1//! A [Vertical Origin Table](
2//! https://docs.microsoft.com/en-us/typography/opentype/spec/vorg) implementation.
3
4use crate::parser::{FromData, LazyArray16, Stream};
5use crate::GlyphId;
6
7/// Vertical origin metrics for the
8/// [Vertical Origin Table](https://docs.microsoft.com/en-us/typography/opentype/spec/vorg).
9#[derive(Clone, Copy, Debug)]
10pub struct VerticalOriginMetrics {
11 /// Glyph ID.
12 pub glyph_id: GlyphId,
13 /// Y coordinate, in the font's design coordinate system, of the vertical origin.
14 pub y: i16,
15}
16
17impl FromData for VerticalOriginMetrics {
18 const SIZE: usize = 4;
19
20 #[inline]
21 fn parse(data: &[u8]) -> Option<Self> {
22 let mut s: Stream<'_> = Stream::new(data);
23 Some(VerticalOriginMetrics {
24 glyph_id: s.read::<GlyphId>()?,
25 y: s.read::<i16>()?,
26 })
27 }
28}
29
30/// A [Vertical Origin Table](https://docs.microsoft.com/en-us/typography/opentype/spec/vorg).
31#[derive(Clone, Copy, Debug)]
32pub struct Table<'a> {
33 /// Default origin.
34 pub default_y: i16,
35 /// A list of metrics for each glyph.
36 ///
37 /// Ordered by `glyph_id`.
38 pub metrics: LazyArray16<'a, VerticalOriginMetrics>,
39}
40
41impl<'a> Table<'a> {
42 /// Parses a table from raw data.
43 pub fn parse(data: &'a [u8]) -> Option<Self> {
44 let mut s = Stream::new(data);
45
46 let version = s.read::<u32>()?;
47 if version != 0x00010000 {
48 return None;
49 }
50
51 let default_y = s.read::<i16>()?;
52 let count = s.read::<u16>()?;
53 let metrics = s.read_array16::<VerticalOriginMetrics>(count)?;
54
55 Some(Table { default_y, metrics })
56 }
57
58 /// Returns glyph's Y origin.
59 pub fn glyph_y_origin(&self, glyph_id: GlyphId) -> i16 {
60 self.metrics
61 .binary_search_by(|m| m.glyph_id.cmp(&glyph_id))
62 .map(|(_, m)| m.y)
63 .unwrap_or(self.default_y)
64 }
65}
66