text_system.rs

  1use crate::{
  2    point, px, size, Bounds, FontFeatures, FontId, FontMetrics, FontStyle, FontWeight, Glyph,
  3    GlyphId, LineLayout, Pixels, PlatformTextSystem, Point, RasterizationOptions, Run, RunStyle,
  4    Size,
  5};
  6use cocoa::appkit::{CGFloat, CGPoint};
  7use collections::HashMap;
  8use core_foundation::{
  9    array::CFIndex,
 10    attributed_string::{CFAttributedStringRef, CFMutableAttributedString},
 11    base::{CFRange, TCFType},
 12    string::CFString,
 13};
 14use core_graphics::{
 15    base::{kCGImageAlphaPremultipliedLast, CGGlyph},
 16    color_space::CGColorSpace,
 17    context::CGContext,
 18};
 19use core_text::{font::CTFont, line::CTLine, string_attributes::kCTFontAttributeName};
 20use font_kit::{
 21    handle::Handle,
 22    hinting::HintingOptions,
 23    metrics::Metrics,
 24    properties::{Style as FontkitStyle, Weight as FontkitWeight},
 25    source::SystemSource,
 26    sources::mem::MemSource,
 27};
 28use parking_lot::RwLock;
 29use pathfinder_geometry::{
 30    rect::{RectF, RectI},
 31    transform2d::Transform2F,
 32    vector::{Vector2F, Vector2I},
 33};
 34use std::{cell::RefCell, char, cmp, convert::TryFrom, ffi::c_void, sync::Arc};
 35
 36use super::open_type;
 37
 38#[allow(non_upper_case_globals)]
 39const kCGImageAlphaOnly: u32 = 7;
 40
 41pub struct MacTextSystem(RwLock<TextSystemState>);
 42
 43struct TextSystemState {
 44    memory_source: MemSource,
 45    system_source: SystemSource,
 46    fonts: Vec<font_kit::font::Font>,
 47    font_ids_by_postscript_name: HashMap<String, FontId>,
 48    postscript_names_by_font_id: HashMap<FontId, String>,
 49}
 50
 51impl MacTextSystem {
 52    pub fn new() -> Self {
 53        Self(RwLock::new(TextSystemState {
 54            memory_source: MemSource::empty(),
 55            system_source: SystemSource::new(),
 56            fonts: Vec::new(),
 57            font_ids_by_postscript_name: Default::default(),
 58            postscript_names_by_font_id: Default::default(),
 59        }))
 60    }
 61}
 62
 63impl Default for MacTextSystem {
 64    fn default() -> Self {
 65        Self::new()
 66    }
 67}
 68
 69impl PlatformTextSystem for MacTextSystem {
 70    fn add_fonts(&self, fonts: &[Arc<Vec<u8>>]) -> anyhow::Result<()> {
 71        self.0.write().add_fonts(fonts)
 72    }
 73
 74    fn all_families(&self) -> Vec<String> {
 75        self.0
 76            .read()
 77            .system_source
 78            .all_families()
 79            .expect("core text should never return an error")
 80    }
 81
 82    fn load_family(&self, name: &str, features: &FontFeatures) -> anyhow::Result<Vec<FontId>> {
 83        self.0.write().load_family(name, features)
 84    }
 85
 86    fn select_font(
 87        &self,
 88        font_ids: &[FontId],
 89        weight: FontWeight,
 90        style: FontStyle,
 91    ) -> anyhow::Result<FontId> {
 92        self.0.read().select_font(font_ids, weight, style)
 93    }
 94
 95    fn font_metrics(&self, font_id: FontId) -> FontMetrics {
 96        self.0.read().font_metrics(font_id)
 97    }
 98
 99    fn typographic_bounds(
100        &self,
101        font_id: FontId,
102        glyph_id: GlyphId,
103    ) -> anyhow::Result<Bounds<f32>> {
104        self.0.read().typographic_bounds(font_id, glyph_id)
105    }
106
107    fn advance(&self, font_id: FontId, glyph_id: GlyphId) -> anyhow::Result<Size<f32>> {
108        self.0.read().advance(font_id, glyph_id)
109    }
110
111    fn glyph_for_char(&self, font_id: FontId, ch: char) -> Option<GlyphId> {
112        self.0.read().glyph_for_char(font_id, ch)
113    }
114
115    fn rasterize_glyph(
116        &self,
117        font_id: FontId,
118        font_size: f32,
119        glyph_id: GlyphId,
120        subpixel_shift: Point<Pixels>,
121        scale_factor: f32,
122        options: RasterizationOptions,
123    ) -> Option<(Bounds<u32>, Vec<u8>)> {
124        self.0.read().rasterize_glyph(
125            font_id,
126            font_size,
127            glyph_id,
128            subpixel_shift,
129            scale_factor,
130            options,
131        )
132    }
133
134    fn layout_line(&self, text: &str, font_size: Pixels, runs: &[(usize, RunStyle)]) -> LineLayout {
135        self.0.write().layout_line(text, font_size, runs)
136    }
137
138    fn wrap_line(
139        &self,
140        text: &str,
141        font_id: FontId,
142        font_size: Pixels,
143        width: Pixels,
144    ) -> Vec<usize> {
145        self.0.read().wrap_line(text, font_id, font_size, width)
146    }
147}
148
149impl TextSystemState {
150    fn add_fonts(&mut self, fonts: &[Arc<Vec<u8>>]) -> anyhow::Result<()> {
151        self.memory_source.add_fonts(
152            fonts
153                .iter()
154                .map(|bytes| Handle::from_memory(bytes.clone(), 0)),
155        )?;
156        Ok(())
157    }
158
159    fn load_family(&mut self, name: &str, features: &FontFeatures) -> anyhow::Result<Vec<FontId>> {
160        let mut font_ids = Vec::new();
161
162        let family = self
163            .memory_source
164            .select_family_by_name(name)
165            .or_else(|_| self.system_source.select_family_by_name(name))?;
166        for font in family.fonts() {
167            let mut font = font.load()?;
168            open_type::apply_features(&mut font, features);
169            let font_id = FontId(self.fonts.len());
170            font_ids.push(font_id);
171            let postscript_name = font.postscript_name().unwrap();
172            self.font_ids_by_postscript_name
173                .insert(postscript_name.clone(), font_id);
174            self.postscript_names_by_font_id
175                .insert(font_id, postscript_name);
176            self.fonts.push(font);
177        }
178        Ok(font_ids)
179    }
180
181    fn select_font(
182        &self,
183        font_ids: &[FontId],
184        weight: FontWeight,
185        style: FontStyle,
186    ) -> anyhow::Result<FontId> {
187        let candidates = font_ids
188            .iter()
189            .map(|font_id| self.fonts[font_id.0].properties())
190            .collect::<Vec<_>>();
191        let idx = font_kit::matching::find_best_match(
192            &candidates,
193            &font_kit::properties::Properties {
194                style: style.into(),
195                weight: weight.into(),
196                stretch: Default::default(),
197            },
198        )?;
199        Ok(font_ids[idx])
200    }
201
202    fn font_metrics(&self, font_id: FontId) -> FontMetrics {
203        self.fonts[font_id.0].metrics().into()
204    }
205
206    fn typographic_bounds(
207        &self,
208        font_id: FontId,
209        glyph_id: GlyphId,
210    ) -> anyhow::Result<Bounds<f32>> {
211        Ok(self.fonts[font_id.0]
212            .typographic_bounds(glyph_id.into())?
213            .into())
214    }
215
216    fn advance(&self, font_id: FontId, glyph_id: GlyphId) -> anyhow::Result<Size<f32>> {
217        Ok(self.fonts[font_id.0].advance(glyph_id.into())?.into())
218    }
219
220    fn glyph_for_char(&self, font_id: FontId, ch: char) -> Option<GlyphId> {
221        self.fonts[font_id.0].glyph_for_char(ch).map(Into::into)
222    }
223
224    fn id_for_native_font(&mut self, requested_font: CTFont) -> FontId {
225        let postscript_name = requested_font.postscript_name();
226        if let Some(font_id) = self.font_ids_by_postscript_name.get(&postscript_name) {
227            *font_id
228        } else {
229            let font_id = FontId(self.fonts.len());
230            self.font_ids_by_postscript_name
231                .insert(postscript_name.clone(), font_id);
232            self.postscript_names_by_font_id
233                .insert(font_id, postscript_name);
234            self.fonts
235                .push(font_kit::font::Font::from_core_graphics_font(
236                    requested_font.copy_to_CGFont(),
237                ));
238            font_id
239        }
240    }
241
242    fn is_emoji(&self, font_id: FontId) -> bool {
243        self.postscript_names_by_font_id
244            .get(&font_id)
245            .map_or(false, |postscript_name| {
246                postscript_name == "AppleColorEmoji"
247            })
248    }
249
250    fn rasterize_glyph(
251        &self,
252        font_id: FontId,
253        font_size: f32,
254        glyph_id: GlyphId,
255        subpixel_shift: Point<Pixels>,
256        scale_factor: f32,
257        options: RasterizationOptions,
258    ) -> Option<(Bounds<u32>, Vec<u8>)> {
259        let font = &self.fonts[font_id.0];
260        let scale = Transform2F::from_scale(scale_factor);
261        let glyph_bounds = font
262            .raster_bounds(
263                glyph_id.into(),
264                font_size,
265                scale,
266                HintingOptions::None,
267                font_kit::canvas::RasterizationOptions::GrayscaleAa,
268            )
269            .ok()?;
270
271        if glyph_bounds.width() == 0 || glyph_bounds.height() == 0 {
272            None
273        } else {
274            // Make room for subpixel variants.
275            let subpixel_padding = subpixel_shift.map(|v| f32::from(v).ceil() as u32);
276            let cx_bounds = RectI::new(
277                glyph_bounds.origin(),
278                glyph_bounds.size() + Vector2I::from(subpixel_padding),
279            );
280
281            let mut bytes;
282            let cx;
283            match options {
284                RasterizationOptions::Alpha => {
285                    bytes = vec![0; cx_bounds.width() as usize * cx_bounds.height() as usize];
286                    cx = CGContext::create_bitmap_context(
287                        Some(bytes.as_mut_ptr() as *mut _),
288                        cx_bounds.width() as usize,
289                        cx_bounds.height() as usize,
290                        8,
291                        cx_bounds.width() as usize,
292                        &CGColorSpace::create_device_gray(),
293                        kCGImageAlphaOnly,
294                    );
295                }
296                RasterizationOptions::Bgra => {
297                    bytes = vec![0; cx_bounds.width() as usize * 4 * cx_bounds.height() as usize];
298                    cx = CGContext::create_bitmap_context(
299                        Some(bytes.as_mut_ptr() as *mut _),
300                        cx_bounds.width() as usize,
301                        cx_bounds.height() as usize,
302                        8,
303                        cx_bounds.width() as usize * 4,
304                        &CGColorSpace::create_device_rgb(),
305                        kCGImageAlphaPremultipliedLast,
306                    );
307                }
308            }
309
310            // Move the origin to bottom left and account for scaling, this
311            // makes drawing text consistent with the font-kit's raster_bounds.
312            cx.translate(
313                -glyph_bounds.origin_x() as CGFloat,
314                (glyph_bounds.origin_y() + glyph_bounds.height()) as CGFloat,
315            );
316            cx.scale(scale_factor as CGFloat, scale_factor as CGFloat);
317
318            cx.set_allows_font_subpixel_positioning(true);
319            cx.set_should_subpixel_position_fonts(true);
320            cx.set_allows_font_subpixel_quantization(false);
321            cx.set_should_subpixel_quantize_fonts(false);
322            font.native_font()
323                .clone_with_font_size(font_size as CGFloat)
324                .draw_glyphs(
325                    &[u32::from(glyph_id) as CGGlyph],
326                    &[CGPoint::new(
327                        (f32::from(subpixel_shift.x) / scale_factor) as CGFloat,
328                        (f32::from(subpixel_shift.y) / scale_factor) as CGFloat,
329                    )],
330                    cx,
331                );
332
333            if let RasterizationOptions::Bgra = options {
334                // Convert from RGBA with premultiplied alpha to BGRA with straight alpha.
335                for pixel in bytes.chunks_exact_mut(4) {
336                    pixel.swap(0, 2);
337                    let a = pixel[3] as f32 / 255.;
338                    pixel[0] = (pixel[0] as f32 / a) as u8;
339                    pixel[1] = (pixel[1] as f32 / a) as u8;
340                    pixel[2] = (pixel[2] as f32 / a) as u8;
341                }
342            }
343
344            Some((cx_bounds.into(), bytes))
345        }
346    }
347
348    fn layout_line(
349        &mut self,
350        text: &str,
351        font_size: Pixels,
352        runs: &[(usize, RunStyle)],
353    ) -> LineLayout {
354        // Construct the attributed string, converting UTF8 ranges to UTF16 ranges.
355        let mut string = CFMutableAttributedString::new();
356        {
357            string.replace_str(&CFString::new(text), CFRange::init(0, 0));
358            let utf16_line_len = string.char_len() as usize;
359
360            let last_run: RefCell<Option<(usize, FontId)>> = Default::default();
361            let font_runs = runs
362                .iter()
363                .filter_map(|(len, style)| {
364                    let mut last_run = last_run.borrow_mut();
365                    if let Some((last_len, last_font_id)) = last_run.as_mut() {
366                        if style.font_id == *last_font_id {
367                            *last_len += *len;
368                            None
369                        } else {
370                            let result = (*last_len, *last_font_id);
371                            *last_len = *len;
372                            *last_font_id = style.font_id;
373                            Some(result)
374                        }
375                    } else {
376                        *last_run = Some((*len, style.font_id));
377                        None
378                    }
379                })
380                .chain(std::iter::from_fn(|| last_run.borrow_mut().take()));
381
382            let mut ix_converter = StringIndexConverter::new(text);
383            for (run_len, font_id) in font_runs {
384                let utf8_end = ix_converter.utf8_ix + run_len;
385                let utf16_start = ix_converter.utf16_ix;
386
387                if utf16_start >= utf16_line_len {
388                    break;
389                }
390
391                ix_converter.advance_to_utf8_ix(utf8_end);
392                let utf16_end = cmp::min(ix_converter.utf16_ix, utf16_line_len);
393
394                let cf_range =
395                    CFRange::init(utf16_start as isize, (utf16_end - utf16_start) as isize);
396                let font = &self.fonts[font_id.0];
397                unsafe {
398                    string.set_attribute(
399                        cf_range,
400                        kCTFontAttributeName,
401                        &font.native_font().clone_with_font_size(font_size.into()),
402                    );
403                }
404
405                if utf16_end == utf16_line_len {
406                    break;
407                }
408            }
409        }
410
411        // Retrieve the glyphs from the shaped line, converting UTF16 offsets to UTF8 offsets.
412        let line = CTLine::new_with_attributed_string(string.as_concrete_TypeRef());
413
414        let mut runs = Vec::new();
415        for run in line.glyph_runs().into_iter() {
416            let attributes = run.attributes().unwrap();
417            let font = unsafe {
418                attributes
419                    .get(kCTFontAttributeName)
420                    .downcast::<CTFont>()
421                    .unwrap()
422            };
423            let font_id = self.id_for_native_font(font);
424
425            let mut ix_converter = StringIndexConverter::new(text);
426            let mut glyphs = Vec::new();
427            for ((glyph_id, position), glyph_utf16_ix) in run
428                .glyphs()
429                .iter()
430                .zip(run.positions().iter())
431                .zip(run.string_indices().iter())
432            {
433                let glyph_utf16_ix = usize::try_from(*glyph_utf16_ix).unwrap();
434                ix_converter.advance_to_utf16_ix(glyph_utf16_ix);
435                glyphs.push(Glyph {
436                    id: (*glyph_id).into(),
437                    position: point(position.x as f32, position.y as f32).map(px),
438                    index: ix_converter.utf8_ix,
439                    is_emoji: self.is_emoji(font_id),
440                });
441            }
442
443            runs.push(Run { font_id, glyphs })
444        }
445
446        let typographic_bounds = line.get_typographic_bounds();
447        LineLayout {
448            width: typographic_bounds.width.into(),
449            ascent: typographic_bounds.ascent.into(),
450            descent: typographic_bounds.descent.into(),
451            runs,
452            font_size,
453            len: text.len(),
454        }
455    }
456
457    fn wrap_line(
458        &self,
459        text: &str,
460        font_id: FontId,
461        font_size: Pixels,
462        width: Pixels,
463    ) -> Vec<usize> {
464        let mut string = CFMutableAttributedString::new();
465        string.replace_str(&CFString::new(text), CFRange::init(0, 0));
466        let cf_range = CFRange::init(0, text.encode_utf16().count() as isize);
467        let font = &self.fonts[font_id.0];
468        unsafe {
469            string.set_attribute(
470                cf_range,
471                kCTFontAttributeName,
472                &font.native_font().clone_with_font_size(font_size.into()),
473            );
474
475            let typesetter = CTTypesetterCreateWithAttributedString(string.as_concrete_TypeRef());
476            let mut ix_converter = StringIndexConverter::new(text);
477            let mut break_indices = Vec::new();
478            while ix_converter.utf8_ix < text.len() {
479                let utf16_len = CTTypesetterSuggestLineBreak(
480                    typesetter,
481                    ix_converter.utf16_ix as isize,
482                    width.into(),
483                ) as usize;
484                ix_converter.advance_to_utf16_ix(ix_converter.utf16_ix + utf16_len);
485                if ix_converter.utf8_ix >= text.len() {
486                    break;
487                }
488                break_indices.push(ix_converter.utf8_ix as usize);
489            }
490            break_indices
491        }
492    }
493}
494
495#[derive(Clone)]
496struct StringIndexConverter<'a> {
497    text: &'a str,
498    utf8_ix: usize,
499    utf16_ix: usize,
500}
501
502impl<'a> StringIndexConverter<'a> {
503    fn new(text: &'a str) -> Self {
504        Self {
505            text,
506            utf8_ix: 0,
507            utf16_ix: 0,
508        }
509    }
510
511    fn advance_to_utf8_ix(&mut self, utf8_target: usize) {
512        for (ix, c) in self.text[self.utf8_ix..].char_indices() {
513            if self.utf8_ix + ix >= utf8_target {
514                self.utf8_ix += ix;
515                return;
516            }
517            self.utf16_ix += c.len_utf16();
518        }
519        self.utf8_ix = self.text.len();
520    }
521
522    fn advance_to_utf16_ix(&mut self, utf16_target: usize) {
523        for (ix, c) in self.text[self.utf8_ix..].char_indices() {
524            if self.utf16_ix >= utf16_target {
525                self.utf8_ix += ix;
526                return;
527            }
528            self.utf16_ix += c.len_utf16();
529        }
530        self.utf8_ix = self.text.len();
531    }
532}
533
534#[repr(C)]
535pub struct __CFTypesetter(c_void);
536
537pub type CTTypesetterRef = *const __CFTypesetter;
538
539#[link(name = "CoreText", kind = "framework")]
540extern "C" {
541    fn CTTypesetterCreateWithAttributedString(string: CFAttributedStringRef) -> CTTypesetterRef;
542
543    fn CTTypesetterSuggestLineBreak(
544        typesetter: CTTypesetterRef,
545        start_index: CFIndex,
546        width: f64,
547    ) -> CFIndex;
548}
549
550impl From<Metrics> for FontMetrics {
551    fn from(metrics: Metrics) -> Self {
552        FontMetrics {
553            units_per_em: metrics.units_per_em,
554            ascent: metrics.ascent,
555            descent: metrics.descent,
556            line_gap: metrics.line_gap,
557            underline_position: metrics.underline_position,
558            underline_thickness: metrics.underline_thickness,
559            cap_height: metrics.cap_height,
560            x_height: metrics.x_height,
561            bounding_box: metrics.bounding_box.into(),
562        }
563    }
564}
565
566impl From<RectF> for Bounds<f32> {
567    fn from(rect: RectF) -> Self {
568        Bounds {
569            origin: point(rect.origin_x(), rect.origin_y()),
570            size: size(rect.width(), rect.height()),
571        }
572    }
573}
574
575impl From<RectI> for Bounds<u32> {
576    fn from(rect: RectI) -> Self {
577        Bounds {
578            origin: point(rect.origin_x() as u32, rect.origin_y() as u32),
579            size: size(rect.width() as u32, rect.height() as u32),
580        }
581    }
582}
583
584impl From<Point<u32>> for Vector2I {
585    fn from(size: Point<u32>) -> Self {
586        Vector2I::new(size.x as i32, size.y as i32)
587    }
588}
589
590impl From<Vector2F> for Size<f32> {
591    fn from(vec: Vector2F) -> Self {
592        size(vec.x(), vec.y())
593    }
594}
595
596impl From<FontWeight> for FontkitWeight {
597    fn from(value: FontWeight) -> Self {
598        FontkitWeight(value.0)
599    }
600}
601
602impl From<FontStyle> for FontkitStyle {
603    fn from(style: FontStyle) -> Self {
604        match style {
605            FontStyle::Normal => FontkitStyle::Normal,
606            FontStyle::Italic => FontkitStyle::Italic,
607            FontStyle::Oblique => FontkitStyle::Oblique,
608        }
609    }
610}
611
612// #[cfg(test)]
613// mod tests {
614//     use super::*;
615//     use crate::AppContext;
616//     use font_kit::properties::{Style, Weight};
617//     use platform::FontSystem as _;
618
619//     #[crate::test(self, retries = 5)]
620//     fn test_layout_str(_: &mut AppContext) {
621//         // This is failing intermittently on CI and we don't have time to figure it out
622//         let fonts = FontSystem::new();
623//         let menlo = fonts.load_family("Menlo", &Default::default()).unwrap();
624//         let menlo_regular = RunStyle {
625//             font_id: fonts.select_font(&menlo, &Properties::new()).unwrap(),
626//             color: Default::default(),
627//             underline: Default::default(),
628//         };
629//         let menlo_italic = RunStyle {
630//             font_id: fonts
631//                 .select_font(&menlo, Properties::new().style(Style::Italic))
632//                 .unwrap(),
633//             color: Default::default(),
634//             underline: Default::default(),
635//         };
636//         let menlo_bold = RunStyle {
637//             font_id: fonts
638//                 .select_font(&menlo, Properties::new().weight(Weight::BOLD))
639//                 .unwrap(),
640//             color: Default::default(),
641//             underline: Default::default(),
642//         };
643//         assert_ne!(menlo_regular, menlo_italic);
644//         assert_ne!(menlo_regular, menlo_bold);
645//         assert_ne!(menlo_italic, menlo_bold);
646
647//         let line = fonts.layout_line(
648//             "hello world",
649//             16.0,
650//             &[(2, menlo_bold), (4, menlo_italic), (5, menlo_regular)],
651//         );
652//         assert_eq!(line.runs.len(), 3);
653//         assert_eq!(line.runs[0].font_id, menlo_bold.font_id);
654//         assert_eq!(line.runs[0].glyphs.len(), 2);
655//         assert_eq!(line.runs[1].font_id, menlo_italic.font_id);
656//         assert_eq!(line.runs[1].glyphs.len(), 4);
657//         assert_eq!(line.runs[2].font_id, menlo_regular.font_id);
658//         assert_eq!(line.runs[2].glyphs.len(), 5);
659//     }
660
661//     #[test]
662//     fn test_glyph_offsets() -> anyhow::Result<()> {
663//         let fonts = FontSystem::new();
664//         let zapfino = fonts.load_family("Zapfino", &Default::default())?;
665//         let zapfino_regular = RunStyle {
666//             font_id: fonts.select_font(&zapfino, &Properties::new())?,
667//             color: Default::default(),
668//             underline: Default::default(),
669//         };
670//         let menlo = fonts.load_family("Menlo", &Default::default())?;
671//         let menlo_regular = RunStyle {
672//             font_id: fonts.select_font(&menlo, &Properties::new())?,
673//             color: Default::default(),
674//             underline: Default::default(),
675//         };
676
677//         let text = "This is, m𐍈re 𐍈r less, Zapfino!𐍈";
678//         let line = fonts.layout_line(
679//             text,
680//             16.0,
681//             &[
682//                 (9, zapfino_regular),
683//                 (13, menlo_regular),
684//                 (text.len() - 22, zapfino_regular),
685//             ],
686//         );
687//         assert_eq!(
688//             line.runs
689//                 .iter()
690//                 .flat_map(|r| r.glyphs.iter())
691//                 .map(|g| g.index)
692//                 .collect::<Vec<_>>(),
693//             vec![0, 2, 4, 5, 7, 8, 9, 10, 14, 15, 16, 17, 21, 22, 23, 24, 26, 27, 28, 29, 36, 37],
694//         );
695//         Ok(())
696//     }
697
698//     #[test]
699//     #[ignore]
700//     fn test_rasterize_glyph() {
701//         use std::{fs::File, io::BufWriter, path::Path};
702
703//         let fonts = FontSystem::new();
704//         let font_ids = fonts.load_family("Fira Code", &Default::default()).unwrap();
705//         let font_id = fonts.select_font(&font_ids, &Default::default()).unwrap();
706//         let glyph_id = fonts.glyph_for_char(font_id, 'G').unwrap();
707
708//         const VARIANTS: usize = 1;
709//         for i in 0..VARIANTS {
710//             let variant = i as f32 / VARIANTS as f32;
711//             let (bounds, bytes) = fonts
712//                 .rasterize_glyph(
713//                     font_id,
714//                     16.0,
715//                     glyph_id,
716//                     vec2f(variant, variant),
717//                     2.,
718//                     RasterizationOptions::Alpha,
719//                 )
720//                 .unwrap();
721
722//             let name = format!("/Users/as-cii/Desktop/twog-{}.png", i);
723//             let path = Path::new(&name);
724//             let file = File::create(path).unwrap();
725//             let w = &mut BufWriter::new(file);
726
727//             let mut encoder = png::Encoder::new(w, bounds.width() as u32, bounds.height() as u32);
728//             encoder.set_color(png::ColorType::Grayscale);
729//             encoder.set_depth(png::BitDepth::Eight);
730//             let mut writer = encoder.write_header().unwrap();
731//             writer.write_image_data(&bytes).unwrap();
732//         }
733//     }
734
735//     #[test]
736//     fn test_wrap_line() {
737//         let fonts = FontSystem::new();
738//         let font_ids = fonts.load_family("Helvetica", &Default::default()).unwrap();
739//         let font_id = fonts.select_font(&font_ids, &Default::default()).unwrap();
740
741//         let line = "one two three four five\n";
742//         let wrap_boundaries = fonts.wrap_line(line, font_id, 16., 64.0);
743//         assert_eq!(wrap_boundaries, &["one two ".len(), "one two three ".len()]);
744
745//         let line = "aaa Ξ±Ξ±Ξ± βœ‹βœ‹βœ‹ πŸŽ‰πŸŽ‰πŸŽ‰\n";
746//         let wrap_boundaries = fonts.wrap_line(line, font_id, 16., 64.0);
747//         assert_eq!(
748//             wrap_boundaries,
749//             &["aaa Ξ±Ξ±Ξ± ".len(), "aaa Ξ±Ξ±Ξ± βœ‹βœ‹βœ‹ ".len(),]
750//         );
751//     }
752
753//     #[test]
754//     fn test_layout_line_bom_char() {
755//         let fonts = FontSystem::new();
756//         let font_ids = fonts.load_family("Helvetica", &Default::default()).unwrap();
757//         let style = RunStyle {
758//             font_id: fonts.select_font(&font_ids, &Default::default()).unwrap(),
759//             color: Default::default(),
760//             underline: Default::default(),
761//         };
762
763//         let line = "\u{feff}";
764//         let layout = fonts.layout_line(line, 16., &[(line.len(), style)]);
765//         assert_eq!(layout.len, line.len());
766//         assert!(layout.runs.is_empty());
767
768//         let line = "a\u{feff}b";
769//         let layout = fonts.layout_line(line, 16., &[(line.len(), style)]);
770//         assert_eq!(layout.len, line.len());
771//         assert_eq!(layout.runs.len(), 1);
772//         assert_eq!(layout.runs[0].glyphs.len(), 2);
773//         assert_eq!(layout.runs[0].glyphs[0].id, 68); // a
774//                                                      // There's no glyph for \u{feff}
775//         assert_eq!(layout.runs[0].glyphs[1].id, 69); // b
776//     }
777// }