Struct SystemStyleDependencies 

#[repr(C)]
pub struct SystemStyleDependencies {
    pub facets: u32,
}

The set of SystemStyleDependency facets one layout() call declared.

A bitmask rather than a list: the facets are few, the union is the only operation, and it has to be cheap enough to fold on every declaration inside a deep widget tree.

Fields

facets: u32

Bitmask over SystemStyleDependency::bit. 0 = nothing declared, which is NOT “depends on nothing” — see Self::dom_depends_on_change.

Implementations

impl SystemStyleDependencies

pub const fn empty() -> Self

Nothing declared.

pub const fn all() -> Self

Every facet — what an undeclared callback is treated as.

pub const fn is_empty(&self) -> bool

Nothing has been declared yet.

pub const fn insert(&mut self, dep: SystemStyleDependency)

Fold one facet in.

pub const fn union(&mut self, other: Self)

Fold another set in.

pub const fn contains(&self, dep: SystemStyleDependency) -> bool

Was dep declared? Everything implies every facet.

pub fn dom_depends_on_change( &self, old: &SystemStyle, new: &SystemStyle, ) -> bool

Would a system-style change from old to new alter what the callback that declared these dependencies returns — i.e. does the change need a full Update::RefreshDom, or only a restyle?

An EMPTY set answers true. “Declared nothing” is not “depends on nothing”: it is the state of every callback written before this API existed, and of every callback that reads the OS style through a widget it does not control. Skipping their rebuild would leave the previous palette baked into the DOM — a silent wrong-colours bug that only a theme switch reveals. Declaring is opt-in; conservatism is the default.

Trait Implementations

impl Clone for SystemStyleDependencies

fn clone(&self) -> SystemStyleDependencies

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for SystemStyleDependencies

impl Debug for SystemStyleDependencies

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

Formats the value using the given formatter.

impl Default for SystemStyleDependencies

fn default() -> SystemStyleDependencies

Returns the “default value” for a type.

impl Eq for SystemStyleDependencies

impl Hash for SystemStyleDependencies

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 PartialEq for SystemStyleDependencies

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for SystemStyleDependencies