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LibGfx/OpenType: Use typographic metrics when asked to by the OS/2 table

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This commit is contained in:
Andreas Kling 2023-01-04 19:27:25 +01:00
parent c3018f8beb
commit bb0c5f8ab4
2 changed files with 36 additions and 7 deletions
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41
Userland/Libraries/LibGfx/Font/OpenType/Font.cpp
View file

@ -518,14 +518,24 @@ ErrorOr<NonnullRefPtr<Font>> Font::try_load_from_offset(ReadonlyBytes buffer, u3
Gfx::ScaledFontMetrics Font::metrics([[maybe_unused]] float x_scale, float y_scale) const
{
auto ascender = m_hhea.ascender() * y_scale;
auto descender = m_hhea.descender() * y_scale;
auto line_gap = m_hhea.line_gap() * y_scale;
i16 raw_ascender;
i16 raw_descender;
i16 raw_line_gap;
if (m_os2.has_value() && m_os2->use_typographic_metrics()) {
raw_ascender = m_os2->typographic_ascender();
raw_descender = m_os2->typographic_descender();
raw_line_gap = m_os2->typographic_line_gap();
} else {
raw_ascender = m_hhea.ascender();
raw_descender = m_hhea.descender();
raw_line_gap = m_hhea.line_gap();
}
return Gfx::ScaledFontMetrics {
.ascender = ascender,
.descender = descender,
.line_gap = line_gap,
.ascender = static_cast<float>(raw_ascender) * y_scale,
.descender = static_cast<float>(raw_descender) * y_scale,
.line_gap = static_cast<float>(raw_line_gap) * y_scale,
};
}
@ -561,7 +571,19 @@ RefPtr<Gfx::Bitmap> Font::rasterize_glyph(u32 glyph_id, float x_scale, float y_s
}
auto glyph_offset = m_loca.get_glyph_offset(glyph_id);
auto glyph = m_glyf.glyph(glyph_offset);
return glyph.rasterize(m_hhea.ascender(), m_hhea.descender(), x_scale, y_scale, subpixel_offset, [&](u16 glyph_id) {
i16 ascender = 0;
i16 descender = 0;
if (m_os2.has_value() && m_os2->use_typographic_metrics()) {
ascender = m_os2->typographic_ascender();
descender = m_os2->typographic_descender();
} else {
ascender = m_hhea.ascender();
descender = m_hhea.descender();
}
return glyph.rasterize(ascender, descender, x_scale, y_scale, subpixel_offset, [&](u16 glyph_id) {
if (glyph_id >= glyph_count()) {
glyph_id = 0;
}
@ -657,4 +679,9 @@ i16 OS2::typographic_line_gap() const
return header().s_typo_line_gap;
}
bool OS2::use_typographic_metrics() const
{
return header().fs_selection & 0x80;
}
}

2
Userland/Libraries/LibGfx/Font/OpenType/Tables.h
View file

@ -206,6 +206,8 @@ public:
i16 typographic_descender() const;
i16 typographic_line_gap() const;
bool use_typographic_metrics() const;
explicit OS2(ReadonlyBytes slice)
: m_slice(slice)
{