1mod font_fallbacks;
2mod font_features;
3mod line;
4mod line_layout;
5mod line_wrapper;
6
7pub use font_fallbacks::*;
8pub use font_features::*;
9pub use line::*;
10pub use line_layout::*;
11pub use line_wrapper::*;
12use schemars::JsonSchema;
13use serde::{Deserialize, Serialize};
14
15use crate::{
16 Bounds, DevicePixels, Hsla, Pixels, PlatformTextSystem, Point, Result, SharedString, Size,
17 StrikethroughStyle, UnderlineStyle, px,
18};
19use anyhow::{Context as _, anyhow};
20use collections::FxHashMap;
21use core::fmt;
22use derive_more::Deref;
23use itertools::Itertools;
24use parking_lot::{Mutex, RwLock, RwLockUpgradableReadGuard};
25use smallvec::{SmallVec, smallvec};
26use std::{
27 borrow::Cow,
28 cmp,
29 fmt::{Debug, Display, Formatter},
30 hash::{Hash, Hasher},
31 ops::{Deref, DerefMut, Range},
32 sync::Arc,
33};
34
35/// An opaque identifier for a specific font.
36#[derive(Hash, PartialEq, Eq, Clone, Copy, Debug)]
37#[repr(C)]
38pub struct FontId(pub usize);
39
40/// An opaque identifier for a specific font family.
41#[derive(Hash, PartialEq, Eq, Clone, Copy, Debug)]
42pub struct FontFamilyId(pub usize);
43
44pub(crate) const SUBPIXEL_VARIANTS: u8 = 4;
45
46/// The GPUI text rendering sub system.
47pub struct TextSystem {
48 platform_text_system: Arc<dyn PlatformTextSystem>,
49 font_ids_by_font: RwLock<FxHashMap<Font, Result<FontId>>>,
50 font_metrics: RwLock<FxHashMap<FontId, FontMetrics>>,
51 raster_bounds: RwLock<FxHashMap<RenderGlyphParams, Bounds<DevicePixels>>>,
52 wrapper_pool: Mutex<FxHashMap<FontIdWithSize, Vec<LineWrapper>>>,
53 font_runs_pool: Mutex<Vec<Vec<FontRun>>>,
54 fallback_font_stack: SmallVec<[Font; 2]>,
55}
56
57impl TextSystem {
58 pub(crate) fn new(platform_text_system: Arc<dyn PlatformTextSystem>) -> Self {
59 TextSystem {
60 platform_text_system,
61 font_metrics: RwLock::default(),
62 raster_bounds: RwLock::default(),
63 font_ids_by_font: RwLock::default(),
64 wrapper_pool: Mutex::default(),
65 font_runs_pool: Mutex::default(),
66 fallback_font_stack: smallvec![
67 // TODO: Remove this when Linux have implemented setting fallbacks.
68 font("Zed Plex Mono"),
69 font("Helvetica"),
70 font("Segoe UI"), // Windows
71 font("Cantarell"), // Gnome
72 font("Ubuntu"), // Gnome (Ubuntu)
73 font("Noto Sans"), // KDE
74 font("DejaVu Sans")
75 ],
76 }
77 }
78
79 /// Get a list of all available font names from the operating system.
80 pub fn all_font_names(&self) -> Vec<String> {
81 let mut names = self.platform_text_system.all_font_names();
82 names.extend(
83 self.fallback_font_stack
84 .iter()
85 .map(|font| font.family.to_string()),
86 );
87 names.push(".SystemUIFont".to_string());
88 names.sort();
89 names.dedup();
90 names
91 }
92
93 /// Add a font's data to the text system.
94 pub fn add_fonts(&self, fonts: Vec<Cow<'static, [u8]>>) -> Result<()> {
95 self.platform_text_system.add_fonts(fonts)
96 }
97
98 /// Get the FontId for the configure font family and style.
99 pub fn font_id(&self, font: &Font) -> Result<FontId> {
100 fn clone_font_id_result(font_id: &Result<FontId>) -> Result<FontId> {
101 match font_id {
102 Ok(font_id) => Ok(*font_id),
103 Err(err) => Err(anyhow!("{err}")),
104 }
105 }
106
107 let font_id = self
108 .font_ids_by_font
109 .read()
110 .get(font)
111 .map(clone_font_id_result);
112 if let Some(font_id) = font_id {
113 font_id
114 } else {
115 let font_id = self.platform_text_system.font_id(font);
116 self.font_ids_by_font
117 .write()
118 .insert(font.clone(), clone_font_id_result(&font_id));
119 font_id
120 }
121 }
122
123 /// Get the Font for the Font Id.
124 pub fn get_font_for_id(&self, id: FontId) -> Option<Font> {
125 let lock = self.font_ids_by_font.read();
126 lock.iter()
127 .filter_map(|(font, result)| match result {
128 Ok(font_id) if *font_id == id => Some(font.clone()),
129 _ => None,
130 })
131 .next()
132 }
133
134 /// Resolves the specified font, falling back to the default font stack if
135 /// the font fails to load.
136 ///
137 /// # Panics
138 ///
139 /// Panics if the font and none of the fallbacks can be resolved.
140 pub fn resolve_font(&self, font: &Font) -> FontId {
141 if let Ok(font_id) = self.font_id(font) {
142 return font_id;
143 }
144 for fallback in &self.fallback_font_stack {
145 if let Ok(font_id) = self.font_id(fallback) {
146 return font_id;
147 }
148 }
149
150 panic!(
151 "failed to resolve font '{}' or any of the fallbacks: {}",
152 font.family,
153 self.fallback_font_stack
154 .iter()
155 .map(|fallback| &fallback.family)
156 .join(", ")
157 );
158 }
159
160 /// Get the bounding box for the given font and font size.
161 /// A font's bounding box is the smallest rectangle that could enclose all glyphs
162 /// in the font. superimposed over one another.
163 pub fn bounding_box(&self, font_id: FontId, font_size: Pixels) -> Bounds<Pixels> {
164 self.read_metrics(font_id, |metrics| metrics.bounding_box(font_size))
165 }
166
167 /// Get the typographic bounds for the given character, in the given font and size.
168 pub fn typographic_bounds(
169 &self,
170 font_id: FontId,
171 font_size: Pixels,
172 character: char,
173 ) -> Result<Bounds<Pixels>> {
174 let glyph_id = self
175 .platform_text_system
176 .glyph_for_char(font_id, character)
177 .with_context(|| format!("glyph not found for character '{character}'"))?;
178 let bounds = self
179 .platform_text_system
180 .typographic_bounds(font_id, glyph_id)?;
181 Ok(self.read_metrics(font_id, |metrics| {
182 (bounds / metrics.units_per_em as f32 * font_size.0).map(px)
183 }))
184 }
185
186 /// Get the advance width for the given character, in the given font and size.
187 pub fn advance(&self, font_id: FontId, font_size: Pixels, ch: char) -> Result<Size<Pixels>> {
188 let glyph_id = self
189 .platform_text_system
190 .glyph_for_char(font_id, ch)
191 .with_context(|| format!("glyph not found for character '{ch}'"))?;
192 let result = self.platform_text_system.advance(font_id, glyph_id)?
193 / self.units_per_em(font_id) as f32;
194
195 Ok(result * font_size)
196 }
197
198 /// Returns the width of an `em`.
199 ///
200 /// Uses the width of the `m` character in the given font and size.
201 pub fn em_width(&self, font_id: FontId, font_size: Pixels) -> Result<Pixels> {
202 Ok(self.typographic_bounds(font_id, font_size, 'm')?.size.width)
203 }
204
205 /// Returns the advance width of an `em`.
206 ///
207 /// Uses the advance width of the `m` character in the given font and size.
208 pub fn em_advance(&self, font_id: FontId, font_size: Pixels) -> Result<Pixels> {
209 Ok(self.advance(font_id, font_size, 'm')?.width)
210 }
211
212 /// Get the number of font size units per 'em square',
213 /// Per MDN: "an abstract square whose height is the intended distance between
214 /// lines of type in the same type size"
215 pub fn units_per_em(&self, font_id: FontId) -> u32 {
216 self.read_metrics(font_id, |metrics| metrics.units_per_em)
217 }
218
219 /// Get the height of a capital letter in the given font and size.
220 pub fn cap_height(&self, font_id: FontId, font_size: Pixels) -> Pixels {
221 self.read_metrics(font_id, |metrics| metrics.cap_height(font_size))
222 }
223
224 /// Get the height of the x character in the given font and size.
225 pub fn x_height(&self, font_id: FontId, font_size: Pixels) -> Pixels {
226 self.read_metrics(font_id, |metrics| metrics.x_height(font_size))
227 }
228
229 /// Get the recommended distance from the baseline for the given font
230 pub fn ascent(&self, font_id: FontId, font_size: Pixels) -> Pixels {
231 self.read_metrics(font_id, |metrics| metrics.ascent(font_size))
232 }
233
234 /// Get the recommended distance below the baseline for the given font,
235 /// in single spaced text.
236 pub fn descent(&self, font_id: FontId, font_size: Pixels) -> Pixels {
237 self.read_metrics(font_id, |metrics| metrics.descent(font_size))
238 }
239
240 /// Get the recommended baseline offset for the given font and line height.
241 pub fn baseline_offset(
242 &self,
243 font_id: FontId,
244 font_size: Pixels,
245 line_height: Pixels,
246 ) -> Pixels {
247 let ascent = self.ascent(font_id, font_size);
248 let descent = self.descent(font_id, font_size);
249 let padding_top = (line_height - ascent - descent) / 2.;
250 padding_top + ascent
251 }
252
253 fn read_metrics<T>(&self, font_id: FontId, read: impl FnOnce(&FontMetrics) -> T) -> T {
254 let lock = self.font_metrics.upgradable_read();
255
256 if let Some(metrics) = lock.get(&font_id) {
257 read(metrics)
258 } else {
259 let mut lock = RwLockUpgradableReadGuard::upgrade(lock);
260 let metrics = lock
261 .entry(font_id)
262 .or_insert_with(|| self.platform_text_system.font_metrics(font_id));
263 read(metrics)
264 }
265 }
266
267 /// Returns a handle to a line wrapper, for the given font and font size.
268 pub fn line_wrapper(self: &Arc<Self>, font: Font, font_size: Pixels) -> LineWrapperHandle {
269 let lock = &mut self.wrapper_pool.lock();
270 let font_id = self.resolve_font(&font);
271 let wrappers = lock
272 .entry(FontIdWithSize { font_id, font_size })
273 .or_default();
274 let wrapper = wrappers.pop().unwrap_or_else(|| {
275 LineWrapper::new(font_id, font_size, self.platform_text_system.clone())
276 });
277
278 LineWrapperHandle {
279 wrapper: Some(wrapper),
280 text_system: self.clone(),
281 }
282 }
283
284 /// Get the rasterized size and location of a specific, rendered glyph.
285 pub(crate) fn raster_bounds(&self, params: &RenderGlyphParams) -> Result<Bounds<DevicePixels>> {
286 let raster_bounds = self.raster_bounds.upgradable_read();
287 if let Some(bounds) = raster_bounds.get(params) {
288 Ok(*bounds)
289 } else {
290 let mut raster_bounds = RwLockUpgradableReadGuard::upgrade(raster_bounds);
291 let bounds = self.platform_text_system.glyph_raster_bounds(params)?;
292 raster_bounds.insert(params.clone(), bounds);
293 Ok(bounds)
294 }
295 }
296
297 pub(crate) fn rasterize_glyph(
298 &self,
299 params: &RenderGlyphParams,
300 ) -> Result<(Size<DevicePixels>, Vec<u8>)> {
301 let raster_bounds = self.raster_bounds(params)?;
302 self.platform_text_system
303 .rasterize_glyph(params, raster_bounds)
304 }
305}
306
307/// The GPUI text layout subsystem.
308#[derive(Deref)]
309pub struct WindowTextSystem {
310 line_layout_cache: LineLayoutCache,
311 #[deref]
312 text_system: Arc<TextSystem>,
313}
314
315impl WindowTextSystem {
316 pub(crate) fn new(text_system: Arc<TextSystem>) -> Self {
317 Self {
318 line_layout_cache: LineLayoutCache::new(text_system.platform_text_system.clone()),
319 text_system,
320 }
321 }
322
323 pub(crate) fn layout_index(&self) -> LineLayoutIndex {
324 self.line_layout_cache.layout_index()
325 }
326
327 pub(crate) fn reuse_layouts(&self, index: Range<LineLayoutIndex>) {
328 self.line_layout_cache.reuse_layouts(index)
329 }
330
331 pub(crate) fn truncate_layouts(&self, index: LineLayoutIndex) {
332 self.line_layout_cache.truncate_layouts(index)
333 }
334
335 /// Shape the given line, at the given font_size, for painting to the screen.
336 /// Subsets of the line can be styled independently with the `runs` parameter.
337 ///
338 /// Note that this method can only shape a single line of text. It will panic
339 /// if the text contains newlines. If you need to shape multiple lines of text,
340 /// use `TextLayout::shape_text` instead.
341 pub fn shape_line(
342 &self,
343 text: SharedString,
344 font_size: Pixels,
345 runs: &[TextRun],
346 ) -> ShapedLine {
347 debug_assert!(
348 text.find('\n').is_none(),
349 "text argument should not contain newlines"
350 );
351
352 let mut decoration_runs = SmallVec::<[DecorationRun; 32]>::new();
353 for run in runs {
354 if let Some(last_run) = decoration_runs.last_mut() {
355 if last_run.color == run.color
356 && last_run.underline == run.underline
357 && last_run.strikethrough == run.strikethrough
358 && last_run.background_color == run.background_color
359 {
360 last_run.len += run.len as u32;
361 continue;
362 }
363 }
364 decoration_runs.push(DecorationRun {
365 len: run.len as u32,
366 color: run.color,
367 background_color: run.background_color,
368 underline: run.underline,
369 strikethrough: run.strikethrough,
370 });
371 }
372
373 let layout = self.layout_line(&text, font_size, runs);
374
375 ShapedLine {
376 layout,
377 text,
378 decoration_runs,
379 }
380 }
381
382 /// Shape a multi line string of text, at the given font_size, for painting to the screen.
383 /// Subsets of the text can be styled independently with the `runs` parameter.
384 /// If `wrap_width` is provided, the line breaks will be adjusted to fit within the given width.
385 pub fn shape_text(
386 &self,
387 text: SharedString,
388 font_size: Pixels,
389 runs: &[TextRun],
390 wrap_width: Option<Pixels>,
391 line_clamp: Option<usize>,
392 ) -> Result<SmallVec<[WrappedLine; 1]>> {
393 let mut runs = runs.iter().filter(|run| run.len > 0).cloned().peekable();
394 let mut font_runs = self.font_runs_pool.lock().pop().unwrap_or_default();
395
396 let mut lines = SmallVec::new();
397 let mut line_start = 0;
398 let mut max_wrap_lines = line_clamp.unwrap_or(usize::MAX);
399 let mut wrapped_lines = 0;
400
401 let mut process_line = |line_text: SharedString| {
402 let line_end = line_start + line_text.len();
403
404 let mut last_font: Option<Font> = None;
405 let mut decoration_runs = SmallVec::<[DecorationRun; 32]>::new();
406 let mut run_start = line_start;
407 while run_start < line_end {
408 let Some(run) = runs.peek_mut() else {
409 break;
410 };
411
412 let run_len_within_line = cmp::min(line_end, run_start + run.len) - run_start;
413
414 if last_font == Some(run.font.clone()) {
415 font_runs.last_mut().unwrap().len += run_len_within_line;
416 } else {
417 last_font = Some(run.font.clone());
418 font_runs.push(FontRun {
419 len: run_len_within_line,
420 font_id: self.resolve_font(&run.font),
421 });
422 }
423
424 if decoration_runs.last().map_or(false, |last_run| {
425 last_run.color == run.color
426 && last_run.underline == run.underline
427 && last_run.strikethrough == run.strikethrough
428 && last_run.background_color == run.background_color
429 }) {
430 decoration_runs.last_mut().unwrap().len += run_len_within_line as u32;
431 } else {
432 decoration_runs.push(DecorationRun {
433 len: run_len_within_line as u32,
434 color: run.color,
435 background_color: run.background_color,
436 underline: run.underline,
437 strikethrough: run.strikethrough,
438 });
439 }
440
441 if run_len_within_line == run.len {
442 runs.next();
443 } else {
444 // Preserve the remainder of the run for the next line
445 run.len -= run_len_within_line;
446 }
447 run_start += run_len_within_line;
448 }
449
450 let layout = self.line_layout_cache.layout_wrapped_line(
451 &line_text,
452 font_size,
453 &font_runs,
454 wrap_width,
455 Some(max_wrap_lines - wrapped_lines),
456 );
457 wrapped_lines += layout.wrap_boundaries.len();
458
459 lines.push(WrappedLine {
460 layout,
461 decoration_runs,
462 text: line_text,
463 });
464
465 // Skip `\n` character.
466 line_start = line_end + 1;
467 if let Some(run) = runs.peek_mut() {
468 run.len -= 1;
469 if run.len == 0 {
470 runs.next();
471 }
472 }
473
474 font_runs.clear();
475 };
476
477 let mut split_lines = text.split('\n');
478 let mut processed = false;
479
480 if let Some(first_line) = split_lines.next() {
481 if let Some(second_line) = split_lines.next() {
482 processed = true;
483 process_line(first_line.to_string().into());
484 process_line(second_line.to_string().into());
485 for line_text in split_lines {
486 process_line(line_text.to_string().into());
487 }
488 }
489 }
490
491 if !processed {
492 process_line(text);
493 }
494
495 self.font_runs_pool.lock().push(font_runs);
496
497 Ok(lines)
498 }
499
500 pub(crate) fn finish_frame(&self) {
501 self.line_layout_cache.finish_frame()
502 }
503
504 /// Layout the given line of text, at the given font_size.
505 /// Subsets of the line can be styled independently with the `runs` parameter.
506 /// Generally, you should prefer to use `TextLayout::shape_line` instead, which
507 /// can be painted directly.
508 pub fn layout_line<Text>(
509 &self,
510 text: Text,
511 font_size: Pixels,
512 runs: &[TextRun],
513 ) -> Arc<LineLayout>
514 where
515 Text: AsRef<str>,
516 SharedString: From<Text>,
517 {
518 let mut font_runs = self.font_runs_pool.lock().pop().unwrap_or_default();
519 for run in runs.iter() {
520 let font_id = self.resolve_font(&run.font);
521 if let Some(last_run) = font_runs.last_mut() {
522 if last_run.font_id == font_id {
523 last_run.len += run.len;
524 continue;
525 }
526 }
527 font_runs.push(FontRun {
528 len: run.len,
529 font_id,
530 });
531 }
532
533 let layout = self
534 .line_layout_cache
535 .layout_line(text, font_size, &font_runs);
536
537 font_runs.clear();
538 self.font_runs_pool.lock().push(font_runs);
539
540 layout
541 }
542}
543
544#[derive(Hash, Eq, PartialEq)]
545struct FontIdWithSize {
546 font_id: FontId,
547 font_size: Pixels,
548}
549
550/// A handle into the text system, which can be used to compute the wrapped layout of text
551pub struct LineWrapperHandle {
552 wrapper: Option<LineWrapper>,
553 text_system: Arc<TextSystem>,
554}
555
556impl Drop for LineWrapperHandle {
557 fn drop(&mut self) {
558 let mut state = self.text_system.wrapper_pool.lock();
559 let wrapper = self.wrapper.take().unwrap();
560 state
561 .get_mut(&FontIdWithSize {
562 font_id: wrapper.font_id,
563 font_size: wrapper.font_size,
564 })
565 .unwrap()
566 .push(wrapper);
567 }
568}
569
570impl Deref for LineWrapperHandle {
571 type Target = LineWrapper;
572
573 fn deref(&self) -> &Self::Target {
574 self.wrapper.as_ref().unwrap()
575 }
576}
577
578impl DerefMut for LineWrapperHandle {
579 fn deref_mut(&mut self) -> &mut Self::Target {
580 self.wrapper.as_mut().unwrap()
581 }
582}
583
584/// The degree of blackness or stroke thickness of a font. This value ranges from 100.0 to 900.0,
585/// with 400.0 as normal.
586#[derive(Clone, Copy, Debug, PartialEq, PartialOrd, Serialize, Deserialize, JsonSchema)]
587pub struct FontWeight(pub f32);
588
589impl Default for FontWeight {
590 #[inline]
591 fn default() -> FontWeight {
592 FontWeight::NORMAL
593 }
594}
595
596impl Hash for FontWeight {
597 fn hash<H: Hasher>(&self, state: &mut H) {
598 state.write_u32(u32::from_be_bytes(self.0.to_be_bytes()));
599 }
600}
601
602impl Eq for FontWeight {}
603
604impl FontWeight {
605 /// Thin weight (100), the thinnest value.
606 pub const THIN: FontWeight = FontWeight(100.0);
607 /// Extra light weight (200).
608 pub const EXTRA_LIGHT: FontWeight = FontWeight(200.0);
609 /// Light weight (300).
610 pub const LIGHT: FontWeight = FontWeight(300.0);
611 /// Normal (400).
612 pub const NORMAL: FontWeight = FontWeight(400.0);
613 /// Medium weight (500, higher than normal).
614 pub const MEDIUM: FontWeight = FontWeight(500.0);
615 /// Semibold weight (600).
616 pub const SEMIBOLD: FontWeight = FontWeight(600.0);
617 /// Bold weight (700).
618 pub const BOLD: FontWeight = FontWeight(700.0);
619 /// Extra-bold weight (800).
620 pub const EXTRA_BOLD: FontWeight = FontWeight(800.0);
621 /// Black weight (900), the thickest value.
622 pub const BLACK: FontWeight = FontWeight(900.0);
623
624 /// All of the font weights, in order from thinnest to thickest.
625 pub const ALL: [FontWeight; 9] = [
626 Self::THIN,
627 Self::EXTRA_LIGHT,
628 Self::LIGHT,
629 Self::NORMAL,
630 Self::MEDIUM,
631 Self::SEMIBOLD,
632 Self::BOLD,
633 Self::EXTRA_BOLD,
634 Self::BLACK,
635 ];
636}
637
638/// Allows italic or oblique faces to be selected.
639#[derive(Clone, Copy, Eq, PartialEq, Debug, Hash, Default, Serialize, Deserialize, JsonSchema)]
640pub enum FontStyle {
641 /// A face that is neither italic not obliqued.
642 #[default]
643 Normal,
644 /// A form that is generally cursive in nature.
645 Italic,
646 /// A typically-sloped version of the regular face.
647 Oblique,
648}
649
650impl Display for FontStyle {
651 fn fmt(&self, f: &mut Formatter) -> fmt::Result {
652 Debug::fmt(self, f)
653 }
654}
655
656/// A styled run of text, for use in [`TextLayout`].
657#[derive(Clone, Debug, PartialEq, Eq)]
658pub struct TextRun {
659 /// A number of utf8 bytes
660 pub len: usize,
661 /// The font to use for this run.
662 pub font: Font,
663 /// The color
664 pub color: Hsla,
665 /// The background color (if any)
666 pub background_color: Option<Hsla>,
667 /// The underline style (if any)
668 pub underline: Option<UnderlineStyle>,
669 /// The strikethrough style (if any)
670 pub strikethrough: Option<StrikethroughStyle>,
671}
672
673#[cfg(all(target_os = "macos", test))]
674impl TextRun {
675 fn with_len(&self, len: usize) -> Self {
676 let mut this = self.clone();
677 this.len = len;
678 this
679 }
680}
681
682/// An identifier for a specific glyph, as returned by [`TextSystem::layout_line`].
683#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
684#[repr(C)]
685pub struct GlyphId(pub(crate) u32);
686
687#[derive(Clone, Debug, PartialEq)]
688pub(crate) struct RenderGlyphParams {
689 pub(crate) font_id: FontId,
690 pub(crate) glyph_id: GlyphId,
691 pub(crate) font_size: Pixels,
692 pub(crate) subpixel_variant: Point<u8>,
693 pub(crate) scale_factor: f32,
694 pub(crate) is_emoji: bool,
695}
696
697impl Eq for RenderGlyphParams {}
698
699impl Hash for RenderGlyphParams {
700 fn hash<H: Hasher>(&self, state: &mut H) {
701 self.font_id.0.hash(state);
702 self.glyph_id.0.hash(state);
703 self.font_size.0.to_bits().hash(state);
704 self.subpixel_variant.hash(state);
705 self.scale_factor.to_bits().hash(state);
706 self.is_emoji.hash(state);
707 }
708}
709
710/// The configuration details for identifying a specific font.
711#[derive(Clone, Debug, Eq, PartialEq, Hash)]
712pub struct Font {
713 /// The font family name.
714 ///
715 /// The special name ".SystemUIFont" is used to identify the system UI font, which varies based on platform.
716 pub family: SharedString,
717
718 /// The font features to use.
719 pub features: FontFeatures,
720
721 /// The fallbacks fonts to use.
722 pub fallbacks: Option<FontFallbacks>,
723
724 /// The font weight.
725 pub weight: FontWeight,
726
727 /// The font style.
728 pub style: FontStyle,
729}
730
731/// Get a [`Font`] for a given name.
732pub fn font(family: impl Into<SharedString>) -> Font {
733 Font {
734 family: family.into(),
735 features: FontFeatures::default(),
736 weight: FontWeight::default(),
737 style: FontStyle::default(),
738 fallbacks: None,
739 }
740}
741
742impl Font {
743 /// Set this Font to be bold
744 pub fn bold(mut self) -> Self {
745 self.weight = FontWeight::BOLD;
746 self
747 }
748
749 /// Set this Font to be italic
750 pub fn italic(mut self) -> Self {
751 self.style = FontStyle::Italic;
752 self
753 }
754}
755
756/// A struct for storing font metrics.
757/// It is used to define the measurements of a typeface.
758#[derive(Clone, Copy, Debug)]
759pub struct FontMetrics {
760 /// The number of font units that make up the "em square",
761 /// a scalable grid for determining the size of a typeface.
762 pub(crate) units_per_em: u32,
763
764 /// The vertical distance from the baseline of the font to the top of the glyph covers.
765 pub(crate) ascent: f32,
766
767 /// The vertical distance from the baseline of the font to the bottom of the glyph covers.
768 pub(crate) descent: f32,
769
770 /// The recommended additional space to add between lines of type.
771 pub(crate) line_gap: f32,
772
773 /// The suggested position of the underline.
774 pub(crate) underline_position: f32,
775
776 /// The suggested thickness of the underline.
777 pub(crate) underline_thickness: f32,
778
779 /// The height of a capital letter measured from the baseline of the font.
780 pub(crate) cap_height: f32,
781
782 /// The height of a lowercase x.
783 pub(crate) x_height: f32,
784
785 /// The outer limits of the area that the font covers.
786 /// Corresponds to the xMin / xMax / yMin / yMax values in the OpenType `head` table
787 pub(crate) bounding_box: Bounds<f32>,
788}
789
790impl FontMetrics {
791 /// Returns the vertical distance from the baseline of the font to the top of the glyph covers in pixels.
792 pub fn ascent(&self, font_size: Pixels) -> Pixels {
793 Pixels((self.ascent / self.units_per_em as f32) * font_size.0)
794 }
795
796 /// Returns the vertical distance from the baseline of the font to the bottom of the glyph covers in pixels.
797 pub fn descent(&self, font_size: Pixels) -> Pixels {
798 Pixels((self.descent / self.units_per_em as f32) * font_size.0)
799 }
800
801 /// Returns the recommended additional space to add between lines of type in pixels.
802 pub fn line_gap(&self, font_size: Pixels) -> Pixels {
803 Pixels((self.line_gap / self.units_per_em as f32) * font_size.0)
804 }
805
806 /// Returns the suggested position of the underline in pixels.
807 pub fn underline_position(&self, font_size: Pixels) -> Pixels {
808 Pixels((self.underline_position / self.units_per_em as f32) * font_size.0)
809 }
810
811 /// Returns the suggested thickness of the underline in pixels.
812 pub fn underline_thickness(&self, font_size: Pixels) -> Pixels {
813 Pixels((self.underline_thickness / self.units_per_em as f32) * font_size.0)
814 }
815
816 /// Returns the height of a capital letter measured from the baseline of the font in pixels.
817 pub fn cap_height(&self, font_size: Pixels) -> Pixels {
818 Pixels((self.cap_height / self.units_per_em as f32) * font_size.0)
819 }
820
821 /// Returns the height of a lowercase x in pixels.
822 pub fn x_height(&self, font_size: Pixels) -> Pixels {
823 Pixels((self.x_height / self.units_per_em as f32) * font_size.0)
824 }
825
826 /// Returns the outer limits of the area that the font covers in pixels.
827 pub fn bounding_box(&self, font_size: Pixels) -> Bounds<Pixels> {
828 (self.bounding_box / self.units_per_em as f32 * font_size.0).map(px)
829 }
830}