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LibGfx: Add basic variation selector and regional indicator support :^)

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I'm sure there's a spec for this somewhere, but this is a first working
approximation.

Closes #3315.
This commit is contained in:
Linus Groh 2022-02-22 22:22:10 +00:00
parent cab032f1ee
commit c5c026890e
1 changed files with 38 additions and 3 deletions
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41
Userland/Libraries/LibGfx/Painter.cpp
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@ -1249,21 +1249,56 @@ void Painter::draw_glyph_or_emoji(IntPoint const& point, u32 code_point, Font co
void Painter::draw_glyph_or_emoji(IntPoint const& point, Utf8CodePointIterator& it, Font const& font, Color color)
{
// FIXME: Handle variation selectors. Additionally, some emojis start with a 'regular' character,
// so the 'font contains' check isn't sufficient for all of them - we'll have to peek.
// FIXME: These should live somewhere else.
constexpr u32 text_variation_selector = 0xFE0E;
constexpr u32 emoji_variation_selector = 0xFE0F;
constexpr u32 regional_indicator_symbol_a = 0x1F1E6;
constexpr u32 regional_indicator_symbol_z = 0x1F1FF;
auto initial_it = it;
u32 code_point = *it;
auto next_code_point = it.peek(1);
if (font.contains_glyph(code_point)) {
ScopeGuard consume_variation_selector = [&] {
// If we advanced the iterator to consume an emoji sequence, don't look for another variation selector.
if (initial_it != it)
return;
// Otherwise, discard one code point if it's a variation selector.
auto next_code_point = it.peek(1);
if (next_code_point == text_variation_selector || next_code_point == emoji_variation_selector)
++it;
};
auto code_point_is_regional_indicator = code_point >= regional_indicator_symbol_a && code_point <= regional_indicator_symbol_z;
auto font_contains_glyph = font.contains_glyph(code_point);
auto check_for_emoji = false
// Flag emojis consist of two regional indicators.
|| code_point_is_regional_indicator
// U+00A9 (copyright) or U+00AE (registered) are text glyphs by default,
// keycap emojis ({#,*,0-9} U+FE0F U+20E3) start with a regular ASCII character.
// Both cases are handled by peeking for the variation selector.
|| next_code_point == emoji_variation_selector;
// If the font contains the glyph, and we know it's not the start of an emoji, draw a text glyph.
if (font_contains_glyph && !check_for_emoji) {
draw_glyph(point, code_point, font, color);
return;
}
// If we didn't find a text glyph, or have an emoji variation selector or regional indicator, try to draw an emoji glyph.
if (auto const* emoji = Emoji::emoji_for_code_point_iterator(it)) {
draw_emoji(point, *emoji, font);
return;
}
// If that failed, but we have a text glyph fallback, draw that.
if (font_contains_glyph) {
draw_glyph(point, code_point, font, color);
return;
}
// No suitable glyph found, draw a replacement character.
dbgln_if(EMOJI_DEBUG, "Failed to find a glyph or emoji for code_point {}", code_point);
draw_glyph(point, 0xFFFD, font, color);
}