ttf_parser/
ggg.rs

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1//! Common types for GDEF, GPOS and GSUB tables.
2
3use crate::GlyphId;
4use crate::parser::*;
5
6
7#[derive(Clone, Copy)]
8struct RangeRecord {
9    start_glyph_id: GlyphId,
10    end_glyph_id: GlyphId,
11    value: u16,
12}
13
14impl RangeRecord {
15    fn range(&self) -> core::ops::RangeInclusive<GlyphId> {
16        self.start_glyph_id..=self.end_glyph_id
17    }
18}
19
20impl FromData for RangeRecord {
21    const SIZE: usize = 6;
22
23    #[inline]
24    fn parse(data: &[u8]) -> Option<Self> {
25        let mut s = Stream::new(data);
26        Some(RangeRecord {
27            start_glyph_id: s.read::<GlyphId>()?,
28            end_glyph_id: s.read::<GlyphId>()?,
29            value: s.read::<u16>()?,
30        })
31    }
32}
33
34
35/// A [Coverage Table](https://docs.microsoft.com/en-us/typography/opentype/spec/chapter2#coverage-table).
36#[derive(Clone, Copy, Debug)]
37pub(crate) struct CoverageTable<'a> {
38    data: &'a [u8],
39}
40
41impl<'a> CoverageTable<'a> {
42    pub fn new(data: &'a [u8]) -> Self {
43        CoverageTable { data }
44    }
45
46    pub fn contains(&self, glyph_id: GlyphId) -> bool {
47        let mut s = Stream::new(self.data);
48        let format: u16 = try_opt_or!(s.read(), false);
49
50        match format {
51            1 => {
52                let count = try_opt_or!(s.read::<u16>(), false);
53                s.read_array16::<GlyphId>(count).unwrap().binary_search(&glyph_id).is_some()
54            }
55            2 => {
56                let count = try_opt_or!(s.read::<u16>(), false);
57                let records = try_opt_or!(s.read_array16::<RangeRecord>(count), false);
58                records.into_iter().any(|r| r.range().contains(&glyph_id))
59            }
60            _ => false,
61        }
62    }
63}
64
65
66/// A value of [Class Definition Table](https://docs.microsoft.com/en-us/typography/opentype/spec/chapter2#class-definition-table).
67#[repr(C)]
68#[derive(Clone, Copy, PartialEq, Debug)]
69pub struct Class(pub u16);
70
71impl FromData for Class {
72    const SIZE: usize = 2;
73
74    #[inline]
75    fn parse(data: &[u8]) -> Option<Self> {
76        u16::parse(data).map(Class)
77    }
78}
79
80
81/// A [Class Definition Table](https://docs.microsoft.com/en-us/typography/opentype/spec/chapter2#class-definition-table).
82#[derive(Clone, Copy)]
83pub(crate) struct ClassDefinitionTable<'a> {
84    data: &'a [u8],
85}
86
87impl<'a> ClassDefinitionTable<'a> {
88    pub fn new(data: &'a [u8]) -> Self {
89        ClassDefinitionTable { data }
90    }
91
92    /// Any glyph not included in the range of covered glyph IDs automatically belongs to Class 0.
93    pub fn get(&self, glyph_id: GlyphId) -> Class {
94        self.get_impl(glyph_id).unwrap_or(Class(0))
95    }
96
97    fn get_impl(&self, glyph_id: GlyphId) -> Option<Class> {
98        let mut s = Stream::new(self.data);
99        let format: u16 = s.read()?;
100        match format {
101            1 => {
102                let start_glyph_id: GlyphId = s.read()?;
103
104                // Prevent overflow.
105                if glyph_id < start_glyph_id {
106                    return None;
107                }
108
109                let count: u16 = s.read()?;
110                let classes = s.read_array16::<Class>(count)?;
111                classes.get(glyph_id.0 - start_glyph_id.0)
112            }
113            2 => {
114                let count: u16 = s.read()?;
115                let records = s.read_array16::<RangeRecord>(count)?;
116                records.into_iter().find(|r| r.range().contains(&glyph_id))
117                    .map(|record| Class(record.value))
118            }
119            _ => None,
120        }
121    }
122}
ttf_parser/ggg.rs

ttf_parser/
ggg.rs
