Add morx table.

CHANGELOG.md

@@ -7,7 +7,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ## [Unreleased]
 ### Added
 - `apple-layout` build feature.
-- `ankr`, `feat` and `trak` tables.
+- `ankr`, `feat`, `morx` and `trak` tables.
 
 ## [0.14.0] - 2021-12-28
 ### Changed

Cargo.toml

@@ -20,7 +20,7 @@ std = []
 variable-fonts = []
 # Enables GDEF, GPOS and GSUB tables.
 opentype-layout = []
-# Enables feat, trak tables.
+# Enables ankr, feat, morx and trak tables.
 apple-layout = []
 # Enables glyph name query via `Face::glyph_name`.
 # TrueType fonts do not store default glyph names, to reduce file size,

README.md

@@ -83,6 +83,7 @@ There are roughly three types of TrueType tables:
 | `HVAR` table      | ✓                      | ✓                   |                                |
 | `kern` table      | ~ (no AAT 1)           | ~ (only 0)          | ~ (only 0)                     |
 | `maxp` table      | ✓                      | ✓                   | ✓                              |
+| `morx` table      | ✓                      |                     |                                |
 | `MVAR` table      | ✓                      | ✓                   |                                |
 | `name` table      | ✓                      | ✓                   |                                |
 | `OS/2` table      | ✓                      | ✓                   |                                |

src/aat.rs

@@ -7,7 +7,120 @@ related types.
 use core::num::NonZeroU16;
 
 use crate::GlyphId;
-use crate::parser::{Stream, FromData, LazyArray16};
+use crate::parser::{Stream, FromData, LazyArray16, Offset, Offset32, NumFrom};
+
+/// Predefined classes.
+///
+/// Search for _Class Code_ in [Apple Advanced Typography Font Tables](
+/// https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6Tables.html).
+pub mod class {
+    #![allow(missing_docs)]
+    pub const END_OF_TEXT: u16 = 0;
+    pub const OUT_OF_BOUNDS: u16 = 1;
+    pub const DELETED_GLYPH: u16 = 2;
+}
+
+/// An [Extended State Table](ExtendedStateTable) entry.
+#[derive(Clone, Copy, Debug)]
+pub struct ExtendedStateEntry<T: FromData> {
+    /// A new state.
+    pub new_state: u16,
+    /// Entry flags.
+    pub flags: u16,
+    /// Additional data.
+    ///
+    /// Use `()` if no data expected.
+    pub extra: T,
+}
+
+impl<T: FromData> FromData for ExtendedStateEntry<T> {
+    const SIZE: usize = 4 + T::SIZE;
+
+    #[inline]
+    fn parse(data: &[u8]) -> Option<Self> {
+        let mut s = Stream::new(data);
+        Some(ExtendedStateEntry {
+            new_state: s.read::<u16>()?,
+            flags: s.read::<u16>()?,
+            extra: s.read::<T>()?,
+        })
+    }
+}
+
+/// An [Extended State Table](
+/// https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6Tables.html).
+///
+/// Also called `STXHeader`.
+///
+/// Currently used by `kerx` and `morx` tables.
+#[derive(Clone)]
+pub struct ExtendedStateTable<'a, T> {
+    number_of_classes: u32,
+    lookup: Lookup<'a>,
+    state_array: &'a [u8],
+    entry_table: &'a [u8],
+    entry_type: core::marker::PhantomData<T>,
+}
+
+impl<'a, T: FromData> ExtendedStateTable<'a, T> {
+    // TODO: make private
+    /// Parses an Extended State Table from a stream.
+    ///
+    /// `number_of_glyphs` is from the `maxp` table.
+    pub fn parse(number_of_glyphs: NonZeroU16, s: &mut Stream<'a>) -> Option<Self> {
+        let data = s.tail()?;
+
+        let number_of_classes = s.read::<u32>()?;
+        // Note that offsets are not from the subtable start,
+        // but from subtable start + `header_size`.
+        // So there is not need to subtract the `header_size`.
+        let lookup_table_offset = s.read::<Offset32>()?.to_usize();
+        let state_array_offset = s.read::<Offset32>()?.to_usize();
+        let entry_table_offset = s.read::<Offset32>()?.to_usize();
+
+        Some(ExtendedStateTable {
+            number_of_classes,
+            lookup: Lookup::parse(number_of_glyphs, data.get(lookup_table_offset..)?)?,
+            // We don't know the actual data size and it's kinda expensive to calculate.
+            // So we are simply storing all the data past the offset.
+            // Despite the fact that they may overlap.
+            state_array: data.get(state_array_offset..)?,
+            entry_table: data.get(entry_table_offset..)?,
+            entry_type: core::marker::PhantomData,
+        })
+    }
+
+    /// Returns a glyph class.
+    #[inline]
+    pub fn class(&self, glyph_id: GlyphId) -> Option<u16> {
+        if glyph_id.0 == 0xFFFF {
+            return Some(class::DELETED_GLYPH);
+        }
+
+        self.lookup.value(glyph_id)
+    }
+
+    /// Returns a class entry.
+    #[inline]
+    pub fn entry(&self, state: u16, mut class: u16) -> Option<ExtendedStateEntry<T>> {
+        if u32::from(class) >= self.number_of_classes {
+            class = class::OUT_OF_BOUNDS;
+        }
+
+        let state_idx =
+            usize::from(state) * usize::num_from(self.number_of_classes) + usize::from(class);
+
+        let entry_idx: u16 = Stream::read_at(self.state_array, state_idx * u16::SIZE)?;
+        Stream::read_at(self.entry_table, usize::from(entry_idx) * ExtendedStateEntry::<T>::SIZE)
+    }
+}
+
+impl<T> core::fmt::Debug for ExtendedStateTable<'_, T> {
+    fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
+        write!(f, "ExtendedStateTable {{ ... }}")
+    }
+}
+
 
 /// A [lookup table](
 /// https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6Tables.html).

src/lib.rs

@@ -69,7 +69,7 @@ pub use tables::CFFError;
 pub use tables::{cmap, kern, sbix, maxp, hmtx, name, os2, loca, svg, vorg, post, head, hhea, glyf};
 pub use tables::{cff1 as cff, vhea, cbdt, cblc};
 #[cfg(feature = "opentype-layout")] pub use tables::{gdef, gpos, gsub};
-#[cfg(feature = "apple-layout")] pub use tables::{ankr, feat, trak};
+#[cfg(feature = "apple-layout")] pub use tables::{ankr, feat, morx, trak};
 #[cfg(feature = "variable-fonts")] pub use tables::{cff2, avar, fvar, gvar, hvar, mvar};
 
 #[cfg(feature = "opentype-layout")]
@@ -572,6 +572,7 @@ pub struct RawFaceTables<'a> {
 
     #[cfg(feature = "apple-layout")] pub ankr: Option<&'a [u8]>,
     #[cfg(feature = "apple-layout")] pub feat: Option<&'a [u8]>,
+    #[cfg(feature = "apple-layout")] pub morx: Option<&'a [u8]>,
     #[cfg(feature = "apple-layout")] pub trak: Option<&'a [u8]>,
 
     #[cfg(feature = "variable-fonts")] pub avar: Option<&'a [u8]>,
@@ -620,6 +621,7 @@ pub struct FaceTables<'a> {
 
     #[cfg(feature = "apple-layout")] pub ankr: Option<ankr::Table<'a>>,
     #[cfg(feature = "apple-layout")] pub feat: Option<feat::Table<'a>>,
+    #[cfg(feature = "apple-layout")] pub morx: Option<morx::Table<'a>>,
     #[cfg(feature = "apple-layout")] pub trak: Option<trak::Table<'a>>,
 
     #[cfg(feature = "variable-fonts")] pub avar: Option<avar::Table<'a>>,
@@ -773,6 +775,8 @@ impl<'a> Face<'a> {
                 b"kern" => tables.kern = table_data,
                 b"loca" => tables.loca = table_data,
                 b"maxp" => tables.maxp = table_data.unwrap_or_default(),
+                #[cfg(feature = "apple-layout")]
+                b"morx" => tables.morx = table_data,
                 b"name" => tables.name = table_data,
                 b"post" => tables.post = table_data,
                 b"sbix" => tables.sbix = table_data,
@@ -866,6 +870,8 @@ impl<'a> Face<'a> {
             #[cfg(feature = "apple-layout")] ankr: raw_tables.ankr
                 .and_then(|data| ankr::Table::parse(maxp.number_of_glyphs, data)),
             #[cfg(feature = "apple-layout")] feat: raw_tables.feat.and_then(feat::Table::parse),
+            #[cfg(feature = "apple-layout")] morx: raw_tables.morx
+                .and_then(|data| morx::Table::parse(maxp.number_of_glyphs, data)),
             #[cfg(feature = "apple-layout")] trak: raw_tables.trak.and_then(trak::Table::parse),
 
             #[cfg(feature = "variable-fonts")] avar: raw_tables.avar.and_then(avar::Table::parse),

src/tables/mod.rs

@@ -23,6 +23,7 @@ pub mod vorg;
 
 #[cfg(feature = "apple-layout")] pub mod ankr;
 #[cfg(feature = "apple-layout")] pub mod feat;
+#[cfg(feature = "apple-layout")] pub mod morx;
 #[cfg(feature = "apple-layout")] pub mod trak;
 
 #[cfg(feature = "variable-fonts")] pub mod avar;