1use crate::{
2 point, px, size, Bounds, DevicePixels, Font, FontFallbacks, FontFeatures, FontId, FontMetrics,
3 FontRun, FontStyle, FontWeight, GlyphId, LineLayout, Pixels, PlatformTextSystem, Point,
4 RenderGlyphParams, Result, ShapedGlyph, ShapedRun, SharedString, Size, SUBPIXEL_VARIANTS,
5};
6use anyhow::anyhow;
7use cocoa::appkit::{CGFloat, CGPoint};
8use collections::HashMap;
9use core_foundation::{
10 attributed_string::CFMutableAttributedString,
11 base::{CFRange, TCFType},
12 number::CFNumber,
13 string::CFString,
14};
15use core_graphics::{
16 base::{kCGImageAlphaPremultipliedLast, CGGlyph},
17 color_space::CGColorSpace,
18 context::CGContext,
19};
20use core_text::{
21 font::CTFont,
22 font_descriptor::{
23 kCTFontSlantTrait, kCTFontSymbolicTrait, kCTFontWeightTrait, kCTFontWidthTrait,
24 },
25 line::CTLine,
26 string_attributes::kCTFontAttributeName,
27};
28use font_kit::{
29 font::Font as FontKitFont,
30 handle::Handle,
31 hinting::HintingOptions,
32 metrics::Metrics,
33 properties::{Style as FontkitStyle, Weight as FontkitWeight},
34 source::SystemSource,
35 sources::mem::MemSource,
36};
37use parking_lot::{RwLock, RwLockUpgradableReadGuard};
38use pathfinder_geometry::{
39 rect::{RectF, RectI},
40 transform2d::Transform2F,
41 vector::{Vector2F, Vector2I},
42};
43use smallvec::SmallVec;
44use std::{borrow::Cow, char, cmp, convert::TryFrom, sync::Arc};
45
46use super::open_type::apply_features_and_fallbacks;
47
48#[allow(non_upper_case_globals)]
49const kCGImageAlphaOnly: u32 = 7;
50
51pub(crate) struct MacTextSystem(RwLock<MacTextSystemState>);
52
53#[derive(Clone, PartialEq, Eq, Hash)]
54struct FontKey {
55 font_family: SharedString,
56 font_features: FontFeatures,
57 font_fallbacks: Option<FontFallbacks>,
58}
59
60struct MacTextSystemState {
61 memory_source: MemSource,
62 system_source: SystemSource,
63 fonts: Vec<FontKitFont>,
64 font_selections: HashMap<Font, FontId>,
65 font_ids_by_postscript_name: HashMap<String, FontId>,
66 font_ids_by_font_key: HashMap<FontKey, SmallVec<[FontId; 4]>>,
67 postscript_names_by_font_id: HashMap<FontId, String>,
68}
69
70impl MacTextSystem {
71 pub(crate) fn new() -> Self {
72 Self(RwLock::new(MacTextSystemState {
73 memory_source: MemSource::empty(),
74 system_source: SystemSource::new(),
75 fonts: Vec::new(),
76 font_selections: HashMap::default(),
77 font_ids_by_postscript_name: HashMap::default(),
78 font_ids_by_font_key: HashMap::default(),
79 postscript_names_by_font_id: HashMap::default(),
80 }))
81 }
82}
83
84impl Default for MacTextSystem {
85 fn default() -> Self {
86 Self::new()
87 }
88}
89
90impl PlatformTextSystem for MacTextSystem {
91 fn add_fonts(&self, fonts: Vec<Cow<'static, [u8]>>) -> Result<()> {
92 self.0.write().add_fonts(fonts)
93 }
94
95 fn all_font_names(&self) -> Vec<String> {
96 let mut names = Vec::new();
97 let collection = core_text::font_collection::create_for_all_families();
98 let Some(descriptors) = collection.get_descriptors() else {
99 return names;
100 };
101 for descriptor in descriptors.into_iter() {
102 names.extend(lenient_font_attributes::family_name(&descriptor));
103 }
104 if let Ok(fonts_in_memory) = self.0.read().memory_source.all_families() {
105 names.extend(fonts_in_memory);
106 }
107 names
108 }
109
110 fn font_id(&self, font: &Font) -> Result<FontId> {
111 let lock = self.0.upgradable_read();
112 if let Some(font_id) = lock.font_selections.get(font) {
113 Ok(*font_id)
114 } else {
115 let mut lock = RwLockUpgradableReadGuard::upgrade(lock);
116 let font_key = FontKey {
117 font_family: font.family.clone(),
118 font_features: font.features.clone(),
119 font_fallbacks: font.fallbacks.clone(),
120 };
121 let candidates = if let Some(font_ids) = lock.font_ids_by_font_key.get(&font_key) {
122 font_ids.as_slice()
123 } else {
124 let font_ids =
125 lock.load_family(&font.family, &font.features, font.fallbacks.as_ref())?;
126 lock.font_ids_by_font_key.insert(font_key.clone(), font_ids);
127 lock.font_ids_by_font_key[&font_key].as_ref()
128 };
129
130 let candidate_properties = candidates
131 .iter()
132 .map(|font_id| lock.fonts[font_id.0].properties())
133 .collect::<SmallVec<[_; 4]>>();
134
135 let ix = font_kit::matching::find_best_match(
136 &candidate_properties,
137 &font_kit::properties::Properties {
138 style: font.style.into(),
139 weight: font.weight.into(),
140 stretch: Default::default(),
141 },
142 )?;
143
144 let font_id = candidates[ix];
145 lock.font_selections.insert(font.clone(), font_id);
146 Ok(font_id)
147 }
148 }
149
150 fn font_metrics(&self, font_id: FontId) -> FontMetrics {
151 self.0.read().fonts[font_id.0].metrics().into()
152 }
153
154 fn typographic_bounds(&self, font_id: FontId, glyph_id: GlyphId) -> Result<Bounds<f32>> {
155 Ok(self.0.read().fonts[font_id.0]
156 .typographic_bounds(glyph_id.0)?
157 .into())
158 }
159
160 fn advance(&self, font_id: FontId, glyph_id: GlyphId) -> Result<Size<f32>> {
161 self.0.read().advance(font_id, glyph_id)
162 }
163
164 fn glyph_for_char(&self, font_id: FontId, ch: char) -> Option<GlyphId> {
165 self.0.read().glyph_for_char(font_id, ch)
166 }
167
168 fn glyph_raster_bounds(&self, params: &RenderGlyphParams) -> Result<Bounds<DevicePixels>> {
169 self.0.read().raster_bounds(params)
170 }
171
172 fn rasterize_glyph(
173 &self,
174 glyph_id: &RenderGlyphParams,
175 raster_bounds: Bounds<DevicePixels>,
176 ) -> Result<(Size<DevicePixels>, Vec<u8>)> {
177 self.0.read().rasterize_glyph(glyph_id, raster_bounds)
178 }
179
180 fn layout_line(&self, text: &str, font_size: Pixels, font_runs: &[FontRun]) -> LineLayout {
181 self.0.write().layout_line(text, font_size, font_runs)
182 }
183}
184
185impl MacTextSystemState {
186 fn add_fonts(&mut self, fonts: Vec<Cow<'static, [u8]>>) -> Result<()> {
187 let fonts = fonts
188 .into_iter()
189 .map(|bytes| match bytes {
190 Cow::Borrowed(embedded_font) => {
191 let data_provider = unsafe {
192 core_graphics::data_provider::CGDataProvider::from_slice(embedded_font)
193 };
194 let font = core_graphics::font::CGFont::from_data_provider(data_provider)
195 .map_err(|_| anyhow!("Could not load an embedded font."))?;
196 let font = font_kit::loaders::core_text::Font::from_core_graphics_font(font);
197 Ok(Handle::from_native(&font))
198 }
199 Cow::Owned(bytes) => Ok(Handle::from_memory(Arc::new(bytes), 0)),
200 })
201 .collect::<Result<Vec<_>>>()?;
202 self.memory_source.add_fonts(fonts.into_iter())?;
203 Ok(())
204 }
205
206 fn load_family(
207 &mut self,
208 name: &str,
209 features: &FontFeatures,
210 fallbacks: Option<&FontFallbacks>,
211 ) -> Result<SmallVec<[FontId; 4]>> {
212 let name = if name == ".SystemUIFont" {
213 ".AppleSystemUIFont"
214 } else {
215 name
216 };
217
218 let mut font_ids = SmallVec::new();
219 let family = self
220 .memory_source
221 .select_family_by_name(name)
222 .or_else(|_| self.system_source.select_family_by_name(name))?;
223 for font in family.fonts() {
224 let mut font = font.load()?;
225
226 apply_features_and_fallbacks(&mut font, features, fallbacks)?;
227 // This block contains a precautionary fix to guard against loading fonts
228 // that might cause panics due to `.unwrap()`s up the chain.
229 {
230 // We use the 'm' character for text measurements in various spots
231 // (e.g., the editor). However, at time of writing some of those usages
232 // will panic if the font has no 'm' glyph.
233 //
234 // Therefore, we check up front that the font has the necessary glyph.
235 let has_m_glyph = font.glyph_for_char('m').is_some();
236
237 // HACK: The 'Segoe Fluent Icons' font does not have an 'm' glyph,
238 // but we need to be able to load it for rendering Windows icons in
239 // the Storybook (on macOS).
240 let is_segoe_fluent_icons = font.full_name() == "Segoe Fluent Icons";
241
242 if !has_m_glyph && !is_segoe_fluent_icons {
243 // I spent far too long trying to track down why a font missing the 'm'
244 // character wasn't loading. This log statement will hopefully save
245 // someone else from suffering the same fate.
246 log::warn!(
247 "font '{}' has no 'm' character and was not loaded",
248 font.full_name()
249 );
250 continue;
251 }
252 }
253
254 // We've seen a number of panics in production caused by calling font.properties()
255 // which unwraps a downcast to CFNumber. This is an attempt to avoid the panic,
256 // and to try and identify the incalcitrant font.
257 let traits = font.native_font().all_traits();
258 if unsafe {
259 !(traits
260 .get(kCTFontSymbolicTrait)
261 .downcast::<CFNumber>()
262 .is_some()
263 && traits
264 .get(kCTFontWidthTrait)
265 .downcast::<CFNumber>()
266 .is_some()
267 && traits
268 .get(kCTFontWeightTrait)
269 .downcast::<CFNumber>()
270 .is_some()
271 && traits
272 .get(kCTFontSlantTrait)
273 .downcast::<CFNumber>()
274 .is_some())
275 } {
276 log::error!(
277 "Failed to read traits for font {:?}",
278 font.postscript_name().unwrap()
279 );
280 continue;
281 }
282
283 let font_id = FontId(self.fonts.len());
284 font_ids.push(font_id);
285 let postscript_name = font.postscript_name().unwrap();
286 self.font_ids_by_postscript_name
287 .insert(postscript_name.clone(), font_id);
288 self.postscript_names_by_font_id
289 .insert(font_id, postscript_name);
290 self.fonts.push(font);
291 }
292 Ok(font_ids)
293 }
294
295 fn advance(&self, font_id: FontId, glyph_id: GlyphId) -> Result<Size<f32>> {
296 Ok(self.fonts[font_id.0].advance(glyph_id.0)?.into())
297 }
298
299 fn glyph_for_char(&self, font_id: FontId, ch: char) -> Option<GlyphId> {
300 self.fonts[font_id.0].glyph_for_char(ch).map(GlyphId)
301 }
302
303 fn id_for_native_font(&mut self, requested_font: CTFont) -> FontId {
304 let postscript_name = requested_font.postscript_name();
305 if let Some(font_id) = self.font_ids_by_postscript_name.get(&postscript_name) {
306 *font_id
307 } else {
308 let font_id = FontId(self.fonts.len());
309 self.font_ids_by_postscript_name
310 .insert(postscript_name.clone(), font_id);
311 self.postscript_names_by_font_id
312 .insert(font_id, postscript_name);
313 self.fonts
314 .push(font_kit::font::Font::from_core_graphics_font(
315 requested_font.copy_to_CGFont(),
316 ));
317 font_id
318 }
319 }
320
321 fn is_emoji(&self, font_id: FontId) -> bool {
322 self.postscript_names_by_font_id
323 .get(&font_id)
324 .map_or(false, |postscript_name| {
325 postscript_name == "AppleColorEmoji" || postscript_name == ".AppleColorEmojiUI"
326 })
327 }
328
329 fn raster_bounds(&self, params: &RenderGlyphParams) -> Result<Bounds<DevicePixels>> {
330 let font = &self.fonts[params.font_id.0];
331 let scale = Transform2F::from_scale(params.scale_factor);
332 Ok(font
333 .raster_bounds(
334 params.glyph_id.0,
335 params.font_size.into(),
336 scale,
337 HintingOptions::None,
338 font_kit::canvas::RasterizationOptions::GrayscaleAa,
339 )?
340 .into())
341 }
342
343 fn rasterize_glyph(
344 &self,
345 params: &RenderGlyphParams,
346 glyph_bounds: Bounds<DevicePixels>,
347 ) -> Result<(Size<DevicePixels>, Vec<u8>)> {
348 if glyph_bounds.size.width.0 == 0 || glyph_bounds.size.height.0 == 0 {
349 Err(anyhow!("glyph bounds are empty"))
350 } else {
351 // Add an extra pixel when the subpixel variant isn't zero to make room for anti-aliasing.
352 let mut bitmap_size = glyph_bounds.size;
353 if params.subpixel_variant.x > 0 {
354 bitmap_size.width += DevicePixels(1);
355 }
356 if params.subpixel_variant.y > 0 {
357 bitmap_size.height += DevicePixels(1);
358 }
359 let bitmap_size = bitmap_size;
360
361 let mut bytes;
362 let cx;
363 if params.is_emoji {
364 bytes = vec![0; bitmap_size.width.0 as usize * 4 * bitmap_size.height.0 as usize];
365 cx = CGContext::create_bitmap_context(
366 Some(bytes.as_mut_ptr() as *mut _),
367 bitmap_size.width.0 as usize,
368 bitmap_size.height.0 as usize,
369 8,
370 bitmap_size.width.0 as usize * 4,
371 &CGColorSpace::create_device_rgb(),
372 kCGImageAlphaPremultipliedLast,
373 );
374 } else {
375 bytes = vec![0; bitmap_size.width.0 as usize * bitmap_size.height.0 as usize];
376 cx = CGContext::create_bitmap_context(
377 Some(bytes.as_mut_ptr() as *mut _),
378 bitmap_size.width.0 as usize,
379 bitmap_size.height.0 as usize,
380 8,
381 bitmap_size.width.0 as usize,
382 &CGColorSpace::create_device_gray(),
383 kCGImageAlphaOnly,
384 );
385 }
386
387 // Move the origin to bottom left and account for scaling, this
388 // makes drawing text consistent with the font-kit's raster_bounds.
389 cx.translate(
390 -glyph_bounds.origin.x.0 as CGFloat,
391 (glyph_bounds.origin.y.0 + glyph_bounds.size.height.0) as CGFloat,
392 );
393 cx.scale(
394 params.scale_factor as CGFloat,
395 params.scale_factor as CGFloat,
396 );
397
398 let subpixel_shift = params
399 .subpixel_variant
400 .map(|v| v as f32 / SUBPIXEL_VARIANTS as f32);
401 cx.set_allows_font_subpixel_positioning(true);
402 cx.set_should_subpixel_position_fonts(true);
403 cx.set_allows_font_subpixel_quantization(false);
404 cx.set_should_subpixel_quantize_fonts(false);
405 self.fonts[params.font_id.0]
406 .native_font()
407 .clone_with_font_size(f32::from(params.font_size) as CGFloat)
408 .draw_glyphs(
409 &[params.glyph_id.0 as CGGlyph],
410 &[CGPoint::new(
411 (subpixel_shift.x / params.scale_factor) as CGFloat,
412 (subpixel_shift.y / params.scale_factor) as CGFloat,
413 )],
414 cx,
415 );
416
417 if params.is_emoji {
418 // Convert from RGBA with premultiplied alpha to BGRA with straight alpha.
419 for pixel in bytes.chunks_exact_mut(4) {
420 pixel.swap(0, 2);
421 let a = pixel[3] as f32 / 255.;
422 pixel[0] = (pixel[0] as f32 / a) as u8;
423 pixel[1] = (pixel[1] as f32 / a) as u8;
424 pixel[2] = (pixel[2] as f32 / a) as u8;
425 }
426 }
427
428 Ok((bitmap_size, bytes))
429 }
430 }
431
432 fn layout_line(&mut self, text: &str, font_size: Pixels, font_runs: &[FontRun]) -> LineLayout {
433 // Construct the attributed string, converting UTF8 ranges to UTF16 ranges.
434 let mut string = CFMutableAttributedString::new();
435 {
436 string.replace_str(&CFString::new(text), CFRange::init(0, 0));
437 let utf16_line_len = string.char_len() as usize;
438
439 let mut ix_converter = StringIndexConverter::new(text);
440 for run in font_runs {
441 let utf8_end = ix_converter.utf8_ix + run.len;
442 let utf16_start = ix_converter.utf16_ix;
443
444 if utf16_start >= utf16_line_len {
445 break;
446 }
447
448 ix_converter.advance_to_utf8_ix(utf8_end);
449 let utf16_end = cmp::min(ix_converter.utf16_ix, utf16_line_len);
450
451 let cf_range =
452 CFRange::init(utf16_start as isize, (utf16_end - utf16_start) as isize);
453
454 let font: &FontKitFont = &self.fonts[run.font_id.0];
455
456 unsafe {
457 string.set_attribute(
458 cf_range,
459 kCTFontAttributeName,
460 &font.native_font().clone_with_font_size(font_size.into()),
461 );
462 }
463
464 if utf16_end == utf16_line_len {
465 break;
466 }
467 }
468 }
469
470 // Retrieve the glyphs from the shaped line, converting UTF16 offsets to UTF8 offsets.
471 let line = CTLine::new_with_attributed_string(string.as_concrete_TypeRef());
472
473 let mut runs = Vec::new();
474 for run in line.glyph_runs().into_iter() {
475 let attributes = run.attributes().unwrap();
476 let font = unsafe {
477 attributes
478 .get(kCTFontAttributeName)
479 .downcast::<CTFont>()
480 .unwrap()
481 };
482 let font_id = self.id_for_native_font(font);
483
484 let mut ix_converter = StringIndexConverter::new(text);
485 let mut glyphs = SmallVec::new();
486 for ((glyph_id, position), glyph_utf16_ix) in run
487 .glyphs()
488 .iter()
489 .zip(run.positions().iter())
490 .zip(run.string_indices().iter())
491 {
492 let glyph_utf16_ix = usize::try_from(*glyph_utf16_ix).unwrap();
493 ix_converter.advance_to_utf16_ix(glyph_utf16_ix);
494 glyphs.push(ShapedGlyph {
495 id: GlyphId(*glyph_id as u32),
496 position: point(position.x as f32, position.y as f32).map(px),
497 index: ix_converter.utf8_ix,
498 is_emoji: self.is_emoji(font_id),
499 });
500 }
501
502 runs.push(ShapedRun { font_id, glyphs })
503 }
504
505 let typographic_bounds = line.get_typographic_bounds();
506 LineLayout {
507 runs,
508 font_size,
509 width: typographic_bounds.width.into(),
510 ascent: typographic_bounds.ascent.into(),
511 descent: typographic_bounds.descent.into(),
512 len: text.len(),
513 }
514 }
515}
516
517#[derive(Clone)]
518struct StringIndexConverter<'a> {
519 text: &'a str,
520 utf8_ix: usize,
521 utf16_ix: usize,
522}
523
524impl<'a> StringIndexConverter<'a> {
525 fn new(text: &'a str) -> Self {
526 Self {
527 text,
528 utf8_ix: 0,
529 utf16_ix: 0,
530 }
531 }
532
533 fn advance_to_utf8_ix(&mut self, utf8_target: usize) {
534 for (ix, c) in self.text[self.utf8_ix..].char_indices() {
535 if self.utf8_ix + ix >= utf8_target {
536 self.utf8_ix += ix;
537 return;
538 }
539 self.utf16_ix += c.len_utf16();
540 }
541 self.utf8_ix = self.text.len();
542 }
543
544 fn advance_to_utf16_ix(&mut self, utf16_target: usize) {
545 for (ix, c) in self.text[self.utf8_ix..].char_indices() {
546 if self.utf16_ix >= utf16_target {
547 self.utf8_ix += ix;
548 return;
549 }
550 self.utf16_ix += c.len_utf16();
551 }
552 self.utf8_ix = self.text.len();
553 }
554}
555
556impl From<Metrics> for FontMetrics {
557 fn from(metrics: Metrics) -> Self {
558 FontMetrics {
559 units_per_em: metrics.units_per_em,
560 ascent: metrics.ascent,
561 descent: metrics.descent,
562 line_gap: metrics.line_gap,
563 underline_position: metrics.underline_position,
564 underline_thickness: metrics.underline_thickness,
565 cap_height: metrics.cap_height,
566 x_height: metrics.x_height,
567 bounding_box: metrics.bounding_box.into(),
568 }
569 }
570}
571
572impl From<RectF> for Bounds<f32> {
573 fn from(rect: RectF) -> Self {
574 Bounds {
575 origin: point(rect.origin_x(), rect.origin_y()),
576 size: size(rect.width(), rect.height()),
577 }
578 }
579}
580
581impl From<RectI> for Bounds<DevicePixels> {
582 fn from(rect: RectI) -> Self {
583 Bounds {
584 origin: point(DevicePixels(rect.origin_x()), DevicePixels(rect.origin_y())),
585 size: size(DevicePixels(rect.width()), DevicePixels(rect.height())),
586 }
587 }
588}
589
590impl From<Vector2I> for Size<DevicePixels> {
591 fn from(value: Vector2I) -> Self {
592 size(value.x().into(), value.y().into())
593 }
594}
595
596impl From<RectI> for Bounds<i32> {
597 fn from(rect: RectI) -> Self {
598 Bounds {
599 origin: point(rect.origin_x(), rect.origin_y()),
600 size: size(rect.width(), rect.height()),
601 }
602 }
603}
604
605impl From<Point<u32>> for Vector2I {
606 fn from(size: Point<u32>) -> Self {
607 Vector2I::new(size.x as i32, size.y as i32)
608 }
609}
610
611impl From<Vector2F> for Size<f32> {
612 fn from(vec: Vector2F) -> Self {
613 size(vec.x(), vec.y())
614 }
615}
616
617impl From<FontWeight> for FontkitWeight {
618 fn from(value: FontWeight) -> Self {
619 FontkitWeight(value.0)
620 }
621}
622
623impl From<FontStyle> for FontkitStyle {
624 fn from(style: FontStyle) -> Self {
625 match style {
626 FontStyle::Normal => FontkitStyle::Normal,
627 FontStyle::Italic => FontkitStyle::Italic,
628 FontStyle::Oblique => FontkitStyle::Oblique,
629 }
630 }
631}
632
633// Some fonts may have no attributes despite `core_text` requiring them (and panicking).
634// This is the same version as `core_text` has without `expect` calls.
635mod lenient_font_attributes {
636 use core_foundation::{
637 base::{CFRetain, CFType, TCFType},
638 string::{CFString, CFStringRef},
639 };
640 use core_text::font_descriptor::{
641 kCTFontFamilyNameAttribute, CTFontDescriptor, CTFontDescriptorCopyAttribute,
642 };
643
644 pub fn family_name(descriptor: &CTFontDescriptor) -> Option<String> {
645 unsafe { get_string_attribute(descriptor, kCTFontFamilyNameAttribute) }
646 }
647
648 fn get_string_attribute(
649 descriptor: &CTFontDescriptor,
650 attribute: CFStringRef,
651 ) -> Option<String> {
652 unsafe {
653 let value = CTFontDescriptorCopyAttribute(descriptor.as_concrete_TypeRef(), attribute);
654 if value.is_null() {
655 return None;
656 }
657
658 let value = CFType::wrap_under_create_rule(value);
659 assert!(value.instance_of::<CFString>());
660 let s = wrap_under_get_rule(value.as_CFTypeRef() as CFStringRef);
661 Some(s.to_string())
662 }
663 }
664
665 unsafe fn wrap_under_get_rule(reference: CFStringRef) -> CFString {
666 assert!(!reference.is_null(), "Attempted to create a NULL object.");
667 let reference = CFRetain(reference as *const ::std::os::raw::c_void) as CFStringRef;
668 TCFType::wrap_under_create_rule(reference)
669 }
670}
671
672#[cfg(test)]
673mod tests {
674 use crate::{font, px, FontRun, GlyphId, MacTextSystem, PlatformTextSystem};
675
676 #[test]
677 fn test_layout_line_bom_char() {
678 let fonts = MacTextSystem::new();
679 let font_id = fonts.font_id(&font("Helvetica")).unwrap();
680 let line = "\u{feff}";
681 let mut style = FontRun {
682 font_id,
683 len: line.len(),
684 };
685
686 let layout = fonts.layout_line(line, px(16.), &[style]);
687 assert_eq!(layout.len, line.len());
688 assert!(layout.runs.is_empty());
689
690 let line = "a\u{feff}b";
691 style.len = line.len();
692 let layout = fonts.layout_line(line, px(16.), &[style]);
693 assert_eq!(layout.len, line.len());
694 assert_eq!(layout.runs.len(), 1);
695 assert_eq!(layout.runs[0].glyphs.len(), 2);
696 assert_eq!(layout.runs[0].glyphs[0].id, GlyphId(68u32)); // a
697 // There's no glyph for \u{feff}
698 assert_eq!(layout.runs[0].glyphs[1].id, GlyphId(69u32)); // b
699 }
700}