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LibGfx: Use binary search in glyph_id_for_code_point_table_4

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No behavior change for valid ttf files (which have a trailing
0xffff endCodes entry, and a sorted endCodes array).
This commit is contained in:
Nico Weber 2022-04-03 12:29:47 -04:00 • committed by Linus Groh
parent 33d19a562f
commit 10b2b71a2c
1 changed files with 24 additions and 20 deletions
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44
Userland/Libraries/LibGfx/TrueTypeFont/Cmap.cpp
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@ -91,28 +91,32 @@ u32 Cmap::Subtable::glyph_id_for_code_point(u32 code_point) const
u32 Cmap::Subtable::glyph_id_for_code_point_table_4(u32 code_point) const
{
u32 segcount_x2 = be_u16(m_slice.offset_pointer((u32)Table4Offsets::SegCountX2));
if (m_slice.size() < segcount_x2 * (u32)Table4Sizes::NonConstMultiplier + (u32)Table4Sizes::Constant) {
if (m_slice.size() < segcount_x2 * (u32)Table4Sizes::NonConstMultiplier + (u32)Table4Sizes::Constant)
return 0;
u32 segcount = segcount_x2 / 2;
u32 l = 0, r = segcount - 1;
while (l < r) {
u32 mid = l + (r - l) / 2;
u32 end_code_point_at_mid = be_u16(m_slice.offset_pointer((u32)Table4Offsets::EndConstBase + (mid * 2)));
if (code_point <= end_code_point_at_mid)
r = mid;
else
l = mid + 1;
}
for (u32 offset = 0; offset < segcount_x2; offset += 2) {
u32 end_code_point = be_u16(m_slice.offset_pointer((u32)Table4Offsets::EndConstBase + offset));
if (code_point > end_code_point) {
continue;
}
u32 start_code_point = be_u16(m_slice.offset_pointer((u32)Table4Offsets::StartConstBase + segcount_x2 + offset));
if (code_point < start_code_point) {
break;
}
u32 delta = be_u16(m_slice.offset_pointer((u32)Table4Offsets::DeltaConstBase + segcount_x2 * 2 + offset));
u32 range = be_u16(m_slice.offset_pointer((u32)Table4Offsets::RangeConstBase + segcount_x2 * 3 + offset));
if (range == 0) {
return (code_point + delta) & 0xffff;
}
u32 glyph_offset = (u32)Table4Offsets::GlyphOffsetConstBase + segcount_x2 * 3 + offset + range + (code_point - start_code_point) * 2;
VERIFY(glyph_offset + 2 <= m_slice.size());
return (be_u16(m_slice.offset_pointer(glyph_offset)) + delta) & 0xffff;
}
return 0;
u32 offset = l * 2;
u32 start_code_point = be_u16(m_slice.offset_pointer((u32)Table4Offsets::StartConstBase + segcount_x2 + offset));
if (start_code_point > code_point)
return 0;
u32 delta = be_u16(m_slice.offset_pointer((u32)Table4Offsets::DeltaConstBase + segcount_x2 * 2 + offset));
u32 range = be_u16(m_slice.offset_pointer((u32)Table4Offsets::RangeConstBase + segcount_x2 * 3 + offset));
if (range == 0)
return (code_point + delta) & 0xffff;
u32 glyph_offset = (u32)Table4Offsets::GlyphOffsetConstBase + segcount_x2 * 3 + offset + range + (code_point - start_code_point) * 2;
VERIFY(glyph_offset + 2 <= m_slice.size());
return (be_u16(m_slice.offset_pointer(glyph_offset)) + delta) & 0xffff;
}
u32 Cmap::Subtable::glyph_id_for_code_point_table_12(u32 code_point) const