Module outline

Expand description

Loading, scaling and hinting of glyph outlines.

This module provides support for retrieving (optionally scaled and hinted) glyph outlines in the form of vector paths.

§Drawing a glyph

Generating SVG path commands for a character (this assumes a local variable font of type FontRef):

use skrifa::{
    instance::{LocationRef, Size},
    outline::{DrawSettings, OutlinePen},
    FontRef, MetadataProvider,
};

// First, grab the set of outline glyphs from the font.
let outlines = font.outline_glyphs();

// Find the glyph identifier for our character.
let glyph_id = font.charmap().map('Q').unwrap();

// Grab the outline glyph.
let glyph = outlines.get(glyph_id).unwrap();

// Define how we want the glyph to be drawn. This creates
// settings for an instance without hinting at a size of
// 16px with no variations applied.
let settings = DrawSettings::unhinted(Size::new(16.0), LocationRef::default());

// Alternatively, we can apply variations like so:
let var_location = font.axes().location(&[("wght", 650.0), ("wdth", 100.0)]);
let settings = DrawSettings::unhinted(Size::new(16.0), &var_location);

// At this point, we need a "sink" to receive the resulting path. This
// is done by creating an implementation of the OutlinePen trait.

// Let's make one that generates SVG path data.
#[derive(Default)]
struct SvgPath(String);

// Implement the OutlinePen trait for this type. This emits the appropriate
// SVG path commands for each element type.
impl OutlinePen for SvgPath {
    fn move_to(&mut self, x: f32, y: f32) {
        self.0.push_str(&format!("M{x:.1},{y:.1} "));
    }

    fn line_to(&mut self, x: f32, y: f32) {
        self.0.push_str(&format!("L{x:.1},{y:.1} "));
    }

    fn quad_to(&mut self, cx0: f32, cy0: f32, x: f32, y: f32) {
        self.0
            .push_str(&format!("Q{cx0:.1},{cy0:.1} {x:.1},{y:.1} "));
    }

    fn curve_to(&mut self, cx0: f32, cy0: f32, cx1: f32, cy1: f32, x: f32, y: f32) {
        self.0.push_str(&format!(
            "C{cx0:.1},{cy0:.1} {cx1:.1},{cy1:.1} {x:.1},{y:.1} "
        ));
    }

    fn close(&mut self) {
        self.0.push_str("Z ");
    }
}
// Now, construct an instance of our pen.
let mut svg_path = SvgPath::default();

// And draw the glyph!
glyph.draw(settings, &mut svg_path).unwrap();

// See what we've drawn.
println!("{}", svg_path.0);

Modules§

autohint 🔒: Runtime autohinting support.
cff 🔒: Support for scaling CFF outlines.
error: Error types associated with outlines.
glyf 🔒: Scaling support for TrueType outlines.
hint 🔒: Support for applying embedded hinting instructions.
hint_reliant 🔒: Name detection for fonts that require hinting to be run for correct contours (FreeType calls these “tricky” fonts).
memory 🔒: Support for temporary memory allocation, making use of the stack for small sizes.
metrics 🔒: Helper for loading (possibly variable) horizontal glyph metrics.
path 🔒: TrueType style outline to path conversion.
pen: Types for collecting the output when drawing a glyph outline.
unscaled 🔒: Compact representation of an unscaled, unhinted outline.

Structs§

AdjustedMetrics: Information and adjusted metrics generated while drawing an outline glyph.
DrawSettings: Options that define how a glyph is drawn to a pen.
GlyphStyles: Set of derived glyph styles that are used for automatic hinting.
HintingInstance: Hinting instance that uses information embedded in the font to perform grid-fitting.
HintingOptions: Configuration settings for a hinting instance.
OutlineGlyph: A scalable glyph outline.
OutlineGlyphCollection: Collection of scalable glyph outlines.

Enums§

DrawError: Errors that may occur when drawing glyphs.
DrawInstance 🔒
Engine: Specifies the backend to use when applying hints.
Hinting: Specifies the hinting strategy for memory size calculations.
OutlineCollectionKind 🔒
OutlineGlyphFormat: Source format for an outline glyph.
OutlineKind 🔒
SmoothMode: Mode selector for a smooth hinting target.
Target: Defines the target settings for hinting.

Traits§

OutlinePen: Interface for accepting a sequence of path commands.

Functions§

with_glyf_memory 🔒: Invokes the callback with a memory buffer suitable for drawing the given TrueType outline.