Struct RuntimeCapability 

pub struct RuntimeCapability {
    pub proportional_fonts: bool,
    pub subpixel_positioning: bool,
    pub hyphenation_available: bool,
    pub tracking_support: bool,
    pub ligature_support: bool,
    pub max_paragraph_words: usize,
}

Descriptor of available runtime capabilities.

The fallback logic inspects these flags to determine which features can be activated at a given tier.

Fields

proportional_fonts: bool

Whether proportional (variable-width) fonts are available. If false, all justification stretch/shrink is meaningless.

subpixel_positioning: bool

Whether sub-pixel positioning is available (e.g., WebGPU renderer). If false, baseline grid snapping and sub-cell glue are inert.

hyphenation_available: bool

Whether a hyphenation dictionary is loaded. If false, hyphenation break points are not generated.

tracking_support: bool

Whether inter-character spacing (tracking) is supported by the renderer.

ligature_support: bool

Whether ligature rendering is supported by the active runtime.

If false, shaping should deterministically fall back to canonical grapheme rendering for ligature-sensitive paths.

max_paragraph_words: usize

Maximum paragraph length (in words) that can be processed by the optimal breaker within the frame budget. 0 = unlimited.

Implementations

impl RuntimeCapability

pub const FULL: Self

Full capabilities: everything available.

pub const TERMINAL: Self

Terminal-only: monospace, no sub-pixel, no hyphenation.

pub const WEB: Self

Web renderer: proportional fonts but potentially limited tracking.

pub fn supports_tier(&self, tier: LayoutTier) -> bool

Check if the given tier’s features are supportable.

pub fn best_tier(&self) -> LayoutTier

Find the highest tier this capability set can support.

Trait Implementations

impl Clone for RuntimeCapability

fn clone(&self) -> RuntimeCapability

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for RuntimeCapability

impl Debug for RuntimeCapability

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

Formats the value using the given formatter.

impl Default for RuntimeCapability

fn default() -> RuntimeCapability

Returns the “default value” for a type.

impl Display for RuntimeCapability

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

Formats the value using the given formatter.

impl Eq for RuntimeCapability

impl Hash for RuntimeCapability

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 RuntimeCapability

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

Tests for self and other values to be equal, and is used by ==.

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

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

impl StructuralPartialEq for RuntimeCapability