Struct SemanticsProperties 

pub struct SemanticsProperties {
    pub role: Role,
    pub label: Option<String>,
    pub value: Option<String>,
    pub toggled: Toggled,
    pub clickable: bool,
    pub disabled: bool,
    pub range: Option<(f32, f32, f32)>,
}

A widget’s resolved semantic annotation, for accessibility.

Fields

role: Role

The announced role.

label: Option<String>

Accessible name (what the screen reader reads out).

value: Option<String>

Textual value (a field’s contents, a slider’s position, and so on).

toggled: Toggled

Checked state (checkboxes, switches, radios).

clickable: bool

Actionable by click — the screen reader offers “activate”.

disabled: bool

Disabled (greyed out, non-interactive).

range: Option<(f32, f32, f32)>

Numeric bounds (min, value, max) for sliders and progress bars.

Implementations

impl SemanticsProperties

pub fn new(role: Role) -> SemanticsProperties

An annotation carrying the given role and nothing else.

pub fn label(self, label: impl Into<String>) -> SemanticsProperties

Sets the accessible name.

pub fn value(self, value: impl Into<String>) -> SemanticsProperties

Sets the textual value.

pub fn toggled(self, on: bool) -> SemanticsProperties

Marks the checked state.

pub fn maybe_toggled(self, on: Option<bool>) -> SemanticsProperties

Marks it on, off, or partly on — None being the third answer, not a missing one.

pub fn clickable(self) -> SemanticsProperties

Marks the element as actionable.

pub fn disabled(self, disabled: bool) -> SemanticsProperties

Marks the element as disabled.

pub fn range(self, min: f32, value: f32, max: f32) -> SemanticsProperties

Sets the numeric bounds (min, value, max).

pub fn is_meaningful(&self) -> bool

true when this node carries something useful to assistive technology — a non-null role or a label. Empty containers are left out of the tree.

pub fn over(self, under: &SemanticsProperties) -> SemanticsProperties

This annotation laid over under, whose answers show through wherever this one said nothing.

What a container states about its child usually is not everything there is to say: something that marks a widget as a heading knows the role and has no idea what the words are. Dropping the child’s answer would replace a spoken title with silence, which is a worse outcome than the unlabelled heading it was fixing.

Two labels are joined, not chosen between — one line each, as the reference joins the labels of a merged subtree. A row holding a checkbox and its caption reads as one control with both, and picking one would drop the other on the floor with nothing to say which.

Every other field is this one’s answer, or the other’s where it had none, with each field’s “none” being its own: Role::None, Toggled::None, a false flag, an absent Option. clickable and disabled are unions rather than choices, because either one being true is a fact about the whole.

Trait Implementations

impl Clone for SemanticsProperties

fn clone(&self) -> SemanticsProperties

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for SemanticsProperties

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

Formats the value using the given formatter.

impl Default for SemanticsProperties

fn default() -> SemanticsProperties

Returns the “default value” for a type.

impl PartialEq for SemanticsProperties

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for SemanticsProperties