Fonts

Default fonts

With the default default-fonts feature, Source Sans 3 regular and bold are compiled in and Document::render() uses them. No italic is bundled. lwpdf fonts lists the available default weights:

$ lwpdf fonts
sans-regular
sans-bold

The optional default-fonts-medium feature also bundles Source Sans 3 Medium under the sans-medium key, at the size cost listed in Cargo features.

Subsetting

Text is embedded as real Unicode via Type 0 / CIDFontType2 fonts. The subsetter in this repository embeds only the glyphs a document actually uses. A character the font has no glyph for is reported as a MissingGlyph layout warning rather than failing silently.

Your own fonts

FontRegistry is a dynamic registry keyed by FontKey, not fixed to two weights. Build one with your regular and bold TrueType files and render with it:

use lightweight_pdf::*;

let mut fonts = FontRegistry::with_fonts(REGULAR, BOLD)?;
fonts.register(FontKey::SANS_ITALIC, ITALIC)?;

let mut doc = Document::new(PageFormat::A4);
doc.add(Text::new("Set in a custom font."));
doc.add(Text::new("And in its italic.").italic());

let bytes = doc.render_with_fonts(&fonts)?;

• render_with_fonts() works without the default-fonts feature, so the bundled fonts stay out of your binary. examples/demo_custom_font.rs shows this and runs with --no-default-features.
• register() and register_named() add further weights under any key, for example FontKey::SANS_ITALIC and FontKey::SANS_BOLD_ITALIC.
• Any static TrueType font with glyf outlines works. Variable fonts and CFF/OTF fonts are rejected.

Missing font weights

Text::italic() and .bold_italic() render in italic once a font is registered under that key. Without such a registration, render() and render_with_diagnostics() return RenderError::MissingFont instead of silently substituting the default font.

In WASM and JavaScript

The WASM build can bundle the default fonts too, or register fonts at runtime with LightweightPdf.registerFont(key, bytes). See WASM and JavaScript for the trade-off in a Worker.

Licence

The bundled Source Sans 3 fonts are under the SIL Open Font License 1.1; the licence text is in assets/fonts/LICENSES/. The OFL permits embedding and subsetting in generated documents, so the PDFs you generate carry no OFL obligation.