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