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::{BTreeSet, 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(crate) 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 all_font_names(&self) -> Vec<String> {
69 let mut names: BTreeSet<_> = self
70 .platform_text_system
71 .all_font_names()
72 .into_iter()
73 .collect();
74 names.extend(self.platform_text_system.all_font_families().into_iter());
75 names.extend(
76 self.fallback_font_stack
77 .iter()
78 .map(|font| font.family.to_string()),
79 );
80 names.into_iter().collect()
81 }
82 pub fn add_fonts(&self, fonts: &[Arc<Vec<u8>>]) -> Result<()> {
83 self.platform_text_system.add_fonts(fonts)
84 }
85
86 pub fn font_id(&self, font: &Font) -> Result<FontId> {
87 let font_id = self.font_ids_by_font.read().get(font).copied();
88 if let Some(font_id) = font_id {
89 Ok(font_id)
90 } else {
91 let font_id = self.platform_text_system.font_id(font)?;
92 self.font_ids_by_font.write().insert(font.clone(), font_id);
93 Ok(font_id)
94 }
95 }
96
97 /// Resolves the specified font, falling back to the default font stack if
98 /// the font fails to load.
99 ///
100 /// # Panics
101 ///
102 /// Panics if the font and none of the fallbacks can be resolved.
103 pub fn resolve_font(&self, font: &Font) -> FontId {
104 if let Ok(font_id) = self.font_id(font) {
105 return font_id;
106 }
107 for fallback in &self.fallback_font_stack {
108 if let Ok(font_id) = self.font_id(fallback) {
109 return font_id;
110 }
111 }
112
113 panic!(
114 "failed to resolve font '{}' or any of the fallbacks: {}",
115 font.family,
116 self.fallback_font_stack
117 .iter()
118 .map(|fallback| &fallback.family)
119 .join(", ")
120 );
121 }
122
123 pub fn bounding_box(&self, font_id: FontId, font_size: Pixels) -> Bounds<Pixels> {
124 self.read_metrics(font_id, |metrics| metrics.bounding_box(font_size))
125 }
126
127 pub fn typographic_bounds(
128 &self,
129 font_id: FontId,
130 font_size: Pixels,
131 character: char,
132 ) -> Result<Bounds<Pixels>> {
133 let glyph_id = self
134 .platform_text_system
135 .glyph_for_char(font_id, character)
136 .ok_or_else(|| anyhow!("glyph not found for character '{}'", character))?;
137 let bounds = self
138 .platform_text_system
139 .typographic_bounds(font_id, glyph_id)?;
140 Ok(self.read_metrics(font_id, |metrics| {
141 (bounds / metrics.units_per_em as f32 * font_size.0).map(px)
142 }))
143 }
144
145 pub fn advance(&self, font_id: FontId, font_size: Pixels, ch: char) -> Result<Size<Pixels>> {
146 let glyph_id = self
147 .platform_text_system
148 .glyph_for_char(font_id, ch)
149 .ok_or_else(|| anyhow!("glyph not found for character '{}'", ch))?;
150 let result = self.platform_text_system.advance(font_id, glyph_id)?
151 / self.units_per_em(font_id) as f32;
152
153 Ok(result * font_size)
154 }
155
156 pub fn units_per_em(&self, font_id: FontId) -> u32 {
157 self.read_metrics(font_id, |metrics| metrics.units_per_em)
158 }
159
160 pub fn cap_height(&self, font_id: FontId, font_size: Pixels) -> Pixels {
161 self.read_metrics(font_id, |metrics| metrics.cap_height(font_size))
162 }
163
164 pub fn x_height(&self, font_id: FontId, font_size: Pixels) -> Pixels {
165 self.read_metrics(font_id, |metrics| metrics.x_height(font_size))
166 }
167
168 pub fn ascent(&self, font_id: FontId, font_size: Pixels) -> Pixels {
169 self.read_metrics(font_id, |metrics| metrics.ascent(font_size))
170 }
171
172 pub fn descent(&self, font_id: FontId, font_size: Pixels) -> Pixels {
173 self.read_metrics(font_id, |metrics| metrics.descent(font_size))
174 }
175
176 pub fn baseline_offset(
177 &self,
178 font_id: FontId,
179 font_size: Pixels,
180 line_height: Pixels,
181 ) -> Pixels {
182 let ascent = self.ascent(font_id, font_size);
183 let descent = self.descent(font_id, font_size);
184 let padding_top = (line_height - ascent - descent) / 2.;
185 padding_top + ascent
186 }
187
188 fn read_metrics<T>(&self, font_id: FontId, read: impl FnOnce(&FontMetrics) -> T) -> T {
189 let lock = self.font_metrics.upgradable_read();
190
191 if let Some(metrics) = lock.get(&font_id) {
192 read(metrics)
193 } else {
194 let mut lock = RwLockUpgradableReadGuard::upgrade(lock);
195 let metrics = lock
196 .entry(font_id)
197 .or_insert_with(|| self.platform_text_system.font_metrics(font_id));
198 read(metrics)
199 }
200 }
201
202 pub fn with_view<R>(&self, view_id: EntityId, f: impl FnOnce() -> R) -> R {
203 self.line_layout_cache.with_view(view_id, f)
204 }
205
206 pub fn layout_line(
207 &self,
208 text: &str,
209 font_size: Pixels,
210 runs: &[TextRun],
211 ) -> Result<Arc<LineLayout>> {
212 let mut font_runs = self.font_runs_pool.lock().pop().unwrap_or_default();
213 for run in runs.iter() {
214 let font_id = self.resolve_font(&run.font);
215 if let Some(last_run) = font_runs.last_mut() {
216 if last_run.font_id == font_id {
217 last_run.len += run.len;
218 continue;
219 }
220 }
221 font_runs.push(FontRun {
222 len: run.len,
223 font_id,
224 });
225 }
226
227 let layout = self
228 .line_layout_cache
229 .layout_line(text, font_size, &font_runs);
230
231 font_runs.clear();
232 self.font_runs_pool.lock().push(font_runs);
233
234 Ok(layout)
235 }
236
237 pub fn shape_line(
238 &self,
239 text: SharedString,
240 font_size: Pixels,
241 runs: &[TextRun],
242 ) -> Result<ShapedLine> {
243 debug_assert!(
244 text.find('\n').is_none(),
245 "text argument should not contain newlines"
246 );
247
248 let mut decoration_runs = SmallVec::<[DecorationRun; 32]>::new();
249 for run in runs {
250 if let Some(last_run) = decoration_runs.last_mut() {
251 if last_run.color == run.color
252 && last_run.underline == run.underline
253 && last_run.background_color == run.background_color
254 {
255 last_run.len += run.len as u32;
256 continue;
257 }
258 }
259 decoration_runs.push(DecorationRun {
260 len: run.len as u32,
261 color: run.color,
262 background_color: run.background_color,
263 underline: run.underline,
264 });
265 }
266
267 let layout = self.layout_line(text.as_ref(), font_size, runs)?;
268
269 Ok(ShapedLine {
270 layout,
271 text,
272 decoration_runs,
273 })
274 }
275
276 pub fn shape_text(
277 &self,
278 text: SharedString,
279 font_size: Pixels,
280 runs: &[TextRun],
281 wrap_width: Option<Pixels>,
282 ) -> Result<SmallVec<[WrappedLine; 1]>> {
283 let mut runs = runs.iter().cloned().peekable();
284 let mut font_runs = self.font_runs_pool.lock().pop().unwrap_or_default();
285
286 let mut lines = SmallVec::new();
287 let mut line_start = 0;
288
289 let mut process_line = |line_text: SharedString| {
290 let line_end = line_start + line_text.len();
291
292 let mut last_font: Option<Font> = None;
293 let mut decoration_runs = SmallVec::<[DecorationRun; 32]>::new();
294 let mut run_start = line_start;
295 while run_start < line_end {
296 let Some(run) = runs.peek_mut() else {
297 break;
298 };
299
300 let run_len_within_line = cmp::min(line_end, run_start + run.len) - run_start;
301
302 if last_font == Some(run.font.clone()) {
303 font_runs.last_mut().unwrap().len += run_len_within_line;
304 } else {
305 last_font = Some(run.font.clone());
306 font_runs.push(FontRun {
307 len: run_len_within_line,
308 font_id: self.resolve_font(&run.font),
309 });
310 }
311
312 if decoration_runs.last().map_or(false, |last_run| {
313 last_run.color == run.color
314 && last_run.underline == run.underline
315 && last_run.background_color == run.background_color
316 }) {
317 decoration_runs.last_mut().unwrap().len += run_len_within_line as u32;
318 } else {
319 decoration_runs.push(DecorationRun {
320 len: run_len_within_line as u32,
321 color: run.color,
322 background_color: run.background_color,
323 underline: run.underline,
324 });
325 }
326
327 if run_len_within_line == run.len {
328 runs.next();
329 } else {
330 // Preserve the remainder of the run for the next line
331 run.len -= run_len_within_line;
332 }
333 run_start += run_len_within_line;
334 }
335
336 let layout = self
337 .line_layout_cache
338 .layout_wrapped_line(&line_text, font_size, &font_runs, wrap_width);
339 lines.push(WrappedLine {
340 layout,
341 decoration_runs,
342 text: line_text,
343 });
344
345 // Skip `\n` character.
346 line_start = line_end + 1;
347 if let Some(run) = runs.peek_mut() {
348 run.len = run.len.saturating_sub(1);
349 if run.len == 0 {
350 runs.next();
351 }
352 }
353
354 font_runs.clear();
355 };
356
357 let mut split_lines = text.split('\n');
358 let mut processed = false;
359
360 if let Some(first_line) = split_lines.next() {
361 if let Some(second_line) = split_lines.next() {
362 processed = true;
363 process_line(first_line.to_string().into());
364 process_line(second_line.to_string().into());
365 for line_text in split_lines {
366 process_line(line_text.to_string().into());
367 }
368 }
369 }
370
371 if !processed {
372 process_line(text);
373 }
374
375 self.font_runs_pool.lock().push(font_runs);
376
377 Ok(lines)
378 }
379
380 pub fn finish_frame(&self, reused_views: &FxHashSet<EntityId>) {
381 self.line_layout_cache.finish_frame(reused_views)
382 }
383
384 pub fn line_wrapper(self: &Arc<Self>, font: Font, font_size: Pixels) -> LineWrapperHandle {
385 let lock = &mut self.wrapper_pool.lock();
386 let font_id = self.resolve_font(&font);
387 let wrappers = lock
388 .entry(FontIdWithSize { font_id, font_size })
389 .or_default();
390 let wrapper = wrappers.pop().unwrap_or_else(|| {
391 LineWrapper::new(font_id, font_size, self.platform_text_system.clone())
392 });
393
394 LineWrapperHandle {
395 wrapper: Some(wrapper),
396 text_system: self.clone(),
397 }
398 }
399
400 pub fn raster_bounds(&self, params: &RenderGlyphParams) -> Result<Bounds<DevicePixels>> {
401 let raster_bounds = self.raster_bounds.upgradable_read();
402 if let Some(bounds) = raster_bounds.get(params) {
403 Ok(*bounds)
404 } else {
405 let mut raster_bounds = RwLockUpgradableReadGuard::upgrade(raster_bounds);
406 let bounds = self.platform_text_system.glyph_raster_bounds(params)?;
407 raster_bounds.insert(params.clone(), bounds);
408 Ok(bounds)
409 }
410 }
411
412 pub fn rasterize_glyph(
413 &self,
414 params: &RenderGlyphParams,
415 ) -> Result<(Size<DevicePixels>, Vec<u8>)> {
416 let raster_bounds = self.raster_bounds(params)?;
417 self.platform_text_system
418 .rasterize_glyph(params, raster_bounds)
419 }
420}
421
422#[derive(Hash, Eq, PartialEq)]
423struct FontIdWithSize {
424 font_id: FontId,
425 font_size: Pixels,
426}
427
428pub struct LineWrapperHandle {
429 wrapper: Option<LineWrapper>,
430 text_system: Arc<TextSystem>,
431}
432
433impl Drop for LineWrapperHandle {
434 fn drop(&mut self) {
435 let mut state = self.text_system.wrapper_pool.lock();
436 let wrapper = self.wrapper.take().unwrap();
437 state
438 .get_mut(&FontIdWithSize {
439 font_id: wrapper.font_id,
440 font_size: wrapper.font_size,
441 })
442 .unwrap()
443 .push(wrapper);
444 }
445}
446
447impl Deref for LineWrapperHandle {
448 type Target = LineWrapper;
449
450 fn deref(&self) -> &Self::Target {
451 self.wrapper.as_ref().unwrap()
452 }
453}
454
455impl DerefMut for LineWrapperHandle {
456 fn deref_mut(&mut self) -> &mut Self::Target {
457 self.wrapper.as_mut().unwrap()
458 }
459}
460
461/// The degree of blackness or stroke thickness of a font. This value ranges from 100.0 to 900.0,
462/// with 400.0 as normal.
463#[derive(Clone, Copy, Debug, PartialEq, PartialOrd)]
464pub struct FontWeight(pub f32);
465
466impl Default for FontWeight {
467 #[inline]
468 fn default() -> FontWeight {
469 FontWeight::NORMAL
470 }
471}
472
473impl Hash for FontWeight {
474 fn hash<H: Hasher>(&self, state: &mut H) {
475 state.write_u32(u32::from_be_bytes(self.0.to_be_bytes()));
476 }
477}
478
479impl Eq for FontWeight {}
480
481impl FontWeight {
482 /// Thin weight (100), the thinnest value.
483 pub const THIN: FontWeight = FontWeight(100.0);
484 /// Extra light weight (200).
485 pub const EXTRA_LIGHT: FontWeight = FontWeight(200.0);
486 /// Light weight (300).
487 pub const LIGHT: FontWeight = FontWeight(300.0);
488 /// Normal (400).
489 pub const NORMAL: FontWeight = FontWeight(400.0);
490 /// Medium weight (500, higher than normal).
491 pub const MEDIUM: FontWeight = FontWeight(500.0);
492 /// Semibold weight (600).
493 pub const SEMIBOLD: FontWeight = FontWeight(600.0);
494 /// Bold weight (700).
495 pub const BOLD: FontWeight = FontWeight(700.0);
496 /// Extra-bold weight (800).
497 pub const EXTRA_BOLD: FontWeight = FontWeight(800.0);
498 /// Black weight (900), the thickest value.
499 pub const BLACK: FontWeight = FontWeight(900.0);
500}
501
502/// Allows italic or oblique faces to be selected.
503#[derive(Clone, Copy, Eq, PartialEq, Debug, Hash, Default)]
504pub enum FontStyle {
505 /// A face that is neither italic not obliqued.
506 #[default]
507 Normal,
508 /// A form that is generally cursive in nature.
509 Italic,
510 /// A typically-sloped version of the regular face.
511 Oblique,
512}
513
514impl Display for FontStyle {
515 fn fmt(&self, f: &mut Formatter) -> fmt::Result {
516 Debug::fmt(self, f)
517 }
518}
519
520#[derive(Clone, Debug, PartialEq, Eq)]
521pub struct TextRun {
522 // number of utf8 bytes
523 pub len: usize,
524 pub font: Font,
525 pub color: Hsla,
526 pub background_color: Option<Hsla>,
527 pub underline: Option<UnderlineStyle>,
528}
529
530#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
531#[repr(C)]
532pub struct GlyphId(u32);
533
534impl From<GlyphId> for u32 {
535 fn from(value: GlyphId) -> Self {
536 value.0
537 }
538}
539
540impl From<u16> for GlyphId {
541 fn from(num: u16) -> Self {
542 GlyphId(num as u32)
543 }
544}
545
546impl From<u32> for GlyphId {
547 fn from(num: u32) -> Self {
548 GlyphId(num)
549 }
550}
551
552#[derive(Clone, Debug, PartialEq)]
553pub struct RenderGlyphParams {
554 pub(crate) font_id: FontId,
555 pub(crate) glyph_id: GlyphId,
556 pub(crate) font_size: Pixels,
557 pub(crate) subpixel_variant: Point<u8>,
558 pub(crate) scale_factor: f32,
559 pub(crate) is_emoji: bool,
560}
561
562impl Eq for RenderGlyphParams {}
563
564impl Hash for RenderGlyphParams {
565 fn hash<H: Hasher>(&self, state: &mut H) {
566 self.font_id.0.hash(state);
567 self.glyph_id.0.hash(state);
568 self.font_size.0.to_bits().hash(state);
569 self.subpixel_variant.hash(state);
570 self.scale_factor.to_bits().hash(state);
571 }
572}
573
574#[derive(Clone, Debug, PartialEq)]
575pub struct RenderEmojiParams {
576 pub(crate) font_id: FontId,
577 pub(crate) glyph_id: GlyphId,
578 pub(crate) font_size: Pixels,
579 pub(crate) scale_factor: f32,
580}
581
582impl Eq for RenderEmojiParams {}
583
584impl Hash for RenderEmojiParams {
585 fn hash<H: Hasher>(&self, state: &mut H) {
586 self.font_id.0.hash(state);
587 self.glyph_id.0.hash(state);
588 self.font_size.0.to_bits().hash(state);
589 self.scale_factor.to_bits().hash(state);
590 }
591}
592
593#[derive(Clone, Debug, Eq, PartialEq, Hash)]
594pub struct Font {
595 pub family: SharedString,
596 pub features: FontFeatures,
597 pub weight: FontWeight,
598 pub style: FontStyle,
599}
600
601pub fn font(family: impl Into<SharedString>) -> Font {
602 Font {
603 family: family.into(),
604 features: FontFeatures::default(),
605 weight: FontWeight::default(),
606 style: FontStyle::default(),
607 }
608}
609
610impl Font {
611 pub fn bold(mut self) -> Self {
612 self.weight = FontWeight::BOLD;
613 self
614 }
615}
616
617/// A struct for storing font metrics.
618/// It is used to define the measurements of a typeface.
619#[derive(Clone, Copy, Debug)]
620pub struct FontMetrics {
621 /// The number of font units that make up the "em square",
622 /// a scalable grid for determining the size of a typeface.
623 pub(crate) units_per_em: u32,
624
625 /// The vertical distance from the baseline of the font to the top of the glyph covers.
626 pub(crate) ascent: f32,
627
628 /// The vertical distance from the baseline of the font to the bottom of the glyph covers.
629 pub(crate) descent: f32,
630
631 /// The recommended additional space to add between lines of type.
632 pub(crate) line_gap: f32,
633
634 /// The suggested position of the underline.
635 pub(crate) underline_position: f32,
636
637 /// The suggested thickness of the underline.
638 pub(crate) underline_thickness: f32,
639
640 /// The height of a capital letter measured from the baseline of the font.
641 pub(crate) cap_height: f32,
642
643 /// The height of a lowercase x.
644 pub(crate) x_height: f32,
645
646 /// The outer limits of the area that the font covers.
647 pub(crate) bounding_box: Bounds<f32>,
648}
649
650impl FontMetrics {
651 /// Returns the vertical distance from the baseline of the font to the top of the glyph covers in pixels.
652 pub fn ascent(&self, font_size: Pixels) -> Pixels {
653 Pixels((self.ascent / self.units_per_em as f32) * font_size.0)
654 }
655
656 /// Returns the vertical distance from the baseline of the font to the bottom of the glyph covers in pixels.
657 pub fn descent(&self, font_size: Pixels) -> Pixels {
658 Pixels((self.descent / self.units_per_em as f32) * font_size.0)
659 }
660
661 /// Returns the recommended additional space to add between lines of type in pixels.
662 pub fn line_gap(&self, font_size: Pixels) -> Pixels {
663 Pixels((self.line_gap / self.units_per_em as f32) * font_size.0)
664 }
665
666 /// Returns the suggested position of the underline in pixels.
667 pub fn underline_position(&self, font_size: Pixels) -> Pixels {
668 Pixels((self.underline_position / self.units_per_em as f32) * font_size.0)
669 }
670
671 /// Returns the suggested thickness of the underline in pixels.
672 pub fn underline_thickness(&self, font_size: Pixels) -> Pixels {
673 Pixels((self.underline_thickness / self.units_per_em as f32) * font_size.0)
674 }
675
676 /// Returns the height of a capital letter measured from the baseline of the font in pixels.
677 pub fn cap_height(&self, font_size: Pixels) -> Pixels {
678 Pixels((self.cap_height / self.units_per_em as f32) * font_size.0)
679 }
680
681 /// Returns the height of a lowercase x in pixels.
682 pub fn x_height(&self, font_size: Pixels) -> Pixels {
683 Pixels((self.x_height / self.units_per_em as f32) * font_size.0)
684 }
685
686 /// Returns the outer limits of the area that the font covers in pixels.
687 pub fn bounding_box(&self, font_size: Pixels) -> Bounds<Pixels> {
688 (self.bounding_box / self.units_per_em as f32 * font_size.0).map(px)
689 }
690}