comes from the state option or from a key of the set option of an on entity.