Change the API of parsing CFF tables to avoid a breaking change (#200)

Author: LaurenzV

src/lib.rs

@@ -1337,7 +1337,9 @@ impl<'a> Face<'a> {
 
             bdat,
             cbdt,
-            cff: raw_tables.cff.and_then(|data| cff::Table::parse(data, head.units_per_em)),
+            cff: raw_tables
+                .cff
+                .and_then(|data| cff::Table::parse_with_upem(data, head.units_per_em)),
             cmap: raw_tables.cmap.and_then(cmap::Table::parse),
             colr,
             ebdt,

src/tables/cff/cff1.rs

@@ -374,8 +374,13 @@ fn parse_char_string(
         local_subrs,
     };
 
-    let transform = (metadata.units_per_em, metadata.matrix());
-    let transform = (transform != (1000, Matrix::default())).then_some(transform);
+    let (upem, transform) = (metadata.units_per_em, metadata.matrix());
+    let transform = if let Some(upem) = upem {
+        ((upem, transform) != (1000, Matrix::default())).then_some((upem, transform))
+    } else {
+        None
+    };
+
     let mut inner_builder = Builder {
         builder,
         bbox: RectF::new(),
@@ -802,7 +807,11 @@ fn parse_sid_metadata<'a>(
     Some(FontKind::SID(metadata))
 }
 
-fn parse_cid_metadata(data: &[u8], top_dict: TopDict, number_of_glyphs: u16) -> Option<FontKind<'_>> {
+fn parse_cid_metadata(
+    data: &[u8],
+    top_dict: TopDict,
+    number_of_glyphs: u16,
+) -> Option<FontKind<'_>> {
     let (charset_offset, fd_array_offset, fd_select_offset) = match (
         top_dict.charset_offset,
         top_dict.fd_array_offset,
@@ -852,12 +861,23 @@ pub struct Table<'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,
+    units_per_em: Option<u16>,
 }
 
 impl<'a> Table<'a> {
     /// Parses a table from raw data.
-    pub fn parse(data: &'a [u8], units_per_em: u16) -> Option<Self> {
+    pub fn parse(data: &'a [u8]) -> Option<Self> {
+        Self::parse_inner(data, None)
+    }
+
+    /// The same as [`Table::parse`], with the difference that it allows you to
+    /// manually pass the units per em of the font, which is needed to properly
+    /// scale certain fonts with a non-identity matrix.
+    pub(crate) fn parse_with_upem(data: &'a [u8], units_per_em: u16) -> Option<Self> {
+        Self::parse_inner(data, Some(units_per_em))
+    }
+
+    fn parse_inner(data: &'a [u8], units_per_em: Option<u16>) -> Option<Self> {
         let mut s = Stream::new(data);
 
         // Parse Header.

tests/tables/cff1.rs

@@ -312,7 +312,7 @@ fn unsupported_version() {
         UInt8(0), // absolute offset
     ]);
 
-    assert!(cff::Table::parse(&data, 1000).is_none());
+    assert!(cff::Table::parse(&data).is_none());
 }
 
 #[test]
@@ -360,7 +360,7 @@ fn non_default_header_size() {
         UInt8(operator::ENDCHAR),
     ]);
 
-    let table = cff::Table::parse(&data, 1000).unwrap();
+    let table = cff::Table::parse(&data).unwrap();
     let mut builder = Builder(String::new());
     let rect = table.outline(GlyphId(0), &mut builder).unwrap();
 
@@ -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, 1000).unwrap();
+            let table = cff::Table::parse(&data).unwrap();
             let mut builder = Builder(String::new());
             let rect = table.outline(GlyphId(0), &mut builder).unwrap();
 
@@ -398,7 +398,7 @@ macro_rules! test_cs_err {
         #[test]
         fn $name() {
             let data = gen_cff(&[], &[], $values);
-            let table = cff::Table::parse(&data, 1000).unwrap();
+            let table = cff::Table::parse(&data).unwrap();
             let mut builder = Builder(String::new());
             let res = table.outline(GlyphId(0), &mut builder);
             assert_eq!(res.unwrap_err(), $err);
@@ -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, 1000).unwrap();
+    let table = cff::Table::parse(&data).unwrap();
     let mut builder = Builder(String::new());
     assert!(table.outline(GlyphId(0), &mut builder).is_err());
 }
@@ -800,7 +800,7 @@ fn endchar_in_subr_with_extra_data_1() {
         ]
     );
 
-    let table = cff::Table::parse(&data, 1000).unwrap();
+    let table = cff::Table::parse(&data).unwrap();
     let mut builder = Builder(String::new());
     let res = table.outline(GlyphId(0), &mut builder);
     assert_eq!(res.unwrap_err(), CFFError::DataAfterEndChar);
@@ -827,7 +827,7 @@ fn endchar_in_subr_with_extra_data_2() {
         ]
     );
 
-    let table = cff::Table::parse(&data, 1000).unwrap();
+    let table = cff::Table::parse(&data).unwrap();
     let mut builder = Builder(String::new());
     let res = table.outline(GlyphId(0), &mut builder);
     assert_eq!(res.unwrap_err(), CFFError::DataAfterEndChar);
@@ -854,7 +854,7 @@ fn subr_without_return() {
         ]
     );
 
-    let table = cff::Table::parse(&data, 1000).unwrap();
+    let table = cff::Table::parse(&data).unwrap();
     let mut builder = Builder(String::new());
     let res = table.outline(GlyphId(0), &mut builder);
     assert_eq!(res.unwrap_err(), CFFError::DataAfterEndChar);
@@ -876,7 +876,7 @@ fn recursive_local_subr() {
         ]
     );
 
-    let table = cff::Table::parse(&data, 1000).unwrap();
+    let table = cff::Table::parse(&data).unwrap();
     let mut builder = Builder(String::new());
     let res = table.outline(GlyphId(0), &mut builder);
     assert_eq!(res.unwrap_err(), CFFError::NestingLimitReached);
@@ -898,7 +898,7 @@ fn recursive_global_subr() {
         ]
     );
 
-    let table = cff::Table::parse(&data, 1000).unwrap();
+    let table = cff::Table::parse(&data).unwrap();
     let mut builder = Builder(String::new());
     let res = table.outline(GlyphId(0), &mut builder);
     assert_eq!(res.unwrap_err(), CFFError::NestingLimitReached);
@@ -923,7 +923,7 @@ fn recursive_mixed_subr() {
         ]
     );
 
-    let table = cff::Table::parse(&data, 1000).unwrap();
+    let table = cff::Table::parse(&data).unwrap();
     let mut builder = Builder(String::new());
     let res = table.outline(GlyphId(0), &mut builder);
     assert_eq!(res.unwrap_err(), CFFError::NestingLimitReached);
@@ -952,7 +952,7 @@ fn zero_char_string_offset() {
         UInt8(top_dict_operator::CHAR_STRINGS_OFFSET as u8),
     ]);
 
-    assert!(cff::Table::parse(&data, 1000).is_none());
+    assert!(cff::Table::parse(&data).is_none());
 }
 
 #[test]
@@ -978,7 +978,7 @@ fn invalid_char_string_offset() {
         UInt8(top_dict_operator::CHAR_STRINGS_OFFSET as u8),
     ]);
 
-    assert!(cff::Table::parse(&data, 1000).is_none());
+    assert!(cff::Table::parse(&data).is_none());
 }
 
 // TODO: return from main