Crate adobe_font_metrics

Expand description

Borrowing, zero-dependency Adobe Font Metrics (AFM) v4.x parser.

parse and parse_bytes retain global metadata, both writing directions, character advance vectors and ligatures, named/hexadecimal pair kerning, track kerning, and composite definitions. FontMetrics::advance resolves character advances against direction-specific CharWidth defaults.

Optional fields preserve absence. Comments and unrecognized records remain available through FontMetrics::source_records. Names and record text borrow the input; FontMetrics::into_owned detaches the entire model for storage. Numeric metrics use f32; source formatting is not preserved for serialization.

§Example

use adobe_font_metrics::{Direction, Vector, parse};
let source = "StartFontMetrics 4.1\nFontName Demo\nFontBBox 0 0 600 700\n\
              CharWidth 600 0\nStartCharMetrics 1\nC 65 ; N A ;\n\
              EndCharMetrics\nEndFontMetrics\n";
let font = parse(source)?;
assert_eq!(font.advance(&font.character_metrics[0], Direction::Zero),
           Some(Vector { x: 600.0, y: 0.0 }));
assert!(font.direction(Direction::Zero).fixed_pitch());

§Validation and limits

The reader checks modeled operands, finite numbers, section boundaries, declared section counts, and the closing font marker. Standalone pair/track sections are accepted for compatibility with existing callers. It does not resolve glyph references, interpret encodings, or certify all cross-field AFM constraints. Unknown records are preserved without interpretation.

AFM v3, ACFM/AMFM containers, multiple-master array interpretation, shaping, and serialization remain outside the implemented API. See the coverage audit and Adobe Tech Note 5004 for the precise boundary.

Modules§

error 🔒
model 🔒
parser 🔒
records 🔒

Structs§

BBox: A font or glyph bounding box, with ordinary f32 precision limits.
CharacterMetric: One character record; missing advances stay absent until resolved against the font.
Composite: A CC construction recipe; it does not synthesize outlines or character metrics.
CompositeComponent: One PCC component in a composite definition.
DirectionMetrics: Authored metrics for one writing direction. Shared blocks populate both entries.
FontMetrics: Parsed AFM metric data. Optional authored fields retain absence; accessors resolve defaults.
KerningPair: A complete pair adjustment in one writing direction.
Ligature: One L successor ligature rule. Every rule on a character is retained in order.
SourceRecord: Comment or uninterpreted extension data, ordered by appearance in the source.
TrackKern: One track-kerning curve, retained as its degree and endpoint values.
Vector: A point or displacement in AFM units (1/1000 of the font scale).

Enums§

CharacterCode: An encoded character number; hexadecimal digits are retained without angle brackets. These values are encoding-specific and are not Unicode scalar values.
Direction: AFM writing direction, independent of the sign or axis of an advance vector.
KerningOperands: Pair operands retain the distinction between glyph names and encoded hexadecimal values.
MetricsSets: MetricsSets or StartDirection selector; 2 applies to both directions.
ParseError: Errors returned by crate::parse. Line numbers are 1-based.
RecordContext: Location of a comment or unrecognized record within the parsed AFM structure.

Functions§

parse: Parse AFM v4.x text into borrowed font metrics.
parse_bytes: Parse AFM file bytes without a caller-side decoding step or lossy conversion. Names and text borrow the byte slice through a validated ASCII view.

Type Aliases§

OwnedFontMetrics: Fully owned AFM data that can outlive the original input.