mirror of
https://github.com/storytold/vectorcraft.git
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Jürg Lehni
c28ad99678
Each glyph's SVG document is read by the SVG importer, which the engine registers with the text crate.
50 lines
2.1 KiB
Rust
50 lines
2.1 KiB
Rust
//! OpenType SVG glyphs: a font's `SVG ` table holds SVG documents whose element `glyph<gid>` draws
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//! the glyph, in font units (y down, the origin at the glyph's). Turning SVG into art is the SVG
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//! importer's job, a layer above this crate, so the app registers it as the reader
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//! ([`set_svg_glyph_reader`]); without one, SVG glyphs keep their outlines.
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use std::sync::{Arc, OnceLock};
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use skrifa::GlyphId;
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use skrifa::raw::TableProvider;
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use vectorcraft_doc::Node;
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use vectorcraft_doc::color::Color;
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/// Turns glyph `gid`'s SVG document (possibly gzipped) of a font of `upem` units per em into its
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/// art in font units (y down), in the text's colours `fill` and `stroke`, and says whether it used
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/// them; `None` when it can't.
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pub type SvgGlyphReader = fn(document: &[u8], gid: u32, upem: f64, fill: Color, stroke: Option<Color>) -> Option<(Node, bool)>;
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static READER: OnceLock<SvgGlyphReader> = OnceLock::new();
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/// Registers the reader of SVG glyphs. The first one registered stays.
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pub fn set_svg_glyph_reader(reader: SvgGlyphReader) {
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let _ = READER.set(reader);
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}
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/// Does `font` have SVG glyphs?
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pub(crate) fn has_svg_glyphs(font: &skrifa::FontRef<'_>) -> bool {
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font.svg().is_ok()
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}
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/// Glyph `gid`'s SVG document in `font`, if it has one.
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fn document<'a>(font: &skrifa::FontRef<'a>, gid: u32) -> Option<&'a [u8]> {
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font.svg().ok().and_then(|t| t.glyph_data(GlyphId::new(gid)))
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}
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/// Does glyph `gid` of `font` have an SVG document?
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pub(crate) fn has_document(font: &skrifa::FontRef<'_>, gid: u32) -> bool {
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document(font, gid).is_some()
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}
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/// Glyph `gid`'s art from its SVG document, read by the registered reader, and whether it uses
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/// the text's colours. `None` without a document, a reader, or art.
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pub(crate) fn svg_glyph(font: &skrifa::FontRef<'_>, gid: u32, upem: f64, fill: Color, stroke: Option<Color>) -> (Option<Arc<Node>>, bool) {
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let Some(document) = document(font, gid) else { return (None, false) };
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let Some(reader) = READER.get() else { return (None, false) };
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match reader(document, gid, upem, fill, stroke) {
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Some((art, coloured)) => (Some(Arc::new(art)), coloured),
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None => (None, false),
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}
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}
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