Struct druid::env::Key

pub struct Key<T> { /* private fields */ }

A typed Env key.

This lets you retrieve values of a given type. The parameter implements ValueType. For “expensive” types, this is a reference, so the type for a string is Key<&str>.

Examples

const IMPORTANT_LABEL_COLOR: Key<Color> = Key::new("org.linebender.example.important-label-color");

fn important_label() -> Label<()> {
    Label::new("Warning!").with_text_color(IMPORTANT_LABEL_COLOR)
}

fn main() {
    let main_window = WindowDesc::new(important_label());

    AppLauncher::with_window(main_window)
        .configure_env(|env, _state| {
            // The `Key` must be set before it is used.
            env.set(IMPORTANT_LABEL_COLOR, Color::rgb(1.0, 0.0, 0.0));
        });
}

Implementations

impl<T> Key<T>

pub const fn new(key: &'static str) -> Self

Create a new strongly typed Key with the given string value. The type of the key will be inferred.

Examples

use druid::Key;
use druid::piet::Color;

let float_key: Key<f64> = Key::new("org.linebender.example.a.very.good.float");
let color_key: Key<Color> = Key::new("org.linebender.example.a.very.nice.color");

impl Key<()>

pub const fn untyped(key: &'static str) -> Self

Create an untyped Key with the given string value.

WARNING: This is not for general usage - it’s only useful for inspecting the contents of an Env - this is expected to be used for debugging, loading, and manipulating themes.

pub const fn raw(&self) -> &'static str

Return this key’s raw string value.

This should only be needed for things like debugging or for building other tooling that needs to inspect keys.

Trait Implementations

impl<T: Clone> Clone for Key<T>

fn clone(&self) -> Key<T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Data> Data for Key<T>

fn same(&self, other: &Self) -> bool

Determine whether two values are the same.

impl<T: Debug> Debug for Key<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> From<Key<Color>> for BackgroundBrush<T>

fn from(src: Key<Color>) -> BackgroundBrush<T>

Converts to this type from the input type.

impl<T> From<Key<T>> for ArcStr

fn from(src: Key<T>) -> ArcStr

Converts to this type from the input type.

impl<T: ValueType> From<Key<T>> for KeyOrValue<T>

fn from(key: Key<T>) -> KeyOrValue<T>

Converts to this type from the input type.

impl<T: ValueType> KeyLike<T> for Key<T>

fn changed(&self, old: &Env, new: &Env) -> bool

Returns true if this item has changed between the old and new Env.

impl<T: PartialEq> PartialEq<Key<T>> for Key<T>

fn eq(&self, other: &Key<T>) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T: Eq> Eq for Key<T>

impl<T> StructuralEq for Key<T>

impl<T> StructuralPartialEq for Key<T>