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Transform CFF glyphs by their matrix #198

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Merged
LaurenzV merged 1 commit into from
Sep 9, 2025
Merged

Transform CFF glyphs by their matrix #198

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2 changes: 1 addition & 1 deletion src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1337,7 +1337,7 @@ impl<'a> Face<'a> {

bdat,
cbdt,
cff: raw_tables.cff.and_then(cff::Table::parse),
cff: raw_tables.cff.and_then(|data| cff::Table::parse(data, head.units_per_em)),
cmap: raw_tables.cmap.and_then(cmap::Table::parse),
colr,
ebdt,
Expand Down
12 changes: 10 additions & 2 deletions src/tables/cff/cff1.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -122,7 +122,7 @@ pub(crate) struct CIDMetadata<'a> {

/// An affine transformation matrix.
#[allow(missing_docs)]
#[derive(Clone, Copy, Debug)]
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct Matrix {
pub sx: f32,
pub ky: f32,
Expand Down Expand Up @@ -374,9 +374,12 @@ fn parse_char_string(
local_subrs,
};

let transform = (metadata.units_per_em, metadata.matrix());
let transform = (transform != (1000, Matrix::default())).then_some(transform);
let mut inner_builder = Builder {
builder,
bbox: RectF::new(),
transform,
};

let stack = ArgumentsStack {
Expand Down Expand Up @@ -846,11 +849,15 @@ pub struct Table<'a> {
matrix: Matrix,
char_strings: Index<'a>,
kind: FontKind<'a>,

// Copy of Face::units_per_em().
// Required to do glyph outlining, since coordinates must be scaled up by this before applying the `matrix`.
units_per_em: u16,
}

impl<'a> Table<'a> {
/// Parses a table from raw data.
pub fn parse(data: &'a [u8]) -> Option<Self> {
pub fn parse(data: &'a [u8], units_per_em: u16) -> Option<Self> {
let mut s = Stream::new(data);

// Parse Header.
Expand Down Expand Up @@ -930,6 +937,7 @@ impl<'a> Table<'a> {
matrix,
char_strings,
kind,
units_per_em,
})
}

Expand Down
1 change: 1 addition & 0 deletions src/tables/cff/cff2.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -250,6 +250,7 @@ fn parse_char_string(
let mut inner_builder = Builder {
builder,
bbox: RectF::new(),
transform: None,
};

let stack = ArgumentsStack {
Expand Down
21 changes: 21 additions & 0 deletions src/tables/cff/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -45,23 +45,29 @@ pub enum CFFError {
pub(crate) struct Builder<'a> {
builder: &'a mut dyn OutlineBuilder,
bbox: RectF,
transform: Option<(u16, cff1::Matrix)>,
}

impl<'a> Builder<'a> {
#[inline]
fn move_to(&mut self, x: f32, y: f32) {
let (x, y) = self.transform(x, y);
self.bbox.extend_by(x, y);
self.builder.move_to(x, y);
}

#[inline]
fn line_to(&mut self, x: f32, y: f32) {
let (x, y) = self.transform(x, y);
self.bbox.extend_by(x, y);
self.builder.line_to(x, y);
}

#[inline]
fn curve_to(&mut self, x1: f32, y1: f32, x2: f32, y2: f32, x: f32, y: f32) {
let (x1, y1) = self.transform(x1, y1);
let (x2, y2) = self.transform(x2, y2);
let (x, y) = self.transform(x, y);
self.bbox.extend_by(x1, y1);
self.bbox.extend_by(x2, y2);
self.bbox.extend_by(x, y);
Expand All @@ -72,6 +78,21 @@ impl<'a> Builder<'a> {
fn close(&mut self) {
self.builder.close();
}

#[inline]
fn transform(&self, x: f32, y: f32) -> (f32, f32) {
let (units_per_em, matrix) = if let Some(transform) = self.transform {
transform
} else {
return (x, y);
};
let (mut tx, mut ty) = (x, y);
tx = tx * matrix.sx + ty * matrix.kx + matrix.tx;
ty = tx * matrix.ky + ty * matrix.sy + matrix.ty;
tx *= units_per_em as f32;
ty *= units_per_em as f32;
(tx, ty)
}
}

/// A type-safe wrapper for string ID.
Expand Down
26 changes: 13 additions & 13 deletions tests/tables/cff1.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -312,7 +312,7 @@ fn unsupported_version() {
UInt8(0), // absolute offset
]);

assert!(cff::Table::parse(&data).is_none());
assert!(cff::Table::parse(&data, 1000).is_none());
}

#[test]
Expand Down Expand Up @@ -360,7 +360,7 @@ fn non_default_header_size() {
UInt8(operator::ENDCHAR),
]);

let table = cff::Table::parse(&data).unwrap();
let table = cff::Table::parse(&data, 1000).unwrap();
let mut builder = Builder(String::new());
let rect = table.outline(GlyphId(0), &mut builder).unwrap();

Expand All @@ -377,7 +377,7 @@ macro_rules! test_cs_with_subrs {
#[test]
fn $name() {
let data = gen_cff($glob, $loc, $values);
let table = cff::Table::parse(&data).unwrap();
let table = cff::Table::parse(&data, 1000).unwrap();
let mut builder = Builder(String::new());
let rect = table.outline(GlyphId(0), &mut builder).unwrap();

Expand All @@ -398,7 +398,7 @@ macro_rules! test_cs_err {
#[test]
fn $name() {
let data = gen_cff(&[], &[], $values);
let table = cff::Table::parse(&data).unwrap();
let table = cff::Table::parse(&data, 1000).unwrap();
let mut builder = Builder(String::new());
let res = table.outline(GlyphId(0), &mut builder);
assert_eq!(res.unwrap_err(), $err);
Expand Down Expand Up @@ -575,7 +575,7 @@ test_cs!(vv_curve_to_with_x, &[
#[test]
fn only_endchar() {
let data = gen_cff(&[], &[], &[UInt8(operator::ENDCHAR)]);
let table = cff::Table::parse(&data).unwrap();
let table = cff::Table::parse(&data, 1000).unwrap();
let mut builder = Builder(String::new());
assert!(table.outline(GlyphId(0), &mut builder).is_err());
}
Expand Down Expand Up @@ -800,7 +800,7 @@ fn endchar_in_subr_with_extra_data_1() {
]
);

let table = cff::Table::parse(&data).unwrap();
let table = cff::Table::parse(&data, 1000).unwrap();
let mut builder = Builder(String::new());
let res = table.outline(GlyphId(0), &mut builder);
assert_eq!(res.unwrap_err(), CFFError::DataAfterEndChar);
Expand All @@ -827,7 +827,7 @@ fn endchar_in_subr_with_extra_data_2() {
]
);

let table = cff::Table::parse(&data).unwrap();
let table = cff::Table::parse(&data, 1000).unwrap();
let mut builder = Builder(String::new());
let res = table.outline(GlyphId(0), &mut builder);
assert_eq!(res.unwrap_err(), CFFError::DataAfterEndChar);
Expand All @@ -854,7 +854,7 @@ fn subr_without_return() {
]
);

let table = cff::Table::parse(&data).unwrap();
let table = cff::Table::parse(&data, 1000).unwrap();
let mut builder = Builder(String::new());
let res = table.outline(GlyphId(0), &mut builder);
assert_eq!(res.unwrap_err(), CFFError::DataAfterEndChar);
Expand All @@ -876,7 +876,7 @@ fn recursive_local_subr() {
]
);

let table = cff::Table::parse(&data).unwrap();
let table = cff::Table::parse(&data, 1000).unwrap();
let mut builder = Builder(String::new());
let res = table.outline(GlyphId(0), &mut builder);
assert_eq!(res.unwrap_err(), CFFError::NestingLimitReached);
Expand All @@ -898,7 +898,7 @@ fn recursive_global_subr() {
]
);

let table = cff::Table::parse(&data).unwrap();
let table = cff::Table::parse(&data, 1000).unwrap();
let mut builder = Builder(String::new());
let res = table.outline(GlyphId(0), &mut builder);
assert_eq!(res.unwrap_err(), CFFError::NestingLimitReached);
Expand All @@ -923,7 +923,7 @@ fn recursive_mixed_subr() {
]
);

let table = cff::Table::parse(&data).unwrap();
let table = cff::Table::parse(&data, 1000).unwrap();
let mut builder = Builder(String::new());
let res = table.outline(GlyphId(0), &mut builder);
assert_eq!(res.unwrap_err(), CFFError::NestingLimitReached);
Expand Down Expand Up @@ -952,7 +952,7 @@ fn zero_char_string_offset() {
UInt8(top_dict_operator::CHAR_STRINGS_OFFSET as u8),
]);

assert!(cff::Table::parse(&data).is_none());
assert!(cff::Table::parse(&data, 1000).is_none());
}

#[test]
Expand All @@ -978,7 +978,7 @@ fn invalid_char_string_offset() {
UInt8(top_dict_operator::CHAR_STRINGS_OFFSET as u8),
]);

assert!(cff::Table::parse(&data).is_none());
assert!(cff::Table::parse(&data, 1000).is_none());
}

// TODO: return from main
Expand Down
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