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LibGfx/OpenType: Read "hhea" table using a C++ struct

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This commit is contained in:
Andreas Kling 2022-12-19 13:36:09 +01:00
parent 61be11960b
commit d201acf102
2 changed files with 27 additions and 15 deletions
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12
Userland/Libraries/LibGfx/Font/OpenType/Font.cpp
View file

@ -107,7 +107,7 @@ IndexToLocFormat Head::index_to_loc_format() const
Optional<Hhea> Hhea::from_slice(ReadonlyBytes slice) Optional<Hhea> Hhea::from_slice(ReadonlyBytes slice)
{ {
if (slice.size() < (size_t)Sizes::Table) { if (slice.size() < sizeof(HorizontalHeaderTable)) {
return {}; return {};
} }
return Hhea(slice); return Hhea(slice);
@ -115,27 +115,27 @@ Optional<Hhea> Hhea::from_slice(ReadonlyBytes slice)
i16 Hhea::ascender() const i16 Hhea::ascender() const
{ {
return be_i16(m_slice.offset_pointer((u32)Offsets::Ascender)); return header().ascender;
} }
i16 Hhea::descender() const i16 Hhea::descender() const
{ {
return be_i16(m_slice.offset_pointer((u32)Offsets::Descender)); return header().descender;
} }
i16 Hhea::line_gap() const i16 Hhea::line_gap() const
{ {
return be_i16(m_slice.offset_pointer((u32)Offsets::LineGap)); return header().line_gap;
} }
u16 Hhea::advance_width_max() const u16 Hhea::advance_width_max() const
{ {
return be_u16(m_slice.offset_pointer((u32)Offsets::AdvanceWidthMax)); return header().advance_width_max;
} }
u16 Hhea::number_of_h_metrics() const u16 Hhea::number_of_h_metrics() const
{ {
return be_u16(m_slice.offset_pointer((u32)Offsets::NumberOfHMetrics)); return header().number_of_h_metrics;
} }
Optional<Maxp> Maxp::from_slice(ReadonlyBytes slice) Optional<Maxp> Maxp::from_slice(ReadonlyBytes slice)

30
Userland/Libraries/LibGfx/Font/OpenType/Tables.h
View file

@ -28,6 +28,9 @@ struct LongDateTime {
BigEndian<u64> value; BigEndian<u64> value;
}; };
using FWord = BigEndian<i16>;
using UFWord = 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
class Head { class Head {
@ -86,17 +89,26 @@ public:
u16 number_of_h_metrics() const; u16 number_of_h_metrics() const;
private: private:
enum class Offsets { struct HorizontalHeaderTable {
Ascender = 4, BigEndian<u16> major_version;
Descender = 6, BigEndian<u16> minor_version;
LineGap = 8, FWord ascender;
AdvanceWidthMax = 10, FWord descender;
NumberOfHMetrics = 34, FWord line_gap;
}; UFWord advance_width_max;
enum class Sizes { FWord min_left_side_bearing;
Table = 36, FWord min_right_side_bearing;
FWord x_max_extent;
BigEndian<i16> caret_slope_rise;
BigEndian<i16> caret_slope_run;
BigEndian<i16> caret_offset;
BigEndian<i16> reserved[4];
BigEndian<i16> metric_data_format;
BigEndian<u16> number_of_h_metrics;
}; };
HorizontalHeaderTable const& header() const { return *bit_cast<HorizontalHeaderTable const*>(m_slice.data()); }
Hhea(ReadonlyBytes slice) Hhea(ReadonlyBytes slice)
: m_slice(slice) : m_slice(slice)
{ {