From 9bccb8c8d724be7fde078246c445b9326b8011d4 Mon Sep 17 00:00:00 2001
From: Nico Weber <thakis@chromium.org>
Date: Mon, 5 Feb 2024 21:30:45 -0500
Subject: [PATCH] LibPDF: Make CFF::parse_charset() return SIDs

...and do string expansion at the call site.

CID-keyed fonts treat the charset as CIDs instead of as SIDs,
so having access to the SIDs in numberic form will be useful
when we implement support for CID-keyed CFF fonts.

No behavior change.
---
 Userland/Libraries/LibPDF/Fonts/CFF.cpp | 17 ++++++++++-------
 Userland/Libraries/LibPDF/Fonts/CFF.h   |  2 +-
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/Userland/Libraries/LibPDF/Fonts/CFF.cpp b/Userland/Libraries/LibPDF/Fonts/CFF.cpp
index 71985fa7a5..a58ce77bc1 100644
--- a/Userland/Libraries/LibPDF/Fonts/CFF.cpp
+++ b/Userland/Libraries/LibPDF/Fonts/CFF.cpp
@@ -267,10 +267,13 @@ PDFErrorOr<NonnullRefPtr<CFF>> CFF::create(ReadonlyBytes const& cff_bytes, RefPt
         for (SID sid : s_predefined_charset_expert_subset)
             TRY(charset_names.try_append(resolve_sid(sid, strings)));
         break;
-    default:
-        charset_names = TRY(parse_charset(Reader { cff_bytes.slice(charset_offset) }, glyphs.size(), strings));
+    default: {
+        auto charset = TRY(parse_charset(Reader { cff_bytes.slice(charset_offset) }, glyphs.size()));
+        for (SID sid : charset)
+            TRY(charset_names.try_append(resolve_sid(sid, strings)));
         break;
     }
+    }
 
     // Adjust glyphs' widths as they are deltas from nominalWidthX
     for (auto& glyph : glyphs) {
@@ -734,17 +737,17 @@ DeprecatedFlyString CFF::resolve_sid(SID sid, Vector<StringView> const& strings)
     return DeprecatedFlyString("space");
 }
 
-PDFErrorOr<Vector<DeprecatedFlyString>> CFF::parse_charset(Reader&& reader, size_t glyph_count, Vector<StringView> const& strings)
+PDFErrorOr<Vector<CFF::SID>> CFF::parse_charset(Reader&& reader, size_t glyph_count)
 {
     // CFF spec, "13 Charsets"
-    Vector<DeprecatedFlyString> names;
+    Vector<SID> names;
     auto format = TRY(reader.try_read<Card8>());
     if (format == 0) {
         // CFF spec, "Table 17 Format 0"
         dbgln_if(CFF_DEBUG, "CFF charset format 0");
         for (size_t i = 0; i < glyph_count - 1; i++) {
             SID sid = TRY(reader.try_read<BigEndian<SID>>());
-            TRY(names.try_append(resolve_sid(sid, strings)));
+            TRY(names.try_append(sid));
         }
     } else if (format == 1) {
         // CFF spec, "Table 18 Format 1"
@@ -754,7 +757,7 @@ PDFErrorOr<Vector<DeprecatedFlyString>> CFF::parse_charset(Reader&& reader, size
             auto first_sid = TRY(reader.try_read<BigEndian<SID>>());
             int left = TRY(reader.try_read<Card8>());
             for (SID sid = first_sid; left >= 0 && names.size() < glyph_count - 1; left--, sid++)
-                TRY(names.try_append(resolve_sid(sid, strings)));
+                TRY(names.try_append(sid));
         }
     } else if (format == 2) {
         // CFF spec, "Table 20 Format 2"
@@ -765,7 +768,7 @@ PDFErrorOr<Vector<DeprecatedFlyString>> CFF::parse_charset(Reader&& reader, size
             auto first_sid = TRY(reader.try_read<BigEndian<SID>>());
             int left = TRY(reader.try_read<BigEndian<Card16>>());
             for (SID sid = first_sid; left >= 0 && names.size() < glyph_count - 1; left--, sid++)
-                TRY(names.try_append(resolve_sid(sid, strings)));
+                TRY(names.try_append(sid));
         }
     } else {
         dbgln("CFF: Unknown charset format {}", format);
diff --git a/Userland/Libraries/LibPDF/Fonts/CFF.h b/Userland/Libraries/LibPDF/Fonts/CFF.h
index 50ff7fb4eb..3b160f80f9 100644
--- a/Userland/Libraries/LibPDF/Fonts/CFF.h
+++ b/Userland/Libraries/LibPDF/Fonts/CFF.h
@@ -97,7 +97,7 @@ public:
     static PDFErrorOr<Vector<CFF::Glyph>> parse_charstrings(Reader&&, Vector<ByteBuffer> const& local_subroutines, Vector<ByteBuffer> const& global_subroutines);
 
     static DeprecatedFlyString resolve_sid(SID, Vector<StringView> const&);
-    static PDFErrorOr<Vector<DeprecatedFlyString>> parse_charset(Reader&&, size_t, Vector<StringView> const&);
+    static PDFErrorOr<Vector<SID>> parse_charset(Reader&&, size_t);
     static PDFErrorOr<Vector<u8>> parse_encoding(Reader&&, HashMap<Card8, SID>& supplemental);
 };