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