Struct FcFallbackConfig 

pub struct FcFallbackConfig {
    pub generic_families: BTreeMap<GenericFamily, Vec<String>>,
    pub substitutions: BTreeMap<String, Vec<String>>,
    pub script_fallbacks: Vec<FcScriptFallback>,
    pub last_resort: Vec<String>,
    pub default_generic: GenericFamily,
}

Fallback configuration for font resolution.

Fields

generic_families: BTreeMap<GenericFamily, Vec<String>>

Base candidates per generic family, best first.

substitutions: BTreeMap<String, Vec<String>>

Substitutions for named families that are not installed.

script_fallbacks: Vec<FcScriptFallback>

Per-script preferences, in priority order.

last_resort: Vec<String>

Last resort families used when no other font provides coverage.

default_generic: GenericFamily

Default generic family when a stack doesn’t specify one.

Implementations

impl FcFallbackConfig

pub fn empty() -> Self

Returns an empty fallback configuration.

pub fn os_defaults(os: OperatingSystem) -> Self

Returns the default OS-specific fallback configuration.

pub fn generic_candidates(&self, generic: GenericFamily) -> &[String]

Base candidates for generic, borrowing from its parent when it has no entry of its own.

pub fn substitutions_for(&self, family: &str) -> &[String]

Substitutions for the named family (normalized lookup).

pub fn script_candidates( &self, generic: Option<GenericFamily>, block: &UnicodeRange, ) -> Vec<String>

Returns the preferred fallback families for a given unicode range. Checks the specified generic family first (if any), followed by generic-agnostic fallbacks. Results are deduplicated and keep their order.

pub fn expand_generic( &self, generic: GenericFamily, ranges: &[UnicodeRange], ) -> Vec<String>

Every family name a generic may resolve to for text in ranges: script preferences for the overlapping blocks first, then the base candidates.

pub fn expand_family( &self, family: &str, ranges: &[UnicodeRange], ) -> Vec<String>

expand_generic for a generic keyword; a named family expands to itself followed by its substitutions.

pub fn candidate_families( &self, stack: &[String], ranges: &[UnicodeRange], ) -> Vec<String>

Expands a CSS font stack and unicode ranges into a complete, ordered list of candidate font families to search for.

pub fn merge_defaults(&mut self, defaults: &FcFallbackConfig)

Merges missing configuration values from defaults into this config. Does not overwrite or reorder existing entries.

pub fn extract_all_families(&self) -> Vec<String>

Take over parsed platform aliases (fonts.conf <alias><prefer>): a generic keyword becomes that generic’s base candidates, anything else a named-family substitution. Keys are normalized family names. Extract all unique font families listed in this fallback configuration.

pub fn absorb_system_aliases(&mut self, aliases: BTreeMap<String, Vec<String>>)

Trait Implementations

impl Clone for FcFallbackConfig

fn clone(&self) -> FcFallbackConfig

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for FcFallbackConfig

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

Formats the value using the given formatter.

impl Default for FcFallbackConfig

fn default() -> Self

Returns the “default value” for a type.

impl Eq for FcFallbackConfig

impl PartialEq for FcFallbackConfig

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for FcFallbackConfig