gpui/
svg_renderer.rs

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, OnceLock},
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/// A parsed SVG document that can be rasterized at any scale.
98///
99/// Produced by [`SvgRenderer::parse_svg`] and rasterized by
100/// [`SvgRenderer::render_parsed`]. Parsing resolves fonts and converts text
101/// to paths, so callers that need to rasterize the same SVG at multiple
102/// scales should retain this value to avoid re-paying the parse cost.
103pub struct ParsedSvg(usvg::Tree);
104
105/// The size in which to rasterize the SVG.
106#[derive(Clone, Copy)]
107pub enum SvgSize {
108    /// A width in device pixels. The SVG retains its aspect ratio.
109    Size(Size<DevicePixels>),
110    /// An exact width and height in device pixels.
111    ExactSize(Size<DevicePixels>),
112    /// A logical scaling factor to apply to the size provided by the SVG.
113    ScaleFactor(f32),
114}
115
116impl From<f32> for SvgSize {
117    fn from(scale_factor: f32) -> Self {
118        Self::ScaleFactor(scale_factor)
119    }
120}
121
122impl SvgRenderer {
123    /// Creates a new SVG renderer with the provided asset source.
124    pub fn new(asset_source: Arc<dyn AssetSource>) -> Self {
125        static SYSTEM_FONT_DB: LazyLock<Arc<usvg::fontdb::Database>> = LazyLock::new(|| {
126            let mut db = usvg::fontdb::Database::new();
127            db.load_system_fonts();
128            Arc::new(db)
129        });
130
131        // Build the enriched font DB lazily on first SVG render rather than
132        // eagerly at construction time. This avoids the expensive deep-clone
133        // of the system font database for code paths that never render SVGs
134        // (e.g. tests).
135        let enriched_fontdb: Arc<OnceLock<Arc<usvg::fontdb::Database>>> = Arc::new(OnceLock::new());
136
137        let default_font_resolver = usvg::FontResolver::default_font_selector();
138        let font_resolver = Box::new({
139            let asset_source = asset_source.clone();
140            move |font: &usvg::Font, db: &mut Arc<usvg::fontdb::Database>| {
141                if db.is_empty() {
142                    let fontdb = enriched_fontdb.get_or_init(|| {
143                        let mut db = (**SYSTEM_FONT_DB).clone();
144                        load_bundled_fonts(&*asset_source, &mut db);
145                        fix_generic_font_families(&mut db);
146                        Arc::new(db)
147                    });
148                    *db = fontdb.clone();
149                }
150                if let Some(id) = default_font_resolver(font, db) {
151                    return Some(id);
152                }
153                // fontdb doesn't recognize CSS system font keywords like "system-ui"
154                // or "ui-sans-serif", so fall back to sans-serif before any face.
155                let sans_query = usvg::fontdb::Query {
156                    families: &[usvg::fontdb::Family::SansSerif],
157                    ..Default::default()
158                };
159                db.query(&sans_query)
160                    .or_else(|| db.faces().next().map(|f| f.id))
161            }
162        });
163        let default_fallback_selection = usvg::FontResolver::default_fallback_selector();
164        let fallback_selection = Box::new(
165            move |ch: char, fonts: &[usvg::fontdb::ID], db: &mut Arc<usvg::fontdb::Database>| {
166                if is_emoji_presentation(ch) {
167                    if let Some(id) = select_emoji_font(ch, fonts, db.as_ref(), EMOJI_FONT_FAMILIES)
168                    {
169                        return Some(id);
170                    }
171                }
172
173                default_fallback_selection(ch, fonts, db)
174            },
175        );
176        let options = usvg::Options {
177            font_resolver: usvg::FontResolver {
178                select_font: font_resolver,
179                select_fallback: fallback_selection,
180            },
181            ..Default::default()
182        };
183        Self {
184            asset_source,
185            usvg_options: Arc::new(options),
186        }
187    }
188
189    /// Parses SVG data into a [`ParsedSvg`] that can be rasterized at any scale.
190    #[ztracing::instrument(skip_all)]
191    pub fn parse_svg(&self, bytes: &[u8]) -> Result<ParsedSvg, usvg::Error> {
192        usvg::Tree::from_data(bytes, &self.usvg_options).map(ParsedSvg)
193    }
194
195    /// Rasterizes a previously parsed SVG into an image buffer.
196    #[ztracing::instrument(skip_all)]
197    pub fn render_parsed(
198        &self,
199        svg: &ParsedSvg,
200        size: impl Into<SvgSize>,
201    ) -> Result<Arc<RenderImage>, usvg::Error> {
202        let (size, image_scale_factor) = match size.into() {
203            SvgSize::Size(size) => (SvgSize::Size(size), 1.0),
204            SvgSize::ExactSize(size) => (SvgSize::ExactSize(size), 1.0),
205            SvgSize::ScaleFactor(scale_factor) => (
206                SvgSize::ScaleFactor(scale_factor * SMOOTH_SVG_SCALE_FACTOR),
207                SMOOTH_SVG_SCALE_FACTOR,
208            ),
209        };
210        let pixmap = rasterize_tree(&svg.0, size)?;
211        let mut buffer =
212            image::ImageBuffer::from_raw(pixmap.width(), pixmap.height(), pixmap.take()).unwrap();
213
214        for pixel in buffer.chunks_exact_mut(4) {
215            swap_rgba_pa_to_bgra(pixel);
216        }
217
218        let mut image = RenderImage::new(SmallVec::from_const([Frame::new(buffer)]));
219        image.scale_factor = image_scale_factor;
220        Ok(Arc::new(image))
221    }
222
223    /// Renders the given bytes into an image buffer.
224    pub fn render_single_frame(
225        &self,
226        bytes: &[u8],
227        scale_factor: f32,
228    ) -> Result<Arc<RenderImage>, usvg::Error> {
229        let svg = self.parse_svg(bytes)?;
230        self.render_parsed(&svg, scale_factor)
231    }
232
233    pub(crate) fn render_alpha_mask(
234        &self,
235        params: &RenderSvgParams,
236        bytes: Option<&[u8]>,
237    ) -> Result<Option<(Size<DevicePixels>, Vec<u8>)>> {
238        anyhow::ensure!(!params.size.is_zero(), "can't render at a zero size");
239
240        let render_pixmap = |bytes| {
241            let pixmap = self.render_pixmap(bytes, SvgSize::Size(params.size))?;
242
243            // Convert the pixmap's pixels into an alpha mask.
244            let size = Size::new(
245                DevicePixels(pixmap.width() as i32),
246                DevicePixels(pixmap.height() as i32),
247            );
248            let alpha_mask = pixmap
249                .pixels()
250                .iter()
251                .map(|p| p.alpha())
252                .collect::<Vec<_>>();
253
254            Ok(Some((size, alpha_mask)))
255        };
256
257        if let Some(bytes) = bytes {
258            render_pixmap(bytes)
259        } else if let Some(bytes) = self.asset_source.load(&params.path)? {
260            render_pixmap(&bytes)
261        } else {
262            Ok(None)
263        }
264    }
265
266    fn render_pixmap(&self, bytes: &[u8], size: SvgSize) -> Result<Pixmap, usvg::Error> {
267        let tree = usvg::Tree::from_data(bytes, &self.usvg_options)?;
268        rasterize_tree(&tree, size)
269    }
270}
271
272fn rasterize_tree(tree: &usvg::Tree, size: SvgSize) -> Result<Pixmap, usvg::Error> {
273    // Cap the size of the rendered pixmap to avoid texture allocation panics
274    // Related issue: #56466
275    const MAX_SIZE: f32 = 8192.0;
276
277    let svg_size = tree.size();
278    let (mut width, mut height) = match size {
279        SvgSize::Size(size) => {
280            let scale = i32::from(size.width) as f32 / svg_size.width();
281            (svg_size.width() * scale, svg_size.height() * scale)
282        }
283        SvgSize::ExactSize(size) => (i32::from(size.width) as f32, i32::from(size.height) as f32),
284        SvgSize::ScaleFactor(scale) => (svg_size.width() * scale, svg_size.height() * scale),
285    };
286
287    if width > MAX_SIZE {
288        log::warn!("Attempted to render pixmap where width ({width}) > MAX_SIZE ({MAX_SIZE})");
289    }
290    if height > MAX_SIZE {
291        log::warn!("Attempted to render pixmap where height ({height}) > MAX_SIZE ({MAX_SIZE})");
292    }
293    let scale = (MAX_SIZE / width).min(MAX_SIZE / height).min(1.0);
294    width *= scale;
295    height *= scale;
296
297    // Render the SVG to a pixmap with the specified width and height.
298    let mut pixmap = resvg::tiny_skia::Pixmap::new(width as u32, height as u32)
299        .ok_or(usvg::Error::InvalidSize)?;
300
301    let transform = resvg::tiny_skia::Transform::from_scale(
302        width / svg_size.width(),
303        height / svg_size.height(),
304    );
305
306    resvg::render(tree, transform, &mut pixmap.as_mut());
307
308    Ok(pixmap)
309}
310
311fn load_bundled_fonts(asset_source: &dyn AssetSource, db: &mut usvg::fontdb::Database) {
312    let font_paths = [
313        "fonts/ibm-plex-sans/IBMPlexSans-Regular.ttf",
314        "fonts/lilex/Lilex-Regular.ttf",
315    ];
316    for path in font_paths {
317        match asset_source.load(path) {
318            Ok(Some(data)) => db.load_font_data(data.into_owned()),
319            Ok(None) => log::warn!("Bundled font not found: {path}"),
320            Err(error) => log::warn!("Failed to load bundled font {path}: {error}"),
321        }
322    }
323}
324
325// fontdb defaults generic families to Microsoft fonts ("Arial", "Times New Roman")
326// which aren't installed on most Linux systems. fontconfig normally overrides these,
327// but when it fails the defaults remain and all generic family queries return None.
328fn fix_generic_font_families(db: &mut usvg::fontdb::Database) {
329    use usvg::fontdb::{Family, Query};
330
331    let families_and_fallbacks: &[(Family<'_>, &str)] = &[
332        (Family::SansSerif, "IBM Plex Sans"),
333        // No serif font bundled; use sans-serif as best available fallback.
334        (Family::Serif, "IBM Plex Sans"),
335        (Family::Monospace, "Lilex"),
336        (Family::Cursive, "IBM Plex Sans"),
337        (Family::Fantasy, "IBM Plex Sans"),
338    ];
339
340    for (family, fallback_name) in families_and_fallbacks {
341        let query = Query {
342            families: &[*family],
343            ..Default::default()
344        };
345        if db.query(&query).is_none() {
346            match family {
347                Family::SansSerif => db.set_sans_serif_family(*fallback_name),
348                Family::Serif => db.set_serif_family(*fallback_name),
349                Family::Monospace => db.set_monospace_family(*fallback_name),
350                Family::Cursive => db.set_cursive_family(*fallback_name),
351                Family::Fantasy => db.set_fantasy_family(*fallback_name),
352                _ => {}
353            }
354        }
355    }
356}
357
358#[cfg(test)]
359mod tests {
360    use super::*;
361    use usvg::fontdb::{Database, Family, Query};
362
363    const IBM_PLEX_REGULAR: &[u8] =
364        include_bytes!("../../../assets/fonts/ibm-plex-sans/IBMPlexSans-Regular.ttf");
365    const LILEX_REGULAR: &[u8] = include_bytes!("../../../assets/fonts/lilex/Lilex-Regular.ttf");
366
367    #[test]
368    fn renders_parsed_svg_at_requested_size() -> Result<()> {
369        let renderer = SvgRenderer::new(Arc::new(()));
370        let svg = renderer.parse_svg(
371            br#"<svg xmlns="http://www.w3.org/2000/svg" width="24pt" height="12pt"></svg>"#,
372        )?;
373        let requested_size = Size::new(DevicePixels(24), DevicePixels(12));
374        let image = renderer.render_parsed(&svg, SvgSize::ExactSize(requested_size))?;
375
376        assert_eq!(image.size(0), requested_size);
377        Ok(())
378    }
379
380    #[test]
381    fn preserves_aspect_ratio_for_width_constrained_size() -> Result<()> {
382        let renderer = SvgRenderer::new(Arc::new(()));
383        let svg = renderer.parse_svg(
384            br#"<svg xmlns="http://www.w3.org/2000/svg" width="24pt" height="12pt"></svg>"#,
385        )?;
386        let image = renderer.render_parsed(
387            &svg,
388            SvgSize::Size(Size::new(DevicePixels(24), DevicePixels(24))),
389        )?;
390
391        assert_eq!(image.size(0), Size::new(DevicePixels(24), DevicePixels(12)));
392        Ok(())
393    }
394
395    fn db_with_bundled_fonts() -> Database {
396        let mut db = Database::new();
397        db.load_font_data(IBM_PLEX_REGULAR.to_vec());
398        db.load_font_data(LILEX_REGULAR.to_vec());
399        db
400    }
401
402    #[test]
403    fn text_with_split_glyph_clusters_in_mixed_fonts_does_not_panic() {
404        let mut db = Database::new();
405        db.load_font_data(IBM_PLEX_REGULAR.to_vec());
406        db.load_font_data(LILEX_REGULAR.to_vec());
407        let options = usvg::Options {
408            fontdb: std::sync::Arc::new(db),
409            ..Default::default()
410        };
411
412        // A base letter followed by a stack of combining marks. Under HarfBuzz's
413        // default cluster merging every mark glyph shares the base's byte index,
414        // which is the "glyph splitting" condition that triggered the panic. The
415        // chunk must use two different fonts so the buggy merge path runs.
416        let zalgo = "e\u{0301}\u{0302}\u{0303}\u{0304}\u{0306}\u{0307}\u{0308}\u{030a}";
417        let svg = format!(
418            r#"<svg viewBox="0 0 200 200" xmlns="http://www.w3.org/2000/svg"><text font-family="Lilex" font-size="32">{zalgo}<tspan font-family="IBM Plex Sans">{zalgo}</tspan></text></svg>"#
419        );
420
421        // Before the fix this aborts via panic with a message like
422        // "removal index (is 5) should be < len (is 5)".
423        usvg::Tree::from_data(svg.as_bytes(), &options)
424            .expect("SVG with mixed-font text should parse");
425    }
426
427    #[test]
428    fn test_is_emoji_presentation() {
429        let cases = [
430            ("a", false),
431            ("Z", false),
432            ("1", false),
433            ("#", false),
434            ("*", false),
435            ("漢", false),
436            ("中", false),
437            ("カ", false),
438            ("©", false),
439            ("♥", false),
440            ("😀", true),
441            ("✅", true),
442            ("🇺🇸", true),
443            // SVG fallback is not cluster-aware yet
444            ("©️", false),
445            ("♥️", false),
446            ("1️⃣", false),
447        ];
448        for (s, expected) in cases {
449            assert_eq!(
450                is_emoji_presentation(s.chars().next().unwrap()),
451                expected,
452                "for char {:?}",
453                s
454            );
455        }
456    }
457
458    #[test]
459    fn fix_generic_font_families_sets_all_families() {
460        let mut db = db_with_bundled_fonts();
461        fix_generic_font_families(&mut db);
462
463        let families = [
464            Family::SansSerif,
465            Family::Serif,
466            Family::Monospace,
467            Family::Cursive,
468            Family::Fantasy,
469        ];
470
471        for family in families {
472            let query = Query {
473                families: &[family],
474                ..Default::default()
475            };
476            assert!(
477                db.query(&query).is_some(),
478                "Expected generic family {family:?} to resolve after fix_generic_font_families"
479            );
480        }
481    }
482
483    #[test]
484    fn test_select_emoji_font_skips_family_without_glyph() {
485        let mut db = db_with_bundled_fonts();
486
487        let ibm_plex_sans = db
488            .query(&usvg::fontdb::Query {
489                families: &[usvg::fontdb::Family::Name("IBM Plex Sans")],
490                weight: usvg::fontdb::Weight(400),
491                stretch: usvg::fontdb::Stretch::Normal,
492                style: usvg::fontdb::Style::Normal,
493            })
494            .unwrap();
495        let lilex = db
496            .query(&usvg::fontdb::Query {
497                families: &[usvg::fontdb::Family::Name("Lilex")],
498                weight: usvg::fontdb::Weight(400),
499                stretch: usvg::fontdb::Stretch::Normal,
500                style: usvg::fontdb::Style::Normal,
501            })
502            .unwrap();
503        let selected = select_emoji_font('│', &[], &db, &["IBM Plex Sans", "Lilex"]).unwrap();
504
505        assert_eq!(selected, lilex);
506        assert!(!font_has_char(&db, ibm_plex_sans, '│'));
507        assert!(font_has_char(&db, selected, '│'));
508    }
509
510    #[test]
511    fn fix_generic_font_families_monospace_resolves_to_lilex() {
512        let mut db = db_with_bundled_fonts();
513        fix_generic_font_families(&mut db);
514
515        let query = Query {
516            families: &[Family::Monospace],
517            ..Default::default()
518        };
519        let id = db.query(&query).expect("Monospace should resolve");
520        let face = db.face(id).expect("Face should exist");
521        assert!(
522            face.families.iter().any(|(name, _)| name.contains("Lilex")),
523            "Monospace should map to Lilex, got {:?}",
524            face.families
525        );
526    }
527}
gpui/svg_renderer.rs

gpui/
svg_renderer.rs
