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LibGfx: Use LibUnicode to filter code points that cannot start an emoji

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Timothy Flynn 2023-02-23 08:53:35 -05:00 • committed by Linus Groh
parent 392c8c99aa
commit 8be43cd3bf
2 changed files with 7 additions and 37 deletions
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27
Userland/Libraries/LibGfx/Font/Emoji.cpp
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@ -51,35 +51,10 @@ Bitmap const* Emoji::emoji_for_code_points(ReadonlySpan<u32> const& code_points)
return bitmap.ptr();
}
template<typename CodePointIterator>
static bool could_be_emoji(CodePointIterator const& it)
{
if (it.done())
return false;
static constexpr u32 supplementary_private_use_area_b_first_code_point = 0x100000;
if (*it >= supplementary_private_use_area_b_first_code_point) {
// We use Supplementary Private Use Area-B for custom Serenity emoji.
return true;
}
static auto const emoji_property = Unicode::property_from_string("Emoji"sv);
if (!emoji_property.has_value()) {
// This means Unicode data generation is disabled. Always check the disk in that case.
return true;
}
return Unicode::code_point_has_property(*it, *emoji_property);
}
template<typename CodePointIterator>
static Bitmap const* emoji_for_code_point_iterator_impl(CodePointIterator& it)
{
// NOTE: I'm sure this could be more efficient, e.g. by checking if each code point falls
// into a certain range in the loop below (emojis, modifiers, variation selectors, ZWJ),
// and bailing out early if not. Current worst case is 10 file lookups for any sequence of
// code points (if the first glyph isn't part of the font in regular text rendering).
if (!could_be_emoji(it))
if (!Unicode::could_be_start_of_emoji_sequence(it))
return nullptr;
constexpr size_t max_emoji_code_point_sequence_length = 10;