Enum SystemStyleDependency 

#[repr(C)]
pub enum SystemStyleDependency {
    Theme = 0,
    Colors = 1,
    Fonts = 2,
    Metrics = 3,
    Icons = 4,
    Accessibility = 5,
    Everything = 6,
}

Which facet of the OS style a layout() callback read.

An “appearance change” is never one event. The light/dark polarity flips, or the accent colour moves, or the UI font grows, or the icon theme is swapped — and each of those reaches a different app differently. Whether the change can alter what layout() RETURNS depends entirely on what that callback read, and only the callback knows. LayoutCallbackInfo::depends_on_system_style is how it says so; this enum is the vocabulary.

Deliberately coarse. The distinction that pays is between the app that merely mirrors light/dark (its DOM is byte-identical across two different LIGHT schemes, so an accent change must not cost it a rebuild) and the app that baked colors.button_face into inline CSS inside layout() (its DOM is wrong the instant the palette moves). Finer facets would be more precise and nobody would declare them correctly.

Variants

Theme = 0

The light/dark polarity alone — LayoutCallbackInfo::get_theme.

Colors = 1

The colour palette: text, background, accent, button, selection.

Fonts = 2

The UI fonts — family, size, weight.

Metrics = 3

Sizing and spacing metrics: control sizes, scrollbar geometry, titlebar layout, input timings, focus ring.

Icons = 4

The icon theme and the icon styling options.

Accessibility = 5

Accessibility and motion preferences — reduced motion, high contrast, animation speed.

Everything = 6

Everything: the callback took the whole SystemStyle and the engine cannot see which parts of it were read. The conservative answer, and what LayoutCallbackInfo::get_system_style records.

Implementations

impl SystemStyleDependency

pub const fn bit(self) -> u32

This facet’s bit in a SystemStyleDependencies mask.

Trait Implementations

impl Clone for SystemStyleDependency

fn clone(&self) -> SystemStyleDependency

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for SystemStyleDependency

impl Debug for SystemStyleDependency

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

Formats the value using the given formatter.

impl Eq for SystemStyleDependency

impl Hash for SystemStyleDependency

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for SystemStyleDependency

fn cmp(&self, other: &SystemStyleDependency) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

fn clamp_to<R>(self, range: R) -> Self

where Self: Sized, R: ClampBounds<Self>,

🔬This is a nightly-only experimental API. (clamp_to)

Restrict a value to a certain range.

impl PartialEq for SystemStyleDependency

fn eq(&self, other: &SystemStyleDependency) -> bool

Equality operator ==.

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

Inequality operator !=.

impl PartialOrd for SystemStyleDependency

fn partial_cmp(&self, other: &SystemStyleDependency) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl StructuralPartialEq for SystemStyleDependency