makepad_rustybuzz/
face.rs

1use crate::ttf_parser::GlyphId;
2use crate::ttf_parser::gdef::GlyphClass;
3use crate::ttf_parser::opentype_layout::LayoutTable;
4
5use crate::Variation;
6use crate::ot::{TableIndex, PositioningTable, SubstitutionTable};
7use crate::buffer::GlyphPropsFlags;
8
9
10// https://docs.microsoft.com/en-us/typography/opentype/spec/cmap#windows-platform-platform-id--3
11const WINDOWS_SYMBOL_ENCODING: u16 = 0;
12const WINDOWS_UNICODE_BMP_ENCODING: u16 = 1;
13const WINDOWS_UNICODE_FULL_ENCODING: u16 = 10;
14
15// https://docs.microsoft.com/en-us/typography/opentype/spec/name#platform-specific-encoding-and-language-ids-unicode-platform-platform-id--0
16const UNICODE_1_0_ENCODING: u16 = 0;
17const UNICODE_1_1_ENCODING: u16 = 1;
18const UNICODE_ISO_ENCODING: u16 = 2;
19const UNICODE_2_0_BMP_ENCODING: u16 = 3;
20const UNICODE_2_0_FULL_ENCODING: u16 = 4;
21//const UNICODE_VARIATION_ENCODING: u16 = 5;
22const UNICODE_FULL_ENCODING: u16 = 6;
23
24
25/// A font face handle.
26#[derive(Clone)]
27pub struct Face<'a> {
28    pub(crate) ttfp_face: crate::ttf_parser::Face<'a>,
29    pub(crate) units_per_em: u16,
30    pixels_per_em: Option<(u16, u16)>,
31    pub(crate) points_per_em: Option<f32>,
32    prefered_cmap_encoding_subtable: Option<u16>,
33    pub(crate) gsub: Option<SubstitutionTable<'a>>,
34    pub(crate) gpos: Option<PositioningTable<'a>>,
35}
36
37impl<'a> AsRef<crate::ttf_parser::Face<'a>> for Face<'a> {
38    #[inline]
39    fn as_ref(&self) -> &crate::ttf_parser::Face<'a> {
40        &self.ttfp_face
41    }
42}
43
44impl<'a> AsMut<crate::ttf_parser::Face<'a>> for Face<'a> {
45    #[inline]
46    fn as_mut(&mut self) -> &mut crate::ttf_parser::Face<'a> {
47        &mut self.ttfp_face
48    }
49}
50
51impl<'a> core::ops::Deref for Face<'a> {
52    type Target = crate::ttf_parser::Face<'a>;
53
54    #[inline]
55    fn deref(&self) -> &Self::Target {
56        &self.ttfp_face
57    }
58}
59
60impl<'a> core::ops::DerefMut for Face<'a> {
61    #[inline]
62    fn deref_mut(&mut self) -> &mut Self::Target {
63        &mut self.ttfp_face
64    }
65}
66
67impl<'a> Face<'a> {
68    /// Creates a new `Face` from data.
69    ///
70    /// Data will be referenced, not owned.
71    pub fn from_slice(data: &'a [u8], face_index: u32) -> Option<Self> {
72        let face = crate::ttf_parser::Face::parse(data, face_index).ok()?;
73        Some(Self::from_face(face))
74    }
75
76    /// Creates a new [`Face`] from [`ttf_parser::Face`].
77    ///
78    /// Data will be referenced, not owned.
79    pub fn from_face(face: crate::ttf_parser::Face<'a>) -> Self {
80        Face {
81            units_per_em: face.units_per_em(),
82            pixels_per_em: None,
83            points_per_em: None,
84            prefered_cmap_encoding_subtable: find_best_cmap_subtable(&face),
85            gsub: face.tables().gsub.map(SubstitutionTable::new),
86            gpos: face.tables().gpos.map(PositioningTable::new),
87            ttfp_face: face,
88        }
89    }
90
91    // TODO: remove
92    /// Returns face’s units per EM.
93    #[inline]
94    pub fn units_per_em(&self) -> i32 {
95        self.units_per_em as i32
96    }
97
98    #[inline]
99    pub(crate) fn pixels_per_em(&self) -> Option<(u16, u16)> {
100        self.pixels_per_em
101    }
102
103    /// Sets pixels per EM.
104    ///
105    /// Used during raster glyphs processing and hinting.
106    ///
107    /// `None` by default.
108    #[inline]
109    pub fn set_pixels_per_em(&mut self, ppem: Option<(u16, u16)>) {
110        self.pixels_per_em = ppem;
111    }
112
113    /// Sets point size per EM.
114    ///
115    /// Used for optical-sizing in Apple fonts.
116    ///
117    /// `None` by default.
118    #[inline]
119    pub fn set_points_per_em(&mut self, ptem: Option<f32>) {
120        self.points_per_em = ptem;
121    }
122
123    /// Sets font variations.
124    pub fn set_variations(&mut self, variations: &[Variation]) {
125        for variation in variations {
126            self.set_variation(variation.tag, variation.value);
127        }
128    }
129
130    pub(crate) fn has_glyph(&self, c: u32) -> bool {
131        self.glyph_index(c).is_some()
132    }
133
134    pub(crate) fn glyph_index(&self, c: u32) -> Option<GlyphId> {
135        let subtable_idx = self.prefered_cmap_encoding_subtable?;
136        let subtable = self.tables().cmap?.subtables.get(subtable_idx)?;
137        match subtable.glyph_index(c) {
138            Some(gid) => Some(gid),
139            None => {
140                // Special case for Windows Symbol fonts.
141                // TODO: add tests
142                if  subtable.platform_id == crate::ttf_parser::PlatformId::Windows &&
143                    subtable.encoding_id == WINDOWS_SYMBOL_ENCODING
144                {
145                    if c <= 0x00FF {
146                        // For symbol-encoded OpenType fonts, we duplicate the
147                        // U+F000..F0FF range at U+0000..U+00FF.  That's what
148                        // Windows seems to do, and that's hinted about at:
149                        // https://docs.microsoft.com/en-us/typography/opentype/spec/recom
150                        // under "Non-Standard (Symbol) Fonts".
151                        return self.glyph_index(0xF000 + c);
152                    }
153                }
154
155                None
156            }
157        }
158    }
159
160    pub(crate) fn glyph_h_advance(&self, glyph: GlyphId) -> i32 {
161        self.glyph_advance(glyph, false) as i32
162    }
163
164    pub(crate) fn glyph_v_advance(&self, glyph: GlyphId) -> i32 {
165        -(self.glyph_advance(glyph, true) as i32)
166    }
167
168    fn glyph_advance(&self, glyph: GlyphId, is_vertical: bool) -> u32 {
169        let face = &self.ttfp_face;
170        if face.is_variable() &&
171           face.has_non_default_variation_coordinates() &&
172           face.tables().hvar.is_none() &&
173           face.tables().vvar.is_none()
174        {
175            return match face.glyph_bounding_box(glyph) {
176                Some(bbox) => {
177                    (if is_vertical {
178                        bbox.y_max + bbox.y_min
179                    } else {
180                        bbox.x_max + bbox.x_min
181                    }) as u32
182                }
183                None => 0,
184            };
185        }
186
187        if is_vertical && face.tables().vmtx.is_some() {
188            face.glyph_ver_advance(glyph).unwrap_or(0) as u32
189        } else if !is_vertical && face.tables().hmtx.is_some() {
190            face.glyph_hor_advance(glyph).unwrap_or(0) as u32
191        } else {
192            face.units_per_em() as u32
193        }
194    }
195
196    pub(crate) fn glyph_h_origin(&self, glyph: GlyphId) -> i32 {
197        self.glyph_h_advance(glyph) / 2
198    }
199
200    pub(crate) fn glyph_v_origin(&self, glyph: GlyphId) -> i32 {
201        match self.ttfp_face.glyph_y_origin(glyph) {
202            Some(y) => i32::from(y),
203            None => self.glyph_extents(glyph).map_or(0, |ext| ext.y_bearing)
204                + self.glyph_side_bearing(glyph, true)
205        }
206    }
207
208    pub(crate) fn glyph_side_bearing(&self, glyph: GlyphId, is_vertical: bool) -> i32 {
209        let face = &self.ttfp_face;
210        if  face.is_variable() &&
211            face.tables().hvar.is_none() &&
212            face.tables().vvar.is_none()
213        {
214            return match face.glyph_bounding_box(glyph) {
215                Some(bbox) => (if is_vertical { bbox.x_min } else { bbox.y_min }) as i32,
216                None => 0,
217            }
218        }
219
220        if is_vertical {
221            face.glyph_ver_side_bearing(glyph).unwrap_or(0) as i32
222        } else {
223            face.glyph_hor_side_bearing(glyph).unwrap_or(0) as i32
224        }
225    }
226
227    pub(crate) fn glyph_extents(&self, glyph: GlyphId) -> Option<GlyphExtents> {
228        let pixels_per_em = match self.pixels_per_em {
229            Some(ppem) => ppem.0,
230            None => core::u16::MAX,
231        };
232
233        if let Some(img) = self.ttfp_face.glyph_raster_image(glyph, pixels_per_em) {
234            // HarfBuzz also supports only PNG.
235            if img.format == crate::ttf_parser::RasterImageFormat::PNG {
236                let scale = self.units_per_em as f32 / img.pixels_per_em as f32;
237                return Some(GlyphExtents {
238                    x_bearing: crate::round(f32::from(img.x) * scale) as i32,
239                    y_bearing: crate::round((f32::from(img.y) + f32::from(img.height)) * scale) as i32,
240                    width: crate::round(f32::from(img.width) * scale) as i32,
241                    height: crate::round(-f32::from(img.height) * scale) as i32,
242                });
243            }
244        }
245
246        let bbox = self.ttfp_face.glyph_bounding_box(glyph)?;
247        Some(GlyphExtents {
248            x_bearing: i32::from(bbox.x_min),
249            y_bearing: i32::from(bbox.y_max),
250            width: i32::from(bbox.width()),
251            height: i32::from(bbox.y_min - bbox.y_max),
252        })
253    }
254
255    pub(crate) fn glyph_name(&self, glyph: GlyphId) -> Option<&str> {
256        self.ttfp_face.glyph_name(glyph)
257    }
258
259    pub(crate) fn glyph_props(&self, glyph: GlyphId) -> u16 {
260        let table = match self.tables().gdef {
261            Some(v) => v,
262            None => return 0,
263        };
264
265        match table.glyph_class(glyph) {
266            Some(GlyphClass::Base) => GlyphPropsFlags::BASE_GLYPH.bits(),
267            Some(GlyphClass::Ligature) => GlyphPropsFlags::LIGATURE.bits(),
268            Some(GlyphClass::Mark) => {
269                let class = table.glyph_mark_attachment_class(glyph);
270                (class << 8) | GlyphPropsFlags::MARK.bits()
271            }
272            _ => 0,
273        }
274    }
275
276    pub(crate) fn layout_table(&self, table_index: TableIndex) -> Option<&LayoutTable<'a>> {
277        match table_index {
278            TableIndex::GSUB => self.gsub.as_ref().map(|table| &table.inner),
279            TableIndex::GPOS => self.gpos.as_ref().map(|table| &table.inner),
280        }
281    }
282
283    pub(crate) fn layout_tables(&self) -> impl Iterator<Item = (TableIndex, &LayoutTable<'a>)> + '_ {
284        TableIndex::iter().filter_map(move |idx| self.layout_table(idx).map(|table| (idx, table)))
285    }
286}
287
288#[derive(Clone, Copy, Default)]
289pub struct GlyphExtents {
290    pub x_bearing: i32,
291    pub y_bearing: i32,
292    pub width: i32,
293    pub height: i32,
294}
295
296fn find_best_cmap_subtable(face: &crate::ttf_parser::Face) -> Option<u16> {
297    use crate::ttf_parser::PlatformId;
298
299    // Symbol subtable.
300    // Prefer symbol if available.
301    // https://github.com/harfbuzz/harfbuzz/issues/1918
302    find_cmap_subtable(face, PlatformId::Windows, WINDOWS_SYMBOL_ENCODING)
303        // 32-bit subtables:
304        .or_else(|| find_cmap_subtable(face, PlatformId::Windows, WINDOWS_UNICODE_FULL_ENCODING))
305        .or_else(|| find_cmap_subtable(face, PlatformId::Unicode, UNICODE_FULL_ENCODING))
306        .or_else(|| find_cmap_subtable(face, PlatformId::Unicode, UNICODE_2_0_FULL_ENCODING))
307        // 16-bit subtables:
308        .or_else(|| find_cmap_subtable(face, PlatformId::Windows, WINDOWS_UNICODE_BMP_ENCODING))
309        .or_else(|| find_cmap_subtable(face, PlatformId::Unicode, UNICODE_2_0_BMP_ENCODING))
310        .or_else(|| find_cmap_subtable(face, PlatformId::Unicode, UNICODE_ISO_ENCODING))
311        .or_else(|| find_cmap_subtable(face, PlatformId::Unicode, UNICODE_1_1_ENCODING))
312        .or_else(|| find_cmap_subtable(face, PlatformId::Unicode, UNICODE_1_0_ENCODING))
313}
314
315fn find_cmap_subtable(
316    face: &crate::ttf_parser::Face,
317    platform_id: crate::ttf_parser::PlatformId,
318    encoding_id: u16,
319) -> Option<u16> {
320    for (i, subtable) in face.tables().cmap?.subtables.into_iter().enumerate() {
321        if subtable.platform_id == platform_id && subtable.encoding_id == encoding_id {
322            return Some(i as u16)
323        }
324    }
325
326    None
327}
makepad_rustybuzz/face.rs

makepad_rustybuzz/
face.rs
