1mod font_features;
2mod line;
3mod line_layout;
4mod line_wrapper;
5
6pub use font_features::*;
7pub use line::*;
8pub use line_layout::*;
9pub use line_wrapper::*;
10
11use crate::{
12 px, Bounds, DevicePixels, EntityId, Hsla, Pixels, PlatformTextSystem, Point, Result,
13 SharedString, Size, UnderlineStyle,
14};
15use anyhow::anyhow;
16use collections::{FxHashMap, FxHashSet};
17use core::fmt;
18use itertools::Itertools;
19use parking_lot::{Mutex, RwLock, RwLockUpgradableReadGuard};
20use smallvec::{smallvec, SmallVec};
21use std::{
22 cmp,
23 fmt::{Debug, Display, Formatter},
24 hash::{Hash, Hasher},
25 ops::{Deref, DerefMut},
26 sync::Arc,
27};
28
29#[derive(Hash, PartialEq, Eq, Clone, Copy, Debug)]
30#[repr(C)]
31pub struct FontId(pub usize);
32
33#[derive(Hash, PartialEq, Eq, Clone, Copy, Debug)]
34pub struct FontFamilyId(pub usize);
35
36pub(crate) const SUBPIXEL_VARIANTS: u8 = 4;
37
38pub struct TextSystem {
39 line_layout_cache: Arc<LineLayoutCache>,
40 platform_text_system: Arc<dyn PlatformTextSystem>,
41 font_ids_by_font: RwLock<FxHashMap<Font, FontId>>,
42 font_metrics: RwLock<FxHashMap<FontId, FontMetrics>>,
43 raster_bounds: RwLock<FxHashMap<RenderGlyphParams, Bounds<DevicePixels>>>,
44 wrapper_pool: Mutex<FxHashMap<FontIdWithSize, Vec<LineWrapper>>>,
45 font_runs_pool: Mutex<Vec<Vec<FontRun>>>,
46 fallback_font_stack: SmallVec<[Font; 2]>,
47}
48
49impl TextSystem {
50 pub fn new(platform_text_system: Arc<dyn PlatformTextSystem>) -> Self {
51 TextSystem {
52 line_layout_cache: Arc::new(LineLayoutCache::new(platform_text_system.clone())),
53 platform_text_system,
54 font_metrics: RwLock::default(),
55 raster_bounds: RwLock::default(),
56 font_ids_by_font: RwLock::default(),
57 wrapper_pool: Mutex::default(),
58 font_runs_pool: Mutex::default(),
59 fallback_font_stack: smallvec![
60 // TODO: This is currently Zed-specific.
61 // We should allow GPUI users to provide their own fallback font stack.
62 font("Zed Mono"),
63 font("Helvetica")
64 ],
65 }
66 }
67
68 pub fn add_fonts(&self, fonts: &[Arc<Vec<u8>>]) -> Result<()> {
69 self.platform_text_system.add_fonts(fonts)
70 }
71
72 pub fn font_id(&self, font: &Font) -> Result<FontId> {
73 let font_id = self.font_ids_by_font.read().get(font).copied();
74 if let Some(font_id) = font_id {
75 Ok(font_id)
76 } else {
77 let font_id = self.platform_text_system.font_id(font)?;
78 self.font_ids_by_font.write().insert(font.clone(), font_id);
79 Ok(font_id)
80 }
81 }
82
83 /// Resolves the specified font, falling back to the default font stack if
84 /// the font fails to load.
85 ///
86 /// # Panics
87 ///
88 /// Panics if the font and none of the fallbacks can be resolved.
89 pub fn resolve_font(&self, font: &Font) -> FontId {
90 if let Ok(font_id) = self.font_id(font) {
91 return font_id;
92 }
93
94 for fallback in &self.fallback_font_stack {
95 if let Ok(font_id) = self.font_id(fallback) {
96 return font_id;
97 }
98 }
99
100 panic!(
101 "failed to resolve font '{}' or any of the fallbacks: {}",
102 font.family,
103 self.fallback_font_stack
104 .iter()
105 .map(|fallback| &fallback.family)
106 .join(", ")
107 );
108 }
109
110 pub fn bounding_box(&self, font_id: FontId, font_size: Pixels) -> Bounds<Pixels> {
111 self.read_metrics(font_id, |metrics| metrics.bounding_box(font_size))
112 }
113
114 pub fn typographic_bounds(
115 &self,
116 font_id: FontId,
117 font_size: Pixels,
118 character: char,
119 ) -> Result<Bounds<Pixels>> {
120 let glyph_id = self
121 .platform_text_system
122 .glyph_for_char(font_id, character)
123 .ok_or_else(|| anyhow!("glyph not found for character '{}'", character))?;
124 let bounds = self
125 .platform_text_system
126 .typographic_bounds(font_id, glyph_id)?;
127 Ok(self.read_metrics(font_id, |metrics| {
128 (bounds / metrics.units_per_em as f32 * font_size.0).map(px)
129 }))
130 }
131
132 pub fn advance(&self, font_id: FontId, font_size: Pixels, ch: char) -> Result<Size<Pixels>> {
133 let glyph_id = self
134 .platform_text_system
135 .glyph_for_char(font_id, ch)
136 .ok_or_else(|| anyhow!("glyph not found for character '{}'", ch))?;
137 let result = self.platform_text_system.advance(font_id, glyph_id)?
138 / self.units_per_em(font_id) as f32;
139
140 Ok(result * font_size)
141 }
142
143 pub fn units_per_em(&self, font_id: FontId) -> u32 {
144 self.read_metrics(font_id, |metrics| metrics.units_per_em)
145 }
146
147 pub fn cap_height(&self, font_id: FontId, font_size: Pixels) -> Pixels {
148 self.read_metrics(font_id, |metrics| metrics.cap_height(font_size))
149 }
150
151 pub fn x_height(&self, font_id: FontId, font_size: Pixels) -> Pixels {
152 self.read_metrics(font_id, |metrics| metrics.x_height(font_size))
153 }
154
155 pub fn ascent(&self, font_id: FontId, font_size: Pixels) -> Pixels {
156 self.read_metrics(font_id, |metrics| metrics.ascent(font_size))
157 }
158
159 pub fn descent(&self, font_id: FontId, font_size: Pixels) -> Pixels {
160 self.read_metrics(font_id, |metrics| metrics.descent(font_size))
161 }
162
163 pub fn baseline_offset(
164 &self,
165 font_id: FontId,
166 font_size: Pixels,
167 line_height: Pixels,
168 ) -> Pixels {
169 let ascent = self.ascent(font_id, font_size);
170 let descent = self.descent(font_id, font_size);
171 let padding_top = (line_height - ascent - descent) / 2.;
172 padding_top + ascent
173 }
174
175 fn read_metrics<T>(&self, font_id: FontId, read: impl FnOnce(&FontMetrics) -> T) -> T {
176 let lock = self.font_metrics.upgradable_read();
177
178 if let Some(metrics) = lock.get(&font_id) {
179 read(metrics)
180 } else {
181 let mut lock = RwLockUpgradableReadGuard::upgrade(lock);
182 let metrics = lock
183 .entry(font_id)
184 .or_insert_with(|| self.platform_text_system.font_metrics(font_id));
185 read(metrics)
186 }
187 }
188
189 pub fn with_view<R>(&self, view_id: EntityId, f: impl FnOnce() -> R) -> R {
190 self.line_layout_cache.with_view(view_id, f)
191 }
192
193 pub fn layout_line(
194 &self,
195 text: &str,
196 font_size: Pixels,
197 runs: &[TextRun],
198 ) -> Result<Arc<LineLayout>> {
199 let mut font_runs = self.font_runs_pool.lock().pop().unwrap_or_default();
200 for run in runs.iter() {
201 let font_id = self.resolve_font(&run.font);
202 if let Some(last_run) = font_runs.last_mut() {
203 if last_run.font_id == font_id {
204 last_run.len += run.len;
205 continue;
206 }
207 }
208 font_runs.push(FontRun {
209 len: run.len,
210 font_id,
211 });
212 }
213
214 let layout = self
215 .line_layout_cache
216 .layout_line(text, font_size, &font_runs);
217
218 font_runs.clear();
219 self.font_runs_pool.lock().push(font_runs);
220
221 Ok(layout)
222 }
223
224 pub fn shape_line(
225 &self,
226 text: SharedString,
227 font_size: Pixels,
228 runs: &[TextRun],
229 ) -> Result<ShapedLine> {
230 debug_assert!(
231 text.find('\n').is_none(),
232 "text argument should not contain newlines"
233 );
234
235 let mut decoration_runs = SmallVec::<[DecorationRun; 32]>::new();
236 for run in runs {
237 if let Some(last_run) = decoration_runs.last_mut() {
238 if last_run.color == run.color
239 && last_run.underline == run.underline
240 && last_run.background_color == run.background_color
241 {
242 last_run.len += run.len as u32;
243 continue;
244 }
245 }
246 decoration_runs.push(DecorationRun {
247 len: run.len as u32,
248 color: run.color,
249 background_color: run.background_color,
250 underline: run.underline,
251 });
252 }
253
254 let layout = self.layout_line(text.as_ref(), font_size, runs)?;
255
256 Ok(ShapedLine {
257 layout,
258 text,
259 decoration_runs,
260 })
261 }
262
263 pub fn shape_text(
264 &self,
265 text: SharedString,
266 font_size: Pixels,
267 runs: &[TextRun],
268 wrap_width: Option<Pixels>,
269 ) -> Result<SmallVec<[WrappedLine; 1]>> {
270 let mut runs = runs.iter().cloned().peekable();
271 let mut font_runs = self.font_runs_pool.lock().pop().unwrap_or_default();
272
273 let mut lines = SmallVec::new();
274 let mut line_start = 0;
275
276 let mut process_line = |line_text: SharedString| {
277 let line_end = line_start + line_text.len();
278
279 let mut last_font: Option<Font> = None;
280 let mut decoration_runs = SmallVec::<[DecorationRun; 32]>::new();
281 let mut run_start = line_start;
282 while run_start < line_end {
283 let Some(run) = runs.peek_mut() else {
284 break;
285 };
286
287 let run_len_within_line = cmp::min(line_end, run_start + run.len) - run_start;
288
289 if last_font == Some(run.font.clone()) {
290 font_runs.last_mut().unwrap().len += run_len_within_line;
291 } else {
292 last_font = Some(run.font.clone());
293 font_runs.push(FontRun {
294 len: run_len_within_line,
295 font_id: self.resolve_font(&run.font),
296 });
297 }
298
299 if decoration_runs.last().map_or(false, |last_run| {
300 last_run.color == run.color
301 && last_run.underline == run.underline
302 && last_run.background_color == run.background_color
303 }) {
304 decoration_runs.last_mut().unwrap().len += run_len_within_line as u32;
305 } else {
306 decoration_runs.push(DecorationRun {
307 len: run_len_within_line as u32,
308 color: run.color,
309 background_color: run.background_color,
310 underline: run.underline,
311 });
312 }
313
314 if run_len_within_line == run.len {
315 runs.next();
316 } else {
317 // Preserve the remainder of the run for the next line
318 run.len -= run_len_within_line;
319 }
320 run_start += run_len_within_line;
321 }
322
323 let layout = self
324 .line_layout_cache
325 .layout_wrapped_line(&line_text, font_size, &font_runs, wrap_width);
326 lines.push(WrappedLine {
327 layout,
328 decoration_runs,
329 text: line_text,
330 });
331
332 // Skip `\n` character.
333 line_start = line_end + 1;
334 if let Some(run) = runs.peek_mut() {
335 run.len = run.len.saturating_sub(1);
336 if run.len == 0 {
337 runs.next();
338 }
339 }
340
341 font_runs.clear();
342 };
343
344 let mut split_lines = text.split('\n');
345 let mut processed = false;
346
347 if let Some(first_line) = split_lines.next() {
348 if let Some(second_line) = split_lines.next() {
349 processed = true;
350 process_line(first_line.to_string().into());
351 process_line(second_line.to_string().into());
352 for line_text in split_lines {
353 process_line(line_text.to_string().into());
354 }
355 }
356 }
357
358 if !processed {
359 process_line(text);
360 }
361
362 self.font_runs_pool.lock().push(font_runs);
363
364 Ok(lines)
365 }
366
367 pub fn finish_frame(&self, reused_views: &FxHashSet<EntityId>) {
368 self.line_layout_cache.finish_frame(reused_views)
369 }
370
371 pub fn line_wrapper(
372 self: &Arc<Self>,
373 font: Font,
374 font_size: Pixels,
375 ) -> Result<LineWrapperHandle> {
376 let lock = &mut self.wrapper_pool.lock();
377 let font_id = self.font_id(&font)?;
378 let wrappers = lock
379 .entry(FontIdWithSize { font_id, font_size })
380 .or_default();
381 let wrapper = wrappers.pop().map(anyhow::Ok).unwrap_or_else(|| {
382 Ok(LineWrapper::new(
383 font_id,
384 font_size,
385 self.platform_text_system.clone(),
386 ))
387 })?;
388
389 Ok(LineWrapperHandle {
390 wrapper: Some(wrapper),
391 text_system: self.clone(),
392 })
393 }
394
395 pub fn raster_bounds(&self, params: &RenderGlyphParams) -> Result<Bounds<DevicePixels>> {
396 let raster_bounds = self.raster_bounds.upgradable_read();
397 if let Some(bounds) = raster_bounds.get(params) {
398 Ok(*bounds)
399 } else {
400 let mut raster_bounds = RwLockUpgradableReadGuard::upgrade(raster_bounds);
401 let bounds = self.platform_text_system.glyph_raster_bounds(params)?;
402 raster_bounds.insert(params.clone(), bounds);
403 Ok(bounds)
404 }
405 }
406
407 pub fn rasterize_glyph(
408 &self,
409 params: &RenderGlyphParams,
410 ) -> Result<(Size<DevicePixels>, Vec<u8>)> {
411 let raster_bounds = self.raster_bounds(params)?;
412 self.platform_text_system
413 .rasterize_glyph(params, raster_bounds)
414 }
415}
416
417#[derive(Hash, Eq, PartialEq)]
418struct FontIdWithSize {
419 font_id: FontId,
420 font_size: Pixels,
421}
422
423pub struct LineWrapperHandle {
424 wrapper: Option<LineWrapper>,
425 text_system: Arc<TextSystem>,
426}
427
428impl Drop for LineWrapperHandle {
429 fn drop(&mut self) {
430 let mut state = self.text_system.wrapper_pool.lock();
431 let wrapper = self.wrapper.take().unwrap();
432 state
433 .get_mut(&FontIdWithSize {
434 font_id: wrapper.font_id,
435 font_size: wrapper.font_size,
436 })
437 .unwrap()
438 .push(wrapper);
439 }
440}
441
442impl Deref for LineWrapperHandle {
443 type Target = LineWrapper;
444
445 fn deref(&self) -> &Self::Target {
446 self.wrapper.as_ref().unwrap()
447 }
448}
449
450impl DerefMut for LineWrapperHandle {
451 fn deref_mut(&mut self) -> &mut Self::Target {
452 self.wrapper.as_mut().unwrap()
453 }
454}
455
456/// The degree of blackness or stroke thickness of a font. This value ranges from 100.0 to 900.0,
457/// with 400.0 as normal.
458#[derive(Clone, Copy, Debug, PartialEq, PartialOrd)]
459pub struct FontWeight(pub f32);
460
461impl Default for FontWeight {
462 #[inline]
463 fn default() -> FontWeight {
464 FontWeight::NORMAL
465 }
466}
467
468impl Hash for FontWeight {
469 fn hash<H: Hasher>(&self, state: &mut H) {
470 state.write_u32(u32::from_be_bytes(self.0.to_be_bytes()));
471 }
472}
473
474impl Eq for FontWeight {}
475
476impl FontWeight {
477 /// Thin weight (100), the thinnest value.
478 pub const THIN: FontWeight = FontWeight(100.0);
479 /// Extra light weight (200).
480 pub const EXTRA_LIGHT: FontWeight = FontWeight(200.0);
481 /// Light weight (300).
482 pub const LIGHT: FontWeight = FontWeight(300.0);
483 /// Normal (400).
484 pub const NORMAL: FontWeight = FontWeight(400.0);
485 /// Medium weight (500, higher than normal).
486 pub const MEDIUM: FontWeight = FontWeight(500.0);
487 /// Semibold weight (600).
488 pub const SEMIBOLD: FontWeight = FontWeight(600.0);
489 /// Bold weight (700).
490 pub const BOLD: FontWeight = FontWeight(700.0);
491 /// Extra-bold weight (800).
492 pub const EXTRA_BOLD: FontWeight = FontWeight(800.0);
493 /// Black weight (900), the thickest value.
494 pub const BLACK: FontWeight = FontWeight(900.0);
495}
496
497/// Allows italic or oblique faces to be selected.
498#[derive(Clone, Copy, Eq, PartialEq, Debug, Hash, Default)]
499pub enum FontStyle {
500 /// A face that is neither italic not obliqued.
501 #[default]
502 Normal,
503 /// A form that is generally cursive in nature.
504 Italic,
505 /// A typically-sloped version of the regular face.
506 Oblique,
507}
508
509impl Display for FontStyle {
510 fn fmt(&self, f: &mut Formatter) -> fmt::Result {
511 Debug::fmt(self, f)
512 }
513}
514
515#[derive(Clone, Debug, PartialEq, Eq)]
516pub struct TextRun {
517 // number of utf8 bytes
518 pub len: usize,
519 pub font: Font,
520 pub color: Hsla,
521 pub background_color: Option<Hsla>,
522 pub underline: Option<UnderlineStyle>,
523}
524
525#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
526#[repr(C)]
527pub struct GlyphId(u32);
528
529impl From<GlyphId> for u32 {
530 fn from(value: GlyphId) -> Self {
531 value.0
532 }
533}
534
535impl From<u16> for GlyphId {
536 fn from(num: u16) -> Self {
537 GlyphId(num as u32)
538 }
539}
540
541impl From<u32> for GlyphId {
542 fn from(num: u32) -> Self {
543 GlyphId(num)
544 }
545}
546
547#[derive(Clone, Debug, PartialEq)]
548pub struct RenderGlyphParams {
549 pub(crate) font_id: FontId,
550 pub(crate) glyph_id: GlyphId,
551 pub(crate) font_size: Pixels,
552 pub(crate) subpixel_variant: Point<u8>,
553 pub(crate) scale_factor: f32,
554 pub(crate) is_emoji: bool,
555}
556
557impl Eq for RenderGlyphParams {}
558
559impl Hash for RenderGlyphParams {
560 fn hash<H: Hasher>(&self, state: &mut H) {
561 self.font_id.0.hash(state);
562 self.glyph_id.0.hash(state);
563 self.font_size.0.to_bits().hash(state);
564 self.subpixel_variant.hash(state);
565 self.scale_factor.to_bits().hash(state);
566 }
567}
568
569#[derive(Clone, Debug, PartialEq)]
570pub struct RenderEmojiParams {
571 pub(crate) font_id: FontId,
572 pub(crate) glyph_id: GlyphId,
573 pub(crate) font_size: Pixels,
574 pub(crate) scale_factor: f32,
575}
576
577impl Eq for RenderEmojiParams {}
578
579impl Hash for RenderEmojiParams {
580 fn hash<H: Hasher>(&self, state: &mut H) {
581 self.font_id.0.hash(state);
582 self.glyph_id.0.hash(state);
583 self.font_size.0.to_bits().hash(state);
584 self.scale_factor.to_bits().hash(state);
585 }
586}
587
588#[derive(Clone, Debug, Eq, PartialEq, Hash)]
589pub struct Font {
590 pub family: SharedString,
591 pub features: FontFeatures,
592 pub weight: FontWeight,
593 pub style: FontStyle,
594}
595
596pub fn font(family: impl Into<SharedString>) -> Font {
597 Font {
598 family: family.into(),
599 features: FontFeatures::default(),
600 weight: FontWeight::default(),
601 style: FontStyle::default(),
602 }
603}
604
605impl Font {
606 pub fn bold(mut self) -> Self {
607 self.weight = FontWeight::BOLD;
608 self
609 }
610}
611
612/// A struct for storing font metrics.
613/// It is used to define the measurements of a typeface.
614#[derive(Clone, Copy, Debug)]
615pub struct FontMetrics {
616 /// The number of font units that make up the "em square",
617 /// a scalable grid for determining the size of a typeface.
618 pub(crate) units_per_em: u32,
619
620 /// The vertical distance from the baseline of the font to the top of the glyph covers.
621 pub(crate) ascent: f32,
622
623 /// The vertical distance from the baseline of the font to the bottom of the glyph covers.
624 pub(crate) descent: f32,
625
626 /// The recommended additional space to add between lines of type.
627 pub(crate) line_gap: f32,
628
629 /// The suggested position of the underline.
630 pub(crate) underline_position: f32,
631
632 /// The suggested thickness of the underline.
633 pub(crate) underline_thickness: f32,
634
635 /// The height of a capital letter measured from the baseline of the font.
636 pub(crate) cap_height: f32,
637
638 /// The height of a lowercase x.
639 pub(crate) x_height: f32,
640
641 /// The outer limits of the area that the font covers.
642 pub(crate) bounding_box: Bounds<f32>,
643}
644
645impl FontMetrics {
646 /// Returns the vertical distance from the baseline of the font to the top of the glyph covers in pixels.
647 pub fn ascent(&self, font_size: Pixels) -> Pixels {
648 Pixels((self.ascent / self.units_per_em as f32) * font_size.0)
649 }
650
651 /// Returns the vertical distance from the baseline of the font to the bottom of the glyph covers in pixels.
652 pub fn descent(&self, font_size: Pixels) -> Pixels {
653 Pixels((self.descent / self.units_per_em as f32) * font_size.0)
654 }
655
656 /// Returns the recommended additional space to add between lines of type in pixels.
657 pub fn line_gap(&self, font_size: Pixels) -> Pixels {
658 Pixels((self.line_gap / self.units_per_em as f32) * font_size.0)
659 }
660
661 /// Returns the suggested position of the underline in pixels.
662 pub fn underline_position(&self, font_size: Pixels) -> Pixels {
663 Pixels((self.underline_position / self.units_per_em as f32) * font_size.0)
664 }
665
666 /// Returns the suggested thickness of the underline in pixels.
667 pub fn underline_thickness(&self, font_size: Pixels) -> Pixels {
668 Pixels((self.underline_thickness / self.units_per_em as f32) * font_size.0)
669 }
670
671 /// Returns the height of a capital letter measured from the baseline of the font in pixels.
672 pub fn cap_height(&self, font_size: Pixels) -> Pixels {
673 Pixels((self.cap_height / self.units_per_em as f32) * font_size.0)
674 }
675
676 /// Returns the height of a lowercase x in pixels.
677 pub fn x_height(&self, font_size: Pixels) -> Pixels {
678 Pixels((self.x_height / self.units_per_em as f32) * font_size.0)
679 }
680
681 /// Returns the outer limits of the area that the font covers in pixels.
682 pub fn bounding_box(&self, font_size: Pixels) -> Bounds<Pixels> {
683 (self.bounding_box / self.units_per_em as f32 * font_size.0).map(px)
684 }
685}