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LibGfx: Cache family, width, weight, and slope for OpenType fonts

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These properties could be cached in the font object once they are
decoded from the table for the first time to make subsequent access
faster.

This change makes `Node::scaled_font()` in LibWeb go down from 6% to
1.5% in my profiles because building a font cache key is now a lot
cheaper.
This commit is contained in:
Aliaksandr Kalenik 2023-12-09 09:03:36 +01:00 • committed by Andreas Kling
parent af13bd8af0
commit 7ae229ead7
2 changed files with 49 additions and 28 deletions
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72
Userland/Libraries/LibGfx/Font/OpenType/Font.cpp
View file

@ -495,10 +495,15 @@ u16 Font::units_per_em() const
String Font::family() const
{
auto string = m_name.typographic_family_name();
if (!string.is_empty())
return string;
return m_name.family_name();
if (!m_family.has_value()) {
m_family = [&] {
auto string = m_name.typographic_family_name();
if (!string.is_empty())
return string;
return m_name.family_name();
}();
}
return *m_family;
}
String Font::variant() const
@ -511,40 +516,51 @@ String Font::variant() const
u16 Font::weight() const
{
constexpr u16 bold_bit { 1 };
if (m_os2.has_value() && m_os2->weight_class())
return m_os2->weight_class();
if (m_head.style() & bold_bit)
return 700;
return 400;
if (!m_weight.has_value()) {
m_weight = [&]() -> u16 {
constexpr u16 bold_bit { 1 };
if (m_os2.has_value() && m_os2->weight_class())
return m_os2->weight_class();
if (m_head.style() & bold_bit)
return 700;
return 400;
}();
}
return *m_weight;
}
u16 Font::width() const
{
if (m_os2.has_value()) {
return m_os2->width_class();
if (!m_width.has_value()) {
m_width = [&]() -> u16 {
if (m_os2.has_value())
return m_os2->width_class();
return Gfx::FontWidth::Normal;
}();
}
return Gfx::FontWidth::Normal;
return *m_width;
}
u8 Font::slope() const
{
// https://docs.microsoft.com/en-us/typography/opentype/spec/os2
constexpr u16 italic_selection_bit { 1 };
constexpr u16 oblique_selection_bit { 512 };
// https://docs.microsoft.com/en-us/typography/opentype/spec/head
constexpr u16 italic_style_bit { 2 };
if (!m_slope.has_value()) {
m_slope = [&]() -> u8 {
// https://docs.microsoft.com/en-us/typography/opentype/spec/os2
constexpr u16 italic_selection_bit { 1 };
constexpr u16 oblique_selection_bit { 512 };
// https://docs.microsoft.com/en-us/typography/opentype/spec/head
constexpr u16 italic_style_bit { 2 };
if (m_os2.has_value() && m_os2->selection() & oblique_selection_bit)
return 2;
if (m_os2.has_value() && m_os2->selection() & italic_selection_bit)
return 1;
if (m_head.style() & italic_style_bit)
return 1;
return 0;
if (m_os2.has_value() && m_os2->selection() & oblique_selection_bit)
return 2;
if (m_os2.has_value() && m_os2->selection() & italic_selection_bit)
return 1;
if (m_head.style() & italic_style_bit)
return 1;
return 0;
}();
}
return *m_slope;
}
bool Font::is_fixed_width() const

5
Userland/Libraries/LibGfx/Font/OpenType/Font.h
View file

@ -138,6 +138,11 @@ private:
mutable HashMap<u32, i16> m_kerning_cache;
Optional<String> mutable m_family;
Optional<u16> mutable m_width;
Optional<u16> mutable m_weight;
Optional<u8> mutable m_slope;
GlyphPage const& glyph_page(size_t page_index) const;
void populate_glyph_page(GlyphPage&, size_t page_index) const;
};