Struct directwrite::descriptions::FontFeature

#[repr(C)]
pub struct FontFeature {
    pub name_tag: FontFeatureTag,
    pub parameter: u32,
}

Specifies properties used to identify and execute typographic features in the current font face.

Remarks

The OpenType standard provides access to typographic features available in the font by means of a feature tag with the associated parameters. The OpenType feature tag is a 4-byte identifier of the registered name of a feature. For example, the 'kern' feature name tag is used to identify the 'Kerning' feature in OpenType font. Similarly, the OpenType feature tag for 'Standard Ligatures' and 'Fractions' is 'liga' and 'frac' respectively. Since a single run can be associated with more than one typographic features, the Text String API accepts typographic settings for a run as a list of features and are executed in the order they are specified.

The value of the tag member represents the OpenType name tag of the feature, while the param value represents additional parameter for the execution of the feature referred by the tag member. Both nameTag and parameter are stored as little endian, the same convention followed by GDI. Most features treat the Param value as a binary value that indicates whether to turn the execution of the feature on or off, with it being off by default in the majority of cases. Some features, however, treat this value as an integral value representing the integer index to the list of alternate results it may produce during the execution; for instance, the feature 'Stylistic Alternates' or 'salt' uses the parameter value as an index to the list of alternate substituting glyphs it could produce for a specified glyph.

Fields

name_tag: FontFeatureTag

The feature's OpenType name identifier.

parameter: u32

The execution parameter of the feature.

A non-zero value generally enables the feature execution, while the zero value disables it. A feature requiring a selector uses this value to indicate the selector index.

Trait Implementations

impl Clone for FontFeature

fn clone(&self) -> FontFeature

Returns a copy of the value.

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

Performs copy-assignment from source.

impl PartialEq<FontFeature> for FontFeature

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

This method tests for self and other values to be equal, and is used by ==.

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

This method tests for !=.

impl PartialOrd<FontFeature> for FontFeature

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

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

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

This method tests less than (for self and other) and is used by the < operator.

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

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

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

This method tests greater than (for self and other) and is used by the > operator.

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

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

impl Eq for FontFeature

impl Ord for FontFeature

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

This method returns an Ordering between self and other.

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

Compares and returns the maximum of two values.

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

Compares and returns the minimum of two values.

impl Copy for FontFeature

impl From<FontFeature> for DWRITE_FONT_FEATURE

fn from(feature: FontFeature) -> DWRITE_FONT_FEATURE

Performs the conversion.

impl From<DWRITE_FONT_FEATURE> for FontFeature

fn from(feature: DWRITE_FONT_FEATURE) -> FontFeature

Performs the conversion.

impl Hash for FontFeature

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, 

Feeds a slice of this type into the given [Hasher].

impl Debug for FontFeature

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

Formats the value using the given formatter.