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LibGfx/OpenType: Clean up "htmx" table reading

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Use a C++ struct to read out the LongHorMetrics, and make the rest of
the code more idiomatic.
This commit is contained in:
Andreas Kling 2022-12-19 15:03:03 +01:00
parent f04a878e55
commit e6551e685d
2 changed files with 11 additions and 14 deletions
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19
Userland/Libraries/LibGfx/Font/OpenType/Font.cpp
View file

@ -153,7 +153,7 @@ u16 Maxp::num_glyphs() const
Optional<Hmtx> Hmtx::from_slice(ReadonlyBytes slice, u32 num_glyphs, u32 number_of_h_metrics)
{
if (slice.size() < number_of_h_metrics * (u32)Sizes::LongHorMetric + (num_glyphs - number_of_h_metrics) * (u32)Sizes::LeftSideBearing) {
if (slice.size() < number_of_h_metrics * sizeof(LongHorMetric) + (num_glyphs - number_of_h_metrics) * sizeof(u16)) {
return {};
}
return Hmtx(slice, num_glyphs, number_of_h_metrics);
@ -335,21 +335,18 @@ DeprecatedString Name::string_for_id(NameId id) const
GlyphHorizontalMetrics Hmtx::get_glyph_horizontal_metrics(u32 glyph_id) const
{
VERIFY(glyph_id < m_num_glyphs);
auto const* long_hor_metrics = bit_cast<LongHorMetric const*>(m_slice.data());
if (glyph_id < m_number_of_h_metrics) {
auto offset = glyph_id * (u32)Sizes::LongHorMetric;
u16 advance_width = be_u16(m_slice.offset_pointer(offset));
i16 left_side_bearing = be_i16(m_slice.offset_pointer(offset + 2));
return GlyphHorizontalMetrics {
.advance_width = advance_width,
.left_side_bearing = left_side_bearing,
.advance_width = static_cast<u16>(long_hor_metrics[glyph_id].advance_width),
.left_side_bearing = static_cast<i16>(long_hor_metrics[glyph_id].lsb),
};
}
auto offset = m_number_of_h_metrics * (u32)Sizes::LongHorMetric + (glyph_id - m_number_of_h_metrics) * (u32)Sizes::LeftSideBearing;
u16 advance_width = be_u16(m_slice.offset_pointer((m_number_of_h_metrics - 1) * (u32)Sizes::LongHorMetric));
i16 left_side_bearing = be_i16(m_slice.offset_pointer(offset));
auto const* left_side_bearings = bit_cast<BigEndian<u16> const*>(m_slice.offset_pointer(m_number_of_h_metrics * sizeof(LongHorMetric)));
return GlyphHorizontalMetrics {
.advance_width = advance_width,
.left_side_bearing = left_side_bearing,
.advance_width = static_cast<u16>(long_hor_metrics[m_number_of_h_metrics - 1].advance_width),
.left_side_bearing = static_cast<i16>(left_side_bearings[glyph_id - m_number_of_h_metrics]),
};
}

6
Userland/Libraries/LibGfx/Font/OpenType/Tables.h
View file

@ -177,9 +177,9 @@ public:
GlyphHorizontalMetrics get_glyph_horizontal_metrics(u32 glyph_id) const;
private:
enum class Sizes {
LongHorMetric = 4,
LeftSideBearing = 2
struct LongHorMetric {
BigEndian<u16> advance_width;
BigEndian<i16> lsb;
};
Hmtx(ReadonlyBytes slice, u32 num_glyphs, u32 number_of_h_metrics)