# Styles

Styles allow the look of Displayables to be customized, by changing the value of style properties. For example, changing the `background` property to change the background of a window or button.

Style properties can be prefixed by identifiers specifying when the property is used. For example, a button's `hover_background` property is used when it is focused, while its `idle_background` property is used when it is not. (Setting the `background` property sets both the `idle_background` and `hover_background`, among others.)

While Ren'Py has over 100 style properties, only a few of them are used in this section.

## Using Styles and Style Inheritance

Each displayable has a style built into it. When the displayable is created, either directly or using the screen system, style properties can be supplied, which are used to update the look of the displayable. In the following example:

    image big hello world = Text("Hello, World", size=40)

the `size` property is supplied to a Text displayable, allowing us to change its text size. This will customize the look of the text displayable by displaying the text 40 pixels high (though this also depends on the font).

Similarly, when using Screen Language, each user interface statement takes relevant style properties:

    screen big_hello_world:
        text "Hello, World" size 40

Individual styles exist to gather properties so they can be applied to displayables together. For example, these two texts will appear the same:

    image big one = Text("Hello, World", size=40, color="#f00")
    image big two = Text("Hello, World", style="big_red")

    style big_red:
        size 40
        color "#f00"

Each style has a set of properties, and one parent. When a given style is applied to a given displayable, each style property (among those taken by the displayable) will be looked for among the style's properties. If it's not found, it is searched in the parent style, and then in the parent's parent, and so on.

Each displayable takes a property named `style`, which applies the said style to the displayable:

    image big hello world = Text("Hello World", style="big")

    screen hello_world:
        text "Hello, World" style "big"

When no `style` property is given, a parent is chosen based on the kind of displayable that has been supplied. For example, buttons (including imagebuttons and textbuttons) default to the "button" style, grids to the "grid" style, and so on. The parent choice can be influenced by the style_prefix property of user interface statements in the screen language.

When a style is defined without a parent being specified, a default parent is chosen for the style. If the style contains an underscore (_) in its name, the parent is named by removing everything up to and including the first underscore. When a style that does not exist is used, and the style has an underscore in its name, Ren'Py will create it using the default parent. For example, a style named `my_button` will inherit from `button`. This inheritance can be changed using the style statement or using methods of the `Style` class. Otherwise, the style named "default" is used.

Style names beginning with an underscore are reserved for Ren'Py use.

As Ren'Py builds styles on startup, named styles should not be changed after the Init Phase.

During development, the Shift+I Style Inspecting can be very useful to check what styles and style properties are being used by a displayable.

## Defining Styles: Style Statement

The preferred way to define styles is through the style statement:

    style my_text is text:
        size 40
        font "gentium.ttf"

If a style does not exist, the style statement creates it. Otherwise, the existing style is modified by the style statement.

Note

Unlike other statements such as screen, transform or image, the style statement is not unique for a given name: several statements can refer to the same style and alter it successively, sometimes in a concurrent or contradictory way. In such cases, the init times at which the different style statements occur greatly matter over the final result.

A style statement begins with the keyword `style` and the name of the style to define. This is followed on the first line by zero or more clauses, and an optional colon.

If the colon is present, a block must follow. Each line of the block should contain one ore more clauses. Otherwise, the statement is complete.

The style statement accepts the following clauses:

style-property simple-expression

  Assigns the value of the simple expression to the given style property.

`is` parent

  Sets or replaces the parent of this style. The parent must be a word giving the name of a style.

`clear`

  Removes all properties of this style that were assigned before this style statement was run. This does not prevent the style from inheriting property values from its parents, and does not change its parent. To clear the parent of a style, use `is default` instead.

`take` style-name

  Clears all properties of this style that were assigned before this style statement was run, and replaces them with the properties of the named style. This does not change the parent of this style.

`variant` simple-expression

  Evaluates the simple expression, to yield a string or list of strings, which are interpreted as screen variants. If at least one of the variants given is active, the style statement is run, otherwise the rest of the block is ignored.

`properties` simple-expression

  Evaluates the simple expression to get a dictionary. The dictionary is expected to map style properties to values, and the values are assigned as if they were provided to the style statement.

Examples of style statements are:

    # Creates a new style, inheriting from default.
    style big_red:
        size 40

    # Updates the style.
    style big_red color "#f00"

    # Takes the properties of label_text from big_red, but only if we're
    # on a touch system.

    style label_text:
        variant "touch"
        take big_red

    # Style a has all the properties of style c, except that when not present
    # in c, the properties are taken from b or b's parents.
    style a is b:
        take c

Style statements are always run at init time.

## Defining Styles: Python

Named styles exists as fields on the global `style` object. To create a new style, create an instance of the `Style` class, and assign it to a field on the `style` object:

    init python:
        style.big_red = Style(style.default)

Style properties can be set by assigning to properties-like fields of the Style objects.

    init python:
        style.big_red.color = "#f00"
        style.big_red.size = 42

However, the value of a style property cannot be accessed this way, it can only be written.

class Style(parent)
  parent

    The styles parent. This can be another Style object, or a string.

  clear()

    This removes all style properties from this object. Values will be inherited from this object's parent.

    The equivalent of the `clear` clause in a style statement.

  set_parent(parent)

    Sets the parent of this style object to parent, which can be another Style object or a string.

    The equivalent of the `is` clause in a style statement.

  take(other)

    This takes all style properties from other, which can be another Style object or a string.

    The equivalent of the `take` clause in a style statement.

### Indexed Styles

Indexed styles are lightweight styles that can be used to customize the look of a displayable based on the data supplied to that displayable. An index style is created by indexing an existing Style object with a string or integer. If the indexed style does not exist, indexing creates it as a child of the original Style object.

    init python:
        style.button["Foo"].background = "#f00"
        style.button["Bar"].background = "#00f"

    screen indexed_style_test:
        vbox:
            textbutton "Foo" style style.button["Foo"]
            textbutton "Bar" style style.button["Bar"]

### Style Preferences

Note

GUI Preferences may often provide a better way of accomplishing the same thing, as a gui preference can change a variable used in multiple styles.

It's often desirable to allow the user to customize aspects of the user interface that are best expressed as styles. For example, a creator may want to give players the ability to adjust the look, color and size of the text. Style preferences allow for this customization.

A style preference is a preference controlling one or more style properties. A style preference has a name and one or more alternatives. At any given time, one of the available alternatives is selected, and saved in the persistent data. It defaults to the first registered alternative.

An alternative contains one or more associations of style, property, and value for that property. It represents a promise that when the alternative gets selected, that property on that style will be assigned that value. This occurs when Ren'Py first initializes, and then whenever a new alternative is selected.

One should ensure that every alternative for a given style preference updates the same set of styles and properties. Otherwise, the result will not be deterministic as going from one alternative to another and going back to the first one will leave some properties set as they are in the second alternative.

Here's an example of registering a style property that allows the user to choose between large, simple text, and smaller outlined text.

    init python:
        # The "decorated" alternative of the "text" preference will set the size to 22 on the "say_dialogue" style.
        renpy.register_style_preference("text", "decorated", style.say_dialogue, "size", 22)
        renpy.register_style_preference("text", "decorated", style.say_dialogue, "outlines", [ (1, "#000", 0, 0) ])

        renpy.register_style_preference("text", "large", style.say_dialogue, "size", 24)
        renpy.register_style_preference("text", "large", style.say_dialogue, "outlines", [ ])

        # The "decorated" alternative will be the default one for the "text" preference since it was registered first.

The following allows the user to select these alternatives using buttons:

    textbutton "Decorated" action StylePreference("text", "decorated")
    textbutton "Large" action StylePreference("text", "large")

StylePreference(preference, alternative)

  An action that causes alternative to become the selected alternative for the given style preference.

  The update event is triggered when this action is called.

  preference

    A string giving the name of the style preference.

  alternative

    A string giving the name of the alternative.

renpy.get_style_preference(preference)

  Returns a string giving the name of the selected alternative for the named style preference.

  preference

    A string giving the name of the style preference.

renpy.register_style_preference(preference, alternative, style, property, value)

  Registers information about an alternative for a style preference.

  preference

    A string, the name of the style preference.

  alternative

    A string, the name of the alternative.

  style

    The style that will be updated. This may be a style object or a string giving the style name.

  property

    A string giving the name of the style property that will be update.

  value

    The value that will be assigned to the style property.

renpy.set_style_preference(preference, alternative)

  Sets the selected alternative for the style preference.

  The update event is triggered when this function is called.

  preference

    A string giving the name of the style preference.

  alternative

    A string giving the name of the alternative.

### Other Style Functions

style.rebuild()

  This causes named styles to be rebuilt, allowing styles to be changed after the init phase has finished.

  Warning

  Named styles are not saved as part of the per-game data. This means that changes to them will not be persisted through a save and load cycle.