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LibGfx/OpenType: Clean up "name" table reading

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Use a C++ struct to read out the header, and make the rest of the code
more idiomatic.
This commit is contained in:
Andreas Kling 2022-12-19 20:37:15 +01:00
parent 5d8feab131
commit afba67f3a2
2 changed files with 44 additions and 20 deletions
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33
Userland/Libraries/LibGfx/Font/OpenType/Font.cpp
View file

@ -297,14 +297,14 @@ Optional<i16> Kern::read_glyph_kerning_format0(ReadonlyBytes slice, u16 left_gly
DeprecatedString Name::string_for_id(NameId id) const DeprecatedString Name::string_for_id(NameId id) const
{ {
auto num_entries = be_u16(m_slice.offset_pointer(2)); auto const count = header().count;
auto string_offset = be_u16(m_slice.offset_pointer(4)); auto const storage_offset = header().storage_offset;
Vector<int> valid_ids; Vector<int> valid_ids;
for (int i = 0; i < num_entries; ++i) { for (size_t i = 0; i < count; ++i) {
auto this_id = be_u16(m_slice.offset_pointer(6 + i * 12 + 6)); auto this_id = header().name_record[i].name_id;
if (this_id == (u16)id) if (this_id == to_underlying(id))
valid_ids.append(i); valid_ids.append(i);
} }
@ -313,23 +313,26 @@ DeprecatedString Name::string_for_id(NameId id) const
auto it = valid_ids.find_if([this](auto const& i) { auto it = valid_ids.find_if([this](auto const& i) {
// check if font has naming table for en-US language id // check if font has naming table for en-US language id
auto platform = be_u16(m_slice.offset_pointer(6 + i * 12 + 0)); auto const& name_record = header().name_record[i];
auto language_id = be_u16(m_slice.offset_pointer(6 + i * 12 + 4)); auto const platform_id = name_record.platform_id;
return (platform == (u16)Platform::Macintosh && language_id == (u16)MacintoshLanguage::English) auto const language_id = name_record.language_id;
|| (platform == (u16)Platform::Windows && language_id == (u16)WindowsLanguage::EnglishUnitedStates); return (platform_id == to_underlying(Platform::Macintosh) && language_id == to_underlying(MacintoshLanguage::English))
|| (platform_id == to_underlying(Platform::Windows) && language_id == to_underlying(WindowsLanguage::EnglishUnitedStates));
}); });
auto i = it != valid_ids.end() ? *it : valid_ids.first(); auto i = it != valid_ids.end() ? *it : valid_ids.first();
auto platform = be_u16(m_slice.offset_pointer(6 + i * 12 + 0)); auto const& name_record = header().name_record[i];
auto length = be_u16(m_slice.offset_pointer(6 + i * 12 + 8));
auto offset = be_u16(m_slice.offset_pointer(6 + i * 12 + 10));
if (platform == (u16)Platform::Windows) { auto const platform_id = name_record.platform_id;
auto const length = name_record.length;
auto const offset = name_record.string_offset;
if (platform_id == to_underlying(Platform::Windows)) {
static auto& decoder = *TextCodec::decoder_for("utf-16be"); static auto& decoder = *TextCodec::decoder_for("utf-16be");
return decoder.to_utf8(StringView { (char const*)m_slice.offset_pointer(string_offset + offset), length }); return decoder.to_utf8(StringView { (char const*)m_slice.offset_pointer(storage_offset + offset), length });
} }
return DeprecatedString((char const*)m_slice.offset_pointer(string_offset + offset), length); return DeprecatedString((char const*)m_slice.offset_pointer(storage_offset + offset), length);
} }
GlyphHorizontalMetrics Hmtx::get_glyph_horizontal_metrics(u32 glyph_id) const GlyphHorizontalMetrics Hmtx::get_glyph_horizontal_metrics(u32 glyph_id) const

31
Userland/Libraries/LibGfx/Font/OpenType/Tables.h
View file

@ -36,6 +36,7 @@ struct Version16Dot16 {
using FWord = BigEndian<i16>; using FWord = BigEndian<i16>;
using UFWord = BigEndian<u16>; using UFWord = BigEndian<u16>;
using Tag = BigEndian<u32>; using Tag = BigEndian<u32>;
using Offset16 = BigEndian<u16>;
// https://learn.microsoft.com/en-us/typography/opentype/spec/head // https://learn.microsoft.com/en-us/typography/opentype/spec/head
// head: Font Header Table // head: Font Header Table
@ -253,15 +254,15 @@ private:
// name: Naming Table // name: Naming Table
class Name { class Name {
public: public:
enum class Platform { enum class Platform : u16 {
Unicode = 0, Unicode = 0,
Macintosh = 1, Macintosh = 1,
Windows = 3, Windows = 3,
}; };
enum class MacintoshLanguage { enum class MacintoshLanguage : u16 {
English = 0, English = 0,
}; };
enum class WindowsLanguage { enum class WindowsLanguage : u16 {
EnglishUnitedStates = 0x0409, EnglishUnitedStates = 0x0409,
}; };
static Optional<Name> from_slice(ReadonlyBytes); static Optional<Name> from_slice(ReadonlyBytes);
@ -272,7 +273,27 @@ public:
DeprecatedString typographic_subfamily_name() const { return string_for_id(NameId::TypographicSubfamilyName); } DeprecatedString typographic_subfamily_name() const { return string_for_id(NameId::TypographicSubfamilyName); }
private: private:
enum class NameId { // https://learn.microsoft.com/en-us/typography/opentype/spec/name#name-records
struct NameRecord {
BigEndian<u16> platform_id;
BigEndian<u16> encoding_id;
BigEndian<u16> language_id;
BigEndian<u16> name_id;
BigEndian<u16> length;
Offset16 string_offset;
};
// https://learn.microsoft.com/en-us/typography/opentype/spec/name#naming-table-version-0
struct NamingTableVersion0 {
BigEndian<u16> version;
BigEndian<u16> count;
Offset16 storage_offset;
NameRecord name_record[0];
};
NamingTableVersion0 const& header() const { return *bit_cast<NamingTableVersion0 const*>(m_slice.data()); }
enum class NameId : u16 {
Copyright = 0, Copyright = 0,
FamilyName = 1, FamilyName = 1,
SubfamilyName = 2, SubfamilyName = 2,
@ -293,7 +314,7 @@ private:
{ {
} }
DeprecatedString string_for_id(NameId id) const; DeprecatedString string_for_id(NameId) const;
ReadonlyBytes m_slice; ReadonlyBytes m_slice;
}; };