｢‍｣ Lingenic Compose Engraving

Parser and renderer for .engraving copperplate/intaglio font files.

Overview

This crate provides tools for defining fonts in the engraving tradition: copperplate, steel engraving, drypoint, and other intaglio printmaking techniques where a burin is pushed through metal to create incised lines.

Engraving vs Lapidary

• Engraving: Burin pushed through ductile metal (copper, steel, zinc)
• Lapidary: Chisel struck into brittle stone (marble, granite)

Both are subtractive mark-making, but the techniques and tools differ. This crate focuses on the pushed technique with pressure-varying strokes.

Format

The .engraving format uses a verbose, self-documenting syntax:

.font-begin Copperplate
  units-per-em 1000
  ascender 800
  descender -200

  .plate-begin copper
    material Copper
    hardness 35
  .plate-end

  .burin-begin fine
    profile Lozenge
    angle 45
    face-width 20
  .burin-end

  .glyph-begin A U+0041
    advance-width 600
    engrave fine 50,0◊20 ⏤ 300,720◊80 ⏤ 550,0◊20
  .glyph-end

.font-end

Symbols

Pressure Modifier

Symbol	Unicode	Name	Description
◊	U+25CA	LOZENGE	Pressure at point (0-100, affects line width)

Example: 300,720◊80 = point at (300,720) with pressure 80

Path Connectors

Symbol	Unicode	Name	Description
⏤	U+23E4	STRAIGHTNESS	Straight line segment
⌒	U+2312	ARC	Smooth curve
∠	U+2220	ANGLE	Corner/sharp turn
↻	U+21BB	CLOCKWISE	Close path
⤴	U+2934	ARROW CURVING UPWARDS	Flick exit (lift-off)

Burin Profiles

Profile	Description	Use
Lozenge	Diamond-shaped with angle	Standard copperplate
Square	Square cross-section	Bold lines
Round	Circular cross-section	Stippling
Flat	Wide flat edge	Broad strokes
Spitsticker	Sharp fine point	Detail work
Onglette	Angled flat	Calligraphic effects

Plate Materials

Material	Hardness	Use
Copper	35	Traditional copperplate
Steel	65	Fine detail, longer runs
Zinc	25	Softer, easier cutting
Silver	28	Precious metalwork
Gold	24	Precious metalwork

Pressure and Line Width

Pressure values (0-100) control the line width:

• 0-20: Hairlines, delicate strokes
• 30-50: Medium weight
• 60-80: Bold strokes
• 80-100: Maximum width

The line width varies continuously along the stroke based on pressure, creating the characteristic swelling/thinning of engraved lines.

Drypoint and Burr

The burr keyword after a stroke enables burr rendering:

engrave fine 0,0◊30 ⏤ 200,0◊80 burr

In drypoint engraving, the burin throws up a ridge of metal (burr) that holds extra ink, creating rich, velvety lines. This effect can be simulated in rendering.

Flick Exits

The ⤙ symbol creates a flick exit where the burin lifts smoothly:

engrave fine 0,0◊60 ⏤ 200,0◊60 ⤴

This creates the tapered end characteristic of calligraphic strokes.

Example

use lingenic_compose_engraving::{parse, render::RenderOptions};
use lingenic_compose_engraving::render::render_glyph_to_svg;

let source = r#"
.font-begin Script
  units-per-em 1000
  ascender 800
  descender -200

  .burin-begin main
    profile Lozenge
    angle 45
    face-width 25
  .burin-end

  .glyph-begin l U+006C
    advance-width 250
    engrave main 125,0◊30 ⏤ 125,720◊30
  .glyph-end

.font-end
"#;

let font = parse(source).unwrap();
let glyph = font.get_glyph(0x006C).unwrap();
let svg = render_glyph_to_svg(&font, glyph, &RenderOptions::default());

Rendering

The renderer creates SVG with variable-width strokes:

use lingenic_compose_engraving::render::{RenderOptions, render_glyph_to_svg};

// Classic copperplate look
let options = RenderOptions::copperplate();

// Drypoint with burr effect
let options = RenderOptions::drypoint();

// Custom ink color
let options = RenderOptions::copperplate()
    .with_ink_color(ColorRgb::rgb(60, 20, 10));

License

Apache-2.0

Part of ｢‍｣ Lingenic Compose

｢‍｣ Lingenic Compose Engraving is a component of the ｢‍｣ Lingenic Compose typesetting system.

https://compose.lingenic.com/