Struct Font

pub struct Font { /* private fields */ }

Available on crate feature dep_fontdue only.

Represents a font. Fonts are immutable after creation and owns its own copy of the font data.

Implementations

impl Font

pub fn from_bytes<Data>( data: Data, settings: FontSettings, ) -> Result<Font, &'static str>

where Data: Deref<Target = [u8]>,

Constructs a font from an array of bytes.

pub fn name(&self) -> Option<&str>

Returns the font’s face name if it has one. It is from Name ID 4 (Full Name) in the name table. See https://learn.microsoft.com/en-us/typography/opentype/spec/name#name-ids for more info.

pub fn chars(&self) -> &HashMap<char, NonZero<u16>>

Returns all valid unicode codepoints that have mappings to glyph geometry in the font, along with their associated index. This does not include grapheme cluster mappings. The mapped NonZeroU16 index can be used in the _indexed font functions.

pub fn file_hash(&self) -> usize

Returns a precomputed hash for the font file.

pub fn horizontal_line_metrics(&self, px: f32) -> Option<LineMetrics>

New line metrics for fonts that append characters to lines horizontally, and append new lines vertically (above or below the current line). Only populated for fonts with the appropriate metrics, none if it’s missing.

Arguments

• px - The size to scale the line metrics by. The units of the scale are pixels per Em unit.

pub fn vertical_line_metrics(&self, px: f32) -> Option<LineMetrics>

New line metrics for fonts that append characters to lines vertically, and append new lines horizontally (left or right of the current line). Only populated for fonts with the appropriate metrics, none if it’s missing.

Arguments

• px - The size to scale the line metrics by. The units of the scale are pixels per Em unit.

pub fn units_per_em(&self) -> f32

Gets the font’s units per em.

pub fn scale_factor(&self, px: f32) -> f32

Calculates the glyph’s outline scale factor for a given px size. The units of the scale are pixels per Em unit.

pub fn horizontal_kern(&self, left: char, right: char, px: f32) -> Option<f32>

Retrieves the horizontal scaled kerning value for two adjacent characters.

Arguments

• left - The character on the left hand side of the pairing.
• right - The character on the right hand side of the pairing.
• px - The size to scale the kerning value for. The units of the scale are pixels per Em unit.

Returns

• Option<f32> - The horizontal scaled kerning value if one is present in the font for the given left and right pair, None otherwise.

pub fn horizontal_kern_indexed( &self, left: u16, right: u16, px: f32, ) -> Option<f32>

Retrieves the horizontal scaled kerning value for two adjacent glyph indicies.

Arguments

• left - The glyph index on the left hand side of the pairing.
• right - The glyph index on the right hand side of the pairing.
• px - The size to scale the kerning value for. The units of the scale are pixels per Em unit.

Returns

• Option<f32> - The horizontal scaled kerning value if one is present in the font for the given left and right pair, None otherwise.

pub fn metrics(&self, character: char, px: f32) -> Metrics

Retrieves the layout metrics for the given character. If the character isn’t present in the font, then the layout for the font’s default character is returned instead.

Arguments

• index - The character in the font to to generate the layout metrics for.
• px - The size to generate the layout metrics for the character at. Cannot be negative. The units of the scale are pixels per Em unit.

Returns

• Metrics - Sizing and positioning metadata for the glyph.

pub fn metrics_indexed(&self, index: u16, px: f32) -> Metrics

Retrieves the layout metrics at the given index. You normally want to be using metrics(char, f32) instead, unless your glyphs are pre-indexed.

Arguments

• index - The glyph index in the font to to generate the layout metrics for.
• px - The size to generate the layout metrics for the glyph at. Cannot be negative. The units of the scale are pixels per Em unit.

Returns

• Metrics - Sizing and positioning metadata for the glyph.

pub fn rasterize_config(&self, config: GlyphRasterConfig) -> (Metrics, Vec<u8>)

Retrieves the layout rasterized bitmap for the given raster config. If the raster config’s character isn’t present in the font, then the layout and bitmap for the font’s default character’s raster is returned instead.

Arguments

• config - The settings to render the character at.

Returns

• Metrics - Sizing and positioning metadata for the rasterized glyph.
• Vec<u8> - Coverage vector for the glyph. Coverage is a linear scale where 0 represents 0% coverage of that pixel by the glyph and 255 represents 100% coverage. The vec starts at the top left corner of the glyph.

pub fn rasterize(&self, character: char, px: f32) -> (Metrics, Vec<u8>)

Retrieves the layout metrics and rasterized bitmap for the given character. If the character isn’t present in the font, then the layout and bitmap for the font’s default character is returned instead.

Arguments

• character - The character to rasterize.
• px - The size to render the character at. Cannot be negative. The units of the scale are pixels per Em unit.

Returns

• Metrics - Sizing and positioning metadata for the rasterized glyph.
• Vec<u8> - Coverage vector for the glyph. Coverage is a linear scale where 0 represents 0% coverage of that pixel by the glyph and 255 represents 100% coverage. The vec starts at the top left corner of the glyph.

pub fn rasterize_config_subpixel( &self, config: GlyphRasterConfig, ) -> (Metrics, Vec<u8>)

Retrieves the layout rasterized bitmap for the given raster config. If the raster config’s character isn’t present in the font, then the layout and bitmap for the font’s default character’s raster is returned instead.

This will perform the operation with the width multiplied by 3, as to simulate subpixels. Taking these as RGB values will perform subpixel anti aliasing.

Arguments

• config - The settings to render the character at.

Returns

• Metrics - Sizing and positioning metadata for the rasterized glyph.
• Vec<u8> - Swizzled RGB coverage vector for the glyph. Coverage is a linear scale where 0 represents 0% coverage of that subpixel by the glyph and 255 represents 100% coverage. The vec starts at the top left corner of the glyph.

pub fn rasterize_subpixel(&self, character: char, px: f32) -> (Metrics, Vec<u8>)

Retrieves the layout metrics and rasterized bitmap for the given character. If the character isn’t present in the font, then the layout and bitmap for the font’s default character is returned instead.

This will perform the operation with the width multiplied by 3, as to simulate subpixels. Taking these as RGB values will perform subpixel anti aliasing.

Arguments

• character - The character to rasterize.
• px - The size to render the character at. Cannot be negative. The units of the scale are pixels per Em unit.

Returns

• Metrics - Sizing and positioning metadata for the rasterized glyph.
• Vec<u8> - Swizzled RGB coverage vector for the glyph. Coverage is a linear scale where 0 represents 0% coverage of that subpixel by the glyph and 255 represents 100% coverage. The vec starts at the top left corner of the glyph.

pub fn rasterize_indexed(&self, index: u16, px: f32) -> (Metrics, Vec<u8>)

Retrieves the layout metrics and rasterized bitmap at the given index. You normally want to be using rasterize(char, f32) instead, unless your glyphs are pre-indexed.

Arguments

• index - The glyph index in the font to rasterize.
• px - The size to render the character at. Cannot be negative. The units of the scale are pixels per Em unit.

Returns

• Metrics - Sizing and positioning metadata for the rasterized glyph.
• Vec<u8> - Coverage vector for the glyph. Coverage is a linear scale where 0 represents 0% coverage of that pixel by the glyph and 255 represents 100% coverage. The vec starts at the top left corner of the glyph.

pub fn rasterize_indexed_subpixel( &self, index: u16, px: f32, ) -> (Metrics, Vec<u8>)

Retrieves the layout metrics and rasterized bitmap at the given index. You normally want to be using rasterize(char, f32) instead, unless your glyphs are pre-indexed.

This will perform the operation with the width multiplied by 3, as to simulate subpixels. Taking these as RGB values will perform subpixel anti aliasing.

Arguments

• index - The glyph index in the font to rasterize.
• px - The size to render the character at. Cannot be negative. The units of the scale are pixels per Em unit.

Returns

• Metrics - Sizing and positioning metadata for the rasterized glyph.
• Vec<u8> - Swizzled RGB coverage vector for the glyph. Coverage is a linear scale where 0 represents 0% coverage of that subpixel by the glyph and 255 represents 100% coverage. The vec starts at the top left corner of the glyph.

pub fn has_glyph(&self, character: char) -> bool

Checks if the font has a glyph for the given character.

pub fn lookup_glyph_index(&self, character: char) -> u16

Finds the internal glyph index for the given character. If the character is not present in the font then 0 is returned.

pub fn glyph_count(&self) -> u16

Gets the total glyphs in the font.

Trait Implementations

impl Clone for Font

fn clone(&self) -> Font

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Font

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

Formats the value using the given formatter.

impl Hash for Font

fn hash<H>(&self, state: &mut H)

where H: Hasher,

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.