ttf_parser/tables/
gdef.rs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
//! A [Glyph Definition Table](
//! https://docs.microsoft.com/en-us/typography/opentype/spec/gdef) implementation.

use crate::opentype_layout::{Class, ClassDefinition, Coverage};
use crate::parser::{FromSlice, LazyArray16, Offset, Offset16, Offset32, Stream};
use crate::GlyphId;

#[cfg(feature = "variable-fonts")]
use crate::var_store::ItemVariationStore;
#[cfg(feature = "variable-fonts")]
use crate::NormalizedCoordinate;

/// A [glyph class](https://docs.microsoft.com/en-us/typography/opentype/spec/gdef#glyph-class-definition-table).
#[allow(missing_docs)]
#[derive(Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Debug, Hash)]
pub enum GlyphClass {
    Base = 1,
    Ligature = 2,
    Mark = 3,
    Component = 4,
}

/// A [Glyph Definition Table](https://docs.microsoft.com/en-us/typography/opentype/spec/gdef).
#[allow(missing_debug_implementations)]
#[derive(Clone, Copy, Default)]
pub struct Table<'a> {
    glyph_classes: Option<ClassDefinition<'a>>,
    mark_attach_classes: Option<ClassDefinition<'a>>,
    mark_glyph_coverage_offsets: Option<(&'a [u8], LazyArray16<'a, Offset32>)>,
    #[cfg(feature = "variable-fonts")]
    variation_store: Option<ItemVariationStore<'a>>,
}

impl<'a> Table<'a> {
    /// Parses a table from raw data.
    pub fn parse(data: &'a [u8]) -> Option<Self> {
        let mut s = Stream::new(data);
        let version = s.read::<u32>()?;
        if !(version == 0x00010000 || version == 0x00010002 || version == 0x00010003) {
            return None;
        }

        let glyph_class_def_offset = s.read::<Option<Offset16>>()?;
        s.skip::<Offset16>(); // attachListOffset
        s.skip::<Offset16>(); // ligCaretListOffset
        let mark_attach_class_def_offset = s.read::<Option<Offset16>>()?;

        let mut mark_glyph_sets_def_offset: Option<Offset16> = None;
        if version > 0x00010000 {
            mark_glyph_sets_def_offset = s.read::<Option<Offset16>>()?;
        }

        #[allow(unused_mut)]
        #[allow(unused_variables)]
        let mut var_store_offset: Option<Offset32> = None;

        #[cfg(feature = "variable-fonts")]
        {
            if version > 0x00010002 {
                var_store_offset = s.read::<Option<Offset32>>()?;
            }
        }

        let mut table = Table::default();

        if let Some(offset) = glyph_class_def_offset {
            if let Some(subdata) = data.get(offset.to_usize()..) {
                table.glyph_classes = ClassDefinition::parse(subdata);
            }
        }

        if let Some(offset) = mark_attach_class_def_offset {
            if let Some(subdata) = data.get(offset.to_usize()..) {
                table.mark_attach_classes = ClassDefinition::parse(subdata);
            }
        }

        if let Some(offset) = mark_glyph_sets_def_offset {
            if let Some(subdata) = data.get(offset.to_usize()..) {
                let mut s = Stream::new(subdata);
                let format = s.read::<u16>()?;
                if format == 1 {
                    if let Some(count) = s.read::<u16>() {
                        if let Some(array) = s.read_array16::<Offset32>(count) {
                            table.mark_glyph_coverage_offsets = Some((subdata, array));
                        }
                    }
                }
            }
        }

        #[cfg(feature = "variable-fonts")]
        {
            if let Some(offset) = var_store_offset {
                if let Some(subdata) = data.get(offset.to_usize()..) {
                    let s = Stream::new(subdata);
                    table.variation_store = ItemVariationStore::parse(s);
                }
            }
        }

        Some(table)
    }

    /// Checks that face has
    /// [Glyph Class Definition Table](
    /// https://docs.microsoft.com/en-us/typography/opentype/spec/gdef#glyph-class-definition-table).
    #[inline]
    pub fn has_glyph_classes(&self) -> bool {
        self.glyph_classes.is_some()
    }

    /// Returns glyph's class according to
    /// [Glyph Class Definition Table](
    /// https://docs.microsoft.com/en-us/typography/opentype/spec/gdef#glyph-class-definition-table).
    ///
    /// Returns `None` when *Glyph Class Definition Table* is not set
    /// or glyph class is not set or invalid.
    #[inline]
    pub fn glyph_class(&self, glyph_id: GlyphId) -> Option<GlyphClass> {
        match self.glyph_classes?.get(glyph_id) {
            1 => Some(GlyphClass::Base),
            2 => Some(GlyphClass::Ligature),
            3 => Some(GlyphClass::Mark),
            4 => Some(GlyphClass::Component),
            _ => None,
        }
    }

    /// Returns glyph's mark attachment class according to
    /// [Mark Attachment Class Definition Table](
    /// https://docs.microsoft.com/en-us/typography/opentype/spec/gdef#mark-attachment-class-definition-table).
    ///
    /// All glyphs not assigned to a class fall into Class 0.
    #[inline]
    pub fn glyph_mark_attachment_class(&self, glyph_id: GlyphId) -> Class {
        self.mark_attach_classes
            .map(|def| def.get(glyph_id))
            .unwrap_or(0)
    }

    /// Checks that glyph is a mark according to
    /// [Mark Glyph Sets Table](
    /// https://docs.microsoft.com/en-us/typography/opentype/spec/gdef#mark-glyph-sets-table).
    ///
    /// `set_index` allows checking a specific glyph coverage set.
    /// Otherwise all sets will be checked.
    #[inline]
    pub fn is_mark_glyph(&self, glyph_id: GlyphId, set_index: Option<u16>) -> bool {
        is_mark_glyph_impl(self, glyph_id, set_index).is_some()
    }

    /// Returns glyph's variation delta at a specified index according to
    /// [Item Variation Store Table](
    /// https://docs.microsoft.com/en-us/typography/opentype/spec/gdef#item-variation-store-table).
    #[cfg(feature = "variable-fonts")]
    #[inline]
    pub fn glyph_variation_delta(
        &self,
        outer_index: u16,
        inner_index: u16,
        coordinates: &[NormalizedCoordinate],
    ) -> Option<f32> {
        self.variation_store
            .and_then(|store| store.parse_delta(outer_index, inner_index, coordinates))
    }
}

#[inline(never)]
fn is_mark_glyph_impl(table: &Table, glyph_id: GlyphId, set_index: Option<u16>) -> Option<()> {
    let (data, offsets) = table.mark_glyph_coverage_offsets?;

    if let Some(set_index) = set_index {
        if let Some(offset) = offsets.get(set_index) {
            let table = Coverage::parse(data.get(offset.to_usize()..)?)?;
            if table.contains(glyph_id) {
                return Some(());
            }
        }
    } else {
        for offset in offsets {
            let table = Coverage::parse(data.get(offset.to_usize()..)?)?;
            if table.contains(glyph_id) {
                return Some(());
            }
        }
    }

    None
}