1use crate::{
2 AssetSource, DevicePixels, IsZero, RenderImage, Result, SharedString, Size,
3 swap_rgba_pa_to_bgra,
4};
5use image::Frame;
6use resvg::tiny_skia::Pixmap;
7use smallvec::SmallVec;
8use std::{
9 hash::Hash,
10 sync::{Arc, LazyLock},
11};
12
13#[cfg(target_os = "macos")]
14const EMOJI_FONT_FAMILIES: &[&str] = &["Apple Color Emoji", ".AppleColorEmojiUI"];
15
16#[cfg(target_os = "windows")]
17const EMOJI_FONT_FAMILIES: &[&str] = &["Segoe UI Emoji", "Segoe UI Symbol"];
18
19#[cfg(any(target_os = "linux", target_os = "freebsd"))]
20const EMOJI_FONT_FAMILIES: &[&str] = &[
21 "Noto Color Emoji",
22 "Emoji One",
23 "Twitter Color Emoji",
24 "JoyPixels",
25];
26
27#[cfg(not(any(
28 target_os = "macos",
29 target_os = "windows",
30 target_os = "linux",
31 target_os = "freebsd",
32)))]
33const EMOJI_FONT_FAMILIES: &[&str] = &[];
34
35fn is_emoji_presentation(c: char) -> bool {
36 static EMOJI_PRESENTATION_REGEX: LazyLock<regex::Regex> =
37 LazyLock::new(|| regex::Regex::new("\\p{Emoji_Presentation}").unwrap());
38 let mut buf = [0u8; 4];
39 EMOJI_PRESENTATION_REGEX.is_match(c.encode_utf8(&mut buf))
40}
41
42fn font_has_char(db: &usvg::fontdb::Database, id: usvg::fontdb::ID, ch: char) -> bool {
43 db.with_face_data(id, |font_data, face_index| {
44 ttf_parser::Face::parse(font_data, face_index)
45 .ok()
46 .and_then(|face| face.glyph_index(ch))
47 .is_some()
48 })
49 .unwrap_or(false)
50}
51
52fn select_emoji_font(
53 ch: char,
54 fonts: &[usvg::fontdb::ID],
55 db: &usvg::fontdb::Database,
56 families: &[&str],
57) -> Option<usvg::fontdb::ID> {
58 for family_name in families {
59 let query = usvg::fontdb::Query {
60 families: &[usvg::fontdb::Family::Name(family_name)],
61 weight: usvg::fontdb::Weight(400),
62 stretch: usvg::fontdb::Stretch::Normal,
63 style: usvg::fontdb::Style::Normal,
64 };
65
66 let Some(id) = db.query(&query) else {
67 continue;
68 };
69
70 if fonts.contains(&id) || !font_has_char(db, id, ch) {
71 continue;
72 }
73
74 return Some(id);
75 }
76
77 None
78}
79
80/// When rendering SVGs, we render them at twice the size to get a higher-quality result.
81pub const SMOOTH_SVG_SCALE_FACTOR: f32 = 2.;
82
83#[derive(Clone, PartialEq, Hash, Eq)]
84#[expect(missing_docs)]
85pub struct RenderSvgParams {
86 pub path: SharedString,
87 pub size: Size<DevicePixels>,
88}
89
90#[derive(Clone)]
91/// A struct holding everything necessary to render SVGs.
92pub struct SvgRenderer {
93 asset_source: Arc<dyn AssetSource>,
94 usvg_options: Arc<usvg::Options<'static>>,
95}
96
97/// The size in which to render the SVG.
98pub enum SvgSize {
99 /// An absolute size in device pixels.
100 Size(Size<DevicePixels>),
101 /// A scaling factor to apply to the size provided by the SVG.
102 ScaleFactor(f32),
103}
104
105impl SvgRenderer {
106 /// Creates a new SVG renderer with the provided asset source.
107 pub fn new(asset_source: Arc<dyn AssetSource>) -> Self {
108 static SYSTEM_FONT_DB: LazyLock<Arc<usvg::fontdb::Database>> = LazyLock::new(|| {
109 let mut db = usvg::fontdb::Database::new();
110 db.load_system_fonts();
111 Arc::new(db)
112 });
113
114 let fontdb = {
115 let mut db = (**SYSTEM_FONT_DB).clone();
116 load_bundled_fonts(&*asset_source, &mut db);
117 fix_generic_font_families(&mut db);
118 Arc::new(db)
119 };
120
121 let default_font_resolver = usvg::FontResolver::default_font_selector();
122 let font_resolver = Box::new(
123 move |font: &usvg::Font, db: &mut Arc<usvg::fontdb::Database>| {
124 if db.is_empty() {
125 *db = fontdb.clone();
126 }
127 if let Some(id) = default_font_resolver(font, db) {
128 return Some(id);
129 }
130 // fontdb doesn't recognize CSS system font keywords like "system-ui"
131 // or "ui-sans-serif", so fall back to sans-serif before any face.
132 let sans_query = usvg::fontdb::Query {
133 families: &[usvg::fontdb::Family::SansSerif],
134 ..Default::default()
135 };
136 db.query(&sans_query)
137 .or_else(|| db.faces().next().map(|f| f.id))
138 },
139 );
140 let default_fallback_selection = usvg::FontResolver::default_fallback_selector();
141 let fallback_selection = Box::new(
142 move |ch: char, fonts: &[usvg::fontdb::ID], db: &mut Arc<usvg::fontdb::Database>| {
143 if is_emoji_presentation(ch) {
144 if let Some(id) = select_emoji_font(ch, fonts, db.as_ref(), EMOJI_FONT_FAMILIES)
145 {
146 return Some(id);
147 }
148 }
149
150 default_fallback_selection(ch, fonts, db)
151 },
152 );
153 let options = usvg::Options {
154 font_resolver: usvg::FontResolver {
155 select_font: font_resolver,
156 select_fallback: fallback_selection,
157 },
158 ..Default::default()
159 };
160 Self {
161 asset_source,
162 usvg_options: Arc::new(options),
163 }
164 }
165
166 /// Renders the given bytes into an image buffer.
167 pub fn render_single_frame(
168 &self,
169 bytes: &[u8],
170 scale_factor: f32,
171 ) -> Result<Arc<RenderImage>, usvg::Error> {
172 self.render_pixmap(
173 bytes,
174 SvgSize::ScaleFactor(scale_factor * SMOOTH_SVG_SCALE_FACTOR),
175 )
176 .map(|pixmap| {
177 let mut buffer =
178 image::ImageBuffer::from_raw(pixmap.width(), pixmap.height(), pixmap.take())
179 .unwrap();
180
181 for pixel in buffer.chunks_exact_mut(4) {
182 swap_rgba_pa_to_bgra(pixel);
183 }
184
185 let mut image = RenderImage::new(SmallVec::from_const([Frame::new(buffer)]));
186 image.scale_factor = SMOOTH_SVG_SCALE_FACTOR;
187 Arc::new(image)
188 })
189 }
190
191 pub(crate) fn render_alpha_mask(
192 &self,
193 params: &RenderSvgParams,
194 bytes: Option<&[u8]>,
195 ) -> Result<Option<(Size<DevicePixels>, Vec<u8>)>> {
196 anyhow::ensure!(!params.size.is_zero(), "can't render at a zero size");
197
198 let render_pixmap = |bytes| {
199 let pixmap = self.render_pixmap(bytes, SvgSize::Size(params.size))?;
200
201 // Convert the pixmap's pixels into an alpha mask.
202 let size = Size::new(
203 DevicePixels(pixmap.width() as i32),
204 DevicePixels(pixmap.height() as i32),
205 );
206 let alpha_mask = pixmap
207 .pixels()
208 .iter()
209 .map(|p| p.alpha())
210 .collect::<Vec<_>>();
211
212 Ok(Some((size, alpha_mask)))
213 };
214
215 if let Some(bytes) = bytes {
216 render_pixmap(bytes)
217 } else if let Some(bytes) = self.asset_source.load(¶ms.path)? {
218 render_pixmap(&bytes)
219 } else {
220 Ok(None)
221 }
222 }
223
224 fn render_pixmap(&self, bytes: &[u8], size: SvgSize) -> Result<Pixmap, usvg::Error> {
225 let tree = usvg::Tree::from_data(bytes, &self.usvg_options)?;
226 let svg_size = tree.size();
227 let scale = match size {
228 SvgSize::Size(size) => size.width.0 as f32 / svg_size.width(),
229 SvgSize::ScaleFactor(scale) => scale,
230 };
231
232 // Render the SVG to a pixmap with the specified width and height.
233 let mut pixmap = resvg::tiny_skia::Pixmap::new(
234 (svg_size.width() * scale) as u32,
235 (svg_size.height() * scale) as u32,
236 )
237 .ok_or(usvg::Error::InvalidSize)?;
238
239 let transform = resvg::tiny_skia::Transform::from_scale(scale, scale);
240
241 resvg::render(&tree, transform, &mut pixmap.as_mut());
242
243 Ok(pixmap)
244 }
245}
246
247fn load_bundled_fonts(asset_source: &dyn AssetSource, db: &mut usvg::fontdb::Database) {
248 let font_paths = [
249 "fonts/ibm-plex-sans/IBMPlexSans-Regular.ttf",
250 "fonts/lilex/Lilex-Regular.ttf",
251 ];
252 for path in font_paths {
253 match asset_source.load(path) {
254 Ok(Some(data)) => db.load_font_data(data.into_owned()),
255 Ok(None) => log::warn!("Bundled font not found: {path}"),
256 Err(error) => log::warn!("Failed to load bundled font {path}: {error}"),
257 }
258 }
259}
260
261// fontdb defaults generic families to Microsoft fonts ("Arial", "Times New Roman")
262// which aren't installed on most Linux systems. fontconfig normally overrides these,
263// but when it fails the defaults remain and all generic family queries return None.
264fn fix_generic_font_families(db: &mut usvg::fontdb::Database) {
265 use usvg::fontdb::{Family, Query};
266
267 let families_and_fallbacks: &[(Family<'_>, &str)] = &[
268 (Family::SansSerif, "IBM Plex Sans"),
269 // No serif font bundled; use sans-serif as best available fallback.
270 (Family::Serif, "IBM Plex Sans"),
271 (Family::Monospace, "Lilex"),
272 (Family::Cursive, "IBM Plex Sans"),
273 (Family::Fantasy, "IBM Plex Sans"),
274 ];
275
276 for (family, fallback_name) in families_and_fallbacks {
277 let query = Query {
278 families: &[*family],
279 ..Default::default()
280 };
281 if db.query(&query).is_none() {
282 match family {
283 Family::SansSerif => db.set_sans_serif_family(*fallback_name),
284 Family::Serif => db.set_serif_family(*fallback_name),
285 Family::Monospace => db.set_monospace_family(*fallback_name),
286 Family::Cursive => db.set_cursive_family(*fallback_name),
287 Family::Fantasy => db.set_fantasy_family(*fallback_name),
288 _ => {}
289 }
290 }
291 }
292}
293
294#[cfg(test)]
295mod tests {
296 use super::*;
297 use usvg::fontdb::{Database, Family, Query};
298
299 const IBM_PLEX_REGULAR: &[u8] =
300 include_bytes!("../../../assets/fonts/ibm-plex-sans/IBMPlexSans-Regular.ttf");
301 const LILEX_REGULAR: &[u8] = include_bytes!("../../../assets/fonts/lilex/Lilex-Regular.ttf");
302
303 fn db_with_bundled_fonts() -> Database {
304 let mut db = Database::new();
305 db.load_font_data(IBM_PLEX_REGULAR.to_vec());
306 db.load_font_data(LILEX_REGULAR.to_vec());
307 db
308 }
309
310 #[test]
311 fn test_is_emoji_presentation() {
312 let cases = [
313 ("a", false),
314 ("Z", false),
315 ("1", false),
316 ("#", false),
317 ("*", false),
318 ("ζΌ’", false),
319 ("δΈ", false),
320 ("γ«", false),
321 ("Β©", false),
322 ("β₯", false),
323 ("π", true),
324 ("β
", true),
325 ("πΊπΈ", true),
326 // SVG fallback is not cluster-aware yet
327 ("Β©οΈ", false),
328 ("β₯οΈ", false),
329 ("1οΈβ£", false),
330 ];
331 for (s, expected) in cases {
332 assert_eq!(
333 is_emoji_presentation(s.chars().next().unwrap()),
334 expected,
335 "for char {:?}",
336 s
337 );
338 }
339 }
340
341 #[test]
342 fn fix_generic_font_families_sets_all_families() {
343 let mut db = db_with_bundled_fonts();
344 fix_generic_font_families(&mut db);
345
346 let families = [
347 Family::SansSerif,
348 Family::Serif,
349 Family::Monospace,
350 Family::Cursive,
351 Family::Fantasy,
352 ];
353
354 for family in families {
355 let query = Query {
356 families: &[family],
357 ..Default::default()
358 };
359 assert!(
360 db.query(&query).is_some(),
361 "Expected generic family {family:?} to resolve after fix_generic_font_families"
362 );
363 }
364 }
365
366 #[test]
367 fn test_select_emoji_font_skips_family_without_glyph() {
368 let mut db = db_with_bundled_fonts();
369
370 let ibm_plex_sans = db
371 .query(&usvg::fontdb::Query {
372 families: &[usvg::fontdb::Family::Name("IBM Plex Sans")],
373 weight: usvg::fontdb::Weight(400),
374 stretch: usvg::fontdb::Stretch::Normal,
375 style: usvg::fontdb::Style::Normal,
376 })
377 .unwrap();
378 let lilex = db
379 .query(&usvg::fontdb::Query {
380 families: &[usvg::fontdb::Family::Name("Lilex")],
381 weight: usvg::fontdb::Weight(400),
382 stretch: usvg::fontdb::Stretch::Normal,
383 style: usvg::fontdb::Style::Normal,
384 })
385 .unwrap();
386 let selected = select_emoji_font('β', &[], &db, &["IBM Plex Sans", "Lilex"]).unwrap();
387
388 assert_eq!(selected, lilex);
389 assert!(!font_has_char(&db, ibm_plex_sans, 'β'));
390 assert!(font_has_char(&db, selected, 'β'));
391 }
392
393 #[test]
394 fn fix_generic_font_families_monospace_resolves_to_lilex() {
395 let mut db = db_with_bundled_fonts();
396 fix_generic_font_families(&mut db);
397
398 let query = Query {
399 families: &[Family::Monospace],
400 ..Default::default()
401 };
402 let id = db.query(&query).expect("Monospace should resolve");
403 let face = db.face(id).expect("Face should exist");
404 assert!(
405 face.families.iter().any(|(name, _)| name.contains("Lilex")),
406 "Monospace should map to Lilex, got {:?}",
407 face.families
408 );
409 }
410}