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

//! The [MVAR (Metrics Variation)](https://docs.microsoft.com/en-us/typography/opentype/spec/mvar) table

use super::variations::{DeltaSetIndex, ItemVariationStore};

/// Four-byte tags used to represent particular metric or other values.
pub mod tags {
    use font_types::Tag;

    /// Horizontal ascender.
    pub const HASC: Tag = Tag::new(b"hasc");
    /// Horizontal descender.
    pub const HDSC: Tag = Tag::new(b"hdsc");
    /// Horizontal line gap.
    pub const HLGP: Tag = Tag::new(b"hlgp");

    /// Horizontal clipping ascent.
    pub const HCLA: Tag = Tag::new(b"hcla");
    /// Horizontal clipping descent.
    pub const HCLD: Tag = Tag::new(b"hcld");

    /// Vertical ascender.
    pub const VASC: Tag = Tag::new(b"vasc");
    /// Vertical descender.
    pub const VDSC: Tag = Tag::new(b"vdsc");
    /// Vertical line gap.
    pub const VLGP: Tag = Tag::new(b"vlgp");

    /// Horizontal caret rise.
    pub const HCRS: Tag = Tag::new(b"hcrs");
    /// Horizontal caret run.
    pub const HCRN: Tag = Tag::new(b"hcrn");
    /// Horizontal caret offset.
    pub const HCOF: Tag = Tag::new(b"hcof");

    /// Vertical caret rise.
    pub const VCRS: Tag = Tag::new(b"vcrs");
    /// Vertical caret run.
    pub const VCRN: Tag = Tag::new(b"vcrn");
    /// Vertical caret offset.
    pub const VCOF: Tag = Tag::new(b"vcof");

    /// X-height.
    pub const XHGT: Tag = Tag::new(b"xhgt");
    /// Cap height.
    pub const CPHT: Tag = Tag::new(b"cpht");

    /// Subscript em x-offset.
    pub const SBXO: Tag = Tag::new(b"sbxo");
    /// Subscript em y-offset.
    pub const SBYO: Tag = Tag::new(b"sbyo");
    /// Subscript em x-size.
    pub const SBXS: Tag = Tag::new(b"sbxs");
    /// Subscript em y-size.
    pub const SBYS: Tag = Tag::new(b"sbys");

    /// Superscript em x-offset.
    pub const SPXO: Tag = Tag::new(b"spxo");
    /// Superscript em y-offset.
    pub const SPYO: Tag = Tag::new(b"spyo");
    /// Superscript em x-size.
    pub const SPXS: Tag = Tag::new(b"spxs");
    /// Superscript em y-size.
    pub const SPYS: Tag = Tag::new(b"spys");

    /// Strikeout size.
    pub const STRS: Tag = Tag::new(b"strs");
    /// Strikeout offset.
    pub const STRO: Tag = Tag::new(b"stro");

    /// Underline size.
    pub const UNDS: Tag = Tag::new(b"unds");
    /// Underline offset.
    pub const UNDO: Tag = Tag::new(b"undo");

    /// GaspRange\[0\]
    pub const GSP0: Tag = Tag::new(b"gsp0");
    /// GaspRange\[1\]
    pub const GSP1: Tag = Tag::new(b"gsp1");
    /// GaspRange\[2\]
    pub const GSP2: Tag = Tag::new(b"gsp2");
    /// GaspRange\[3\]
    pub const GSP3: Tag = Tag::new(b"gsp3");
    /// GaspRange\[4\]
    pub const GSP4: Tag = Tag::new(b"gsp4");
    /// GaspRange\[5\]
    pub const GSP5: Tag = Tag::new(b"gsp5");
    /// GaspRange\[6\]
    pub const GSP6: Tag = Tag::new(b"gsp6");
    /// GaspRange\[7\]
    pub const GSP7: Tag = Tag::new(b"gsp7");
    /// GaspRange\[8\]
    pub const GSP8: Tag = Tag::new(b"gsp8");
    /// GaspRange\[9\]
    pub const GSP9: Tag = Tag::new(b"gsp9");
}

include!("../../generated/generated_mvar.rs");

impl<'a> Mvar<'a> {
    /// Returns the metric delta for the specified tag and normalized
    /// variation coordinates. Possible tags are found in the [tags]
    /// module.
    pub fn metric_delta(&self, tag: Tag, coords: &[F2Dot14]) -> Result<Fixed, ReadError> {
        use std::cmp::Ordering;
        let records = self.value_records();
        let mut lo = 0;
        let mut hi = records.len();
        while lo < hi {
            let i = (lo + hi) / 2;
            let record = &records[i];
            match tag.cmp(&record.value_tag()) {
                Ordering::Less => {
                    hi = i;
                }
                Ordering::Greater => {
                    lo = i + 1;
                }
                Ordering::Equal => {
                    let ivs = self.item_variation_store().ok_or(ReadError::NullOffset)??;
                    return ivs.compute_delta(
                        DeltaSetIndex {
                            outer: record.delta_set_outer_index(),
                            inner: record.delta_set_inner_index(),
                        },
                        coords,
                    );
                }
            }
        }
        Err(ReadError::MetricIsMissing(tag))
    }
}