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LibGfx: Make OpenType versioned tables more consistent

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Maxp had the shared fields duplicated, and OS2 embedded each version's
struct in the next. Instead, let's use inheritance to avoid duplicating
shared fields while still allowing them to be directly accessed.

While I'm at it, rename the Maxp and GPOS table structs to just be
VersionX_Y, because they're not ambiguous with anything else.

LibGfx: Rename GPOSHeader to HeaderVersion1_0

Because there's a version 1.1 as well, which we'll eventually want to
support.
This commit is contained in:
Sam Atkins 2023-10-26 16:48:52 +01:00 • committed by Andreas Kling
parent 75376d6834
commit d4e1305413
Notes: sideshowbarker 2024-07-17 02:23:25 +09:00
2 changed files with 15 additions and 19 deletions
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8
Userland/Libraries/LibGfx/Font/OpenType/Tables.cpp
View file

@ -124,15 +124,15 @@ ErrorOr<Maxp> Maxp::from_slice(ReadonlyBytes slice)
Version16Dot16 const& version = *bit_cast<Version16Dot16 const*>(slice.data());
if (version.major == 0 && version.minor == 5) {
if (slice.size() < sizeof(MaximumProfileVersion0_5))
if (slice.size() < sizeof(Version0_5))
return Error::from_string_literal("Could not load Maxp: Not enough data");
return Maxp(bit_cast<MaximumProfileVersion0_5 const*>(slice.data()));
return Maxp(bit_cast<Version0_5 const*>(slice.data()));
}
if (version.major == 1 && version.minor == 0) {
if (slice.size() < sizeof(MaximumProfileVersion1_0))
if (slice.size() < sizeof(Version1_0))
return Error::from_string_literal("Could not load Maxp: Not enough data");
return Maxp(bit_cast<MaximumProfileVersion1_0 const*>(slice.data()));
return Maxp(bit_cast<Version1_0 const*>(slice.data()));
}
return Error::from_string_literal("Could not load Maxp: Unrecognized version");

26
Userland/Libraries/LibGfx/Font/OpenType/Tables.h
View file

@ -176,15 +176,13 @@ public:
u16 num_glyphs() const;
private:
struct [[gnu::packed]] MaximumProfileVersion0_5 {
struct [[gnu::packed]] Version0_5 {
Version16Dot16 version;
BigEndian<u16> num_glyphs;
};
static_assert(AssertSize<MaximumProfileVersion0_5, 6>());
static_assert(AssertSize<Version0_5, 6>());
struct [[gnu::packed]] MaximumProfileVersion1_0 {
Version16Dot16 version;
BigEndian<u16> num_glyphs;
struct [[gnu::packed]] Version1_0 : Version0_5 {
BigEndian<u16> max_points;
BigEndian<u16> max_contours;
BigEndian<u16> max_composite_points;
@ -199,16 +197,16 @@ private:
BigEndian<u16> max_component_elements;
BigEndian<u16> max_component_depths;
};
static_assert(AssertSize<MaximumProfileVersion1_0, 32>());
static_assert(AssertSize<Version1_0, 32>());
Maxp(Variant<MaximumProfileVersion0_5 const*, MaximumProfileVersion1_0 const*> data)
Maxp(Variant<Version0_5 const*, Version1_0 const*> data)
: m_data(move(data))
{
VERIFY(m_data.visit([](auto const* any) { return any != nullptr; }));
}
// NOTE: Whichever pointer is present is non-null, but Variant can't contain references.
Variant<MaximumProfileVersion0_5 const*, MaximumProfileVersion1_0 const*> m_data;
Variant<Version0_5 const*, Version1_0 const*> m_data;
};
struct GlyphHorizontalMetrics {
@ -325,15 +323,13 @@ private:
};
static_assert(AssertSize<Version0, 78>());
struct [[gnu::packed]] Version1 {
Version0 version0;
struct [[gnu::packed]] Version1 : Version0 {
BigEndian<u32> ul_code_page_range1;
BigEndian<u32> ul_code_page_range2;
};
static_assert(AssertSize<Version1, 86>());
struct [[gnu::packed]] Version2 {
Version1 version1;
struct [[gnu::packed]] Version2 : Version1 {
BigEndian<i16> sx_height;
BigEndian<i16> s_cap_height;
BigEndian<u16> us_default_char;
@ -698,14 +694,14 @@ static_assert(AssertSize<ClassDefFormat2, 4>());
class GPOS {
public:
// https://learn.microsoft.com/en-us/typography/opentype/spec/gpos#gpos-header
struct [[gnu::packed]] GPOSHeader {
struct [[gnu::packed]] Version1_0 {
BigEndian<u16> major_version;
BigEndian<u16> minor_version;
Offset16 script_list_offset;
Offset16 feature_list_offset;
Offset16 lookup_list_offset;
};
static_assert(AssertSize<GPOSHeader, 10>());
static_assert(AssertSize<Version1_0, 10>());
// https://learn.microsoft.com/en-us/typography/opentype/spec/gpos#pair-adjustment-positioning-format-1-adjustments-for-glyph-pairs
struct [[gnu::packed]] PairPosFormat1 {
@ -755,7 +751,7 @@ public:
Y_ADVANCE_DEVICE = 0x0080,
};
GPOSHeader const& header() const { return *bit_cast<GPOSHeader const*>(m_slice.data()); }
Version1_0 const& header() const { return *bit_cast<Version1_0 const*>(m_slice.data()); }
Optional<i16> glyph_kerning(u16 left_glyph_id, u16 right_glyph_id) const;