ttf_parser/tables/
vvar.rs

1//! A [Vertical Metrics Variations Table](
2//! https://docs.microsoft.com/en-us/typography/opentype/spec/hvar) implementation.
3
4use crate::delta_set::DeltaSetIndexMap;
5use crate::parser::{Offset, Offset32, Stream};
6use crate::var_store::ItemVariationStore;
7use crate::{GlyphId, NormalizedCoordinate};
8
9/// A [Vertical Metrics Variations Table](
10/// https://docs.microsoft.com/en-us/typography/opentype/spec/hvar).
11#[derive(Clone, Copy)]
12pub struct Table<'a> {
13    data: &'a [u8],
14    variation_store: ItemVariationStore<'a>,
15    advance_height_mapping_offset: Option<Offset32>,
16    tsb_mapping_offset: Option<Offset32>,
17    bsb_mapping_offset: Option<Offset32>,
18    vorg_mapping_offset: Option<Offset32>,
19}
20
21impl<'a> Table<'a> {
22    /// Parses a table from raw data.
23    pub fn parse(data: &'a [u8]) -> Option<Self> {
24        let mut s = Stream::new(data);
25
26        let version = s.read::<u32>()?;
27        if version != 0x00010000 {
28            return None;
29        }
30
31        let variation_store_offset = s.read::<Offset32>()?;
32        let var_store_s = Stream::new_at(data, variation_store_offset.to_usize())?;
33        let variation_store = ItemVariationStore::parse(var_store_s)?;
34
35        Some(Table {
36            data,
37            variation_store,
38            advance_height_mapping_offset: s.read::<Option<Offset32>>()?,
39            tsb_mapping_offset: s.read::<Option<Offset32>>()?,
40            bsb_mapping_offset: s.read::<Option<Offset32>>()?,
41            vorg_mapping_offset: s.read::<Option<Offset32>>()?,
42        })
43    }
44
45    /// Returns the advance height offset for a glyph.
46    #[inline]
47    pub fn advance_offset(
48        &self,
49        glyph_id: GlyphId,
50        coordinates: &[NormalizedCoordinate],
51    ) -> Option<f32> {
52        let (outer_idx, inner_idx) = if let Some(offset) = self.advance_height_mapping_offset {
53            DeltaSetIndexMap::new(self.data.get(offset.to_usize()..)?).map(glyph_id.0 as u32)?
54        } else {
55            // 'If there is no delta-set index mapping table for advance widths,
56            // then glyph IDs implicitly provide the indices:
57            // for a given glyph ID, the delta-set outer-level index is zero,
58            // and the glyph ID is the delta-set inner-level index.'
59            (0, glyph_id.0)
60        };
61
62        self.variation_store
63            .parse_delta(outer_idx, inner_idx, coordinates)
64    }
65
66    /// Returns the top side bearing offset for a glyph.
67    #[inline]
68    pub fn top_side_bearing_offset(
69        &self,
70        glyph_id: GlyphId,
71        coordinates: &[NormalizedCoordinate],
72    ) -> Option<f32> {
73        let set_data = self.data.get(self.tsb_mapping_offset?.to_usize()..)?;
74        self.side_bearing_offset(glyph_id, coordinates, set_data)
75    }
76
77    /// Returns the bottom side bearing offset for a glyph.
78    #[inline]
79    pub fn bottom_side_bearing_offset(
80        &self,
81        glyph_id: GlyphId,
82        coordinates: &[NormalizedCoordinate],
83    ) -> Option<f32> {
84        let set_data = self.data.get(self.bsb_mapping_offset?.to_usize()..)?;
85        self.side_bearing_offset(glyph_id, coordinates, set_data)
86    }
87
88    /// Returns the vertical origin offset for a glyph.
89    #[inline]
90    pub fn vertical_origin_offset(
91        &self,
92        glyph_id: GlyphId,
93        coordinates: &[NormalizedCoordinate],
94    ) -> Option<f32> {
95        let set_data = self.data.get(self.vorg_mapping_offset?.to_usize()..)?;
96        self.side_bearing_offset(glyph_id, coordinates, set_data)
97    }
98
99    fn side_bearing_offset(
100        &self,
101        glyph_id: GlyphId,
102        coordinates: &[NormalizedCoordinate],
103        set_data: &[u8],
104    ) -> Option<f32> {
105        let (outer_idx, inner_idx) = DeltaSetIndexMap::new(set_data).map(glyph_id.0 as u32)?;
106        self.variation_store
107            .parse_delta(outer_idx, inner_idx, coordinates)
108    }
109}
110
111impl core::fmt::Debug for Table<'_> {
112    fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
113        write!(f, "Table {{ ... }}")
114    }
115}
ttf_parser/tables/vvar.rs

ttf_parser/tables/
vvar.rs
