Struct Charmap

pub struct Charmap<'a> { /* private fields */ }

Mapping of characters to nominal glyph identifiers.

The mappings are derived from the cmap table. Depending on the font, the returned mapping may have entries that point to virtual/phantom glyph ids beyond the num_glyphs entry of the maxp table, which are only used during the shaping process, for example.

Obtaining a Charmap

Typically a Charmap is acquired by calling charmap on a FontRef.

Selection strategy

Fonts may contain multiple subtables in various formats supporting different encodings. The selection strategy implemented here is designed to choose mappings that capture the broadest available Unicode coverage:

• Unicode characters: a symbol mapping subtable is selected if available. Otherwise, subtables supporting the Unicode full repertoire or Basic Multilingual Plane (BMP) are preferred, in that order. Formats 4 and 12 are supported.

• Unicode variation sequences: these are provided by a format 14 subtable.

Implementations

impl<'a> Charmap<'a>

pub fn new(font: &FontRef<'a>) -> Charmap<'a>

Creates a new character map from the given font.

pub fn has_map(&self) -> bool

Returns true if a suitable Unicode character mapping is available.

pub fn is_symbol(&self) -> bool

Returns true if a symbol mapping was selected.

pub fn has_variant_map(&self) -> bool

Returns true if a Unicode variation sequence mapping is available.

pub fn map(&self, ch: impl Into<u32>) -> Option<GlyphId>

Maps a character to a nominal glyph identifier.

Returns None if a mapping does not exist.

pub fn mappings(&self) -> Mappings<'a>

Returns an iterator over all mappings of codepoint to nominal glyph identifiers in the character map.

pub fn map_variant( &self, ch: impl Into<u32>, selector: impl Into<u32>, ) -> Option<MapVariant>

Maps a character and variation selector to a nominal glyph identifier.

Returns None if a mapping does not exist.

pub fn variant_mappings(&self) -> VariantMappings<'a>

Returns an iterator over all mappings of character and variation selector to nominal glyph identifier in the character map.

Trait Implementations

impl<'a> Clone for Charmap<'a>

fn clone(&self) -> Charmap<'a>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<'a> Default for Charmap<'a>

fn default() -> Charmap<'a>

Returns the “default value” for a type.