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//! A [Vertical Origin Table](
//! https://docs.microsoft.com/en-us/typography/opentype/spec/vorg) implementation.
use crate::GlyphId;
use crate::parser::{Stream, FromData, LazyArray16};
/// Vertical origin metrics for the
/// [Vertical Origin Table](https://docs.microsoft.com/en-us/typography/opentype/spec/vorg).
#[derive(Clone, Copy, Debug)]
pub struct VerticalOriginMetrics {
/// Glyph ID.
pub glyph_id: GlyphId,
/// Y coordinate, in the font's design coordinate system, of the vertical origin.
pub y: i16,
}
impl FromData for VerticalOriginMetrics {
const SIZE: usize = 4;
#[inline]
fn parse(data: &[u8]) -> Option<Self> {
let mut s = Stream::new(data);
Some(VerticalOriginMetrics {
glyph_id: s.read::<GlyphId>()?,
y: s.read::<i16>()?,
})
}
}
/// A [Vertical Origin Table](https://docs.microsoft.com/en-us/typography/opentype/spec/vorg).
#[derive(Clone, Copy, Debug)]
pub struct Table<'a> {
/// Default origin.
pub default_y: i16,
/// A list of metrics for each glyph.
///
/// Ordered by `glyph_id`.
pub metrics: LazyArray16<'a, VerticalOriginMetrics>,
}
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 {
return None;
}
let default_y = s.read::<i16>()?;
let count = s.read::<u16>()?;
let metrics = s.read_array16::<VerticalOriginMetrics>(count)?;
Some(Table {
default_y,
metrics,
})
}
/// Returns glyph's Y origin.
pub fn glyph_y_origin(&self, glyph_id: GlyphId) -> i16 {
self.metrics.binary_search_by(|m| m.glyph_id.cmp(&glyph_id))
.map(|(_, m)| m.y)
.unwrap_or(self.default_y)
}
}