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LibGfx: Decouple glyph positions calculation from draw_text_run()

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This change separates a part of the `draw_text_run()` function, which
is responsible for calculating the positions for glyphs that need to be
painted, into a separate function called `get_glyph_run()`.

It is a part of the preparation for text run painting using OpenGL,
where we can't immediately blit glyph bitmaps but instead need to
prepare a sequence of quads for them in advance.
This commit is contained in:
Aliaksandr Kalenik 2023-11-05 00:17:04 +01:00 • committed by Andreas Kling
parent 3ac77dac99
commit efdbd8238e
4 changed files with 121 additions and 61 deletions
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58
Userland/Libraries/LibGfx/Painter.cpp
View file

@ -1416,48 +1416,14 @@ void Painter::draw_glyph_or_emoji(FloatPoint point, u32 code_point, Font const&
void Painter::draw_glyph_or_emoji(FloatPoint point, Utf8CodePointIterator& it, Font const& font, Color color)
{
u32 code_point = *it;
auto next_code_point = it.peek(1);
ScopeGuard consume_variation_selector = [&, initial_it = it] {
static auto const variation_selector = Unicode::property_from_string("Variation_Selector"sv);
if (!variation_selector.has_value())
return;
// 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.
if (next_code_point.has_value() && Unicode::code_point_has_property(*next_code_point, *variation_selector))
++it;
};
// NOTE: We don't check for emoji
auto font_contains_glyph = font.contains_glyph(code_point);
auto check_for_emoji = !font.has_color_bitmaps() && Unicode::could_be_start_of_emoji_sequence(it, font_contains_glyph ? Unicode::SequenceType::EmojiPresentation : Unicode::SequenceType::Any);
// 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;
auto draw_glyph_or_emoji = prepare_draw_glyph_or_emoji(point, it, font);
if (draw_glyph_or_emoji.has<DrawGlyph>()) {
auto& glyph = draw_glyph_or_emoji.get<DrawGlyph>();
draw_glyph(glyph.position, glyph.code_point, *glyph.font, color);
} else {
auto& emoji = draw_glyph_or_emoji.get<DrawEmoji>();
draw_emoji(emoji.position, *emoji.emoji, *emoji.font);
}
// 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.to_type<int>(), *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);
}
void Painter::draw_glyph(IntPoint point, u32 code_point, Color color)
@ -2473,8 +2439,14 @@ void Painter::draw_text_run(IntPoint baseline_start, Utf8View const& string, Fon
void Painter::draw_text_run(FloatPoint baseline_start, Utf8View const& string, Font const& font, Color color)
{
for_each_glyph_position(baseline_start, string, font, [&](GlyphPosition glyph_position) {
draw_glyph_or_emoji(glyph_position.position, glyph_position.it, font, color);
for_each_glyph_position(baseline_start, string, font, [&](DrawGlyphOrEmoji glyph_or_emoji) {
if (glyph_or_emoji.has<DrawGlyph>()) {
auto& glyph = glyph_or_emoji.get<DrawGlyph>();
draw_glyph(glyph.position, glyph.code_point, *glyph.font, color);
} else {
auto& emoji = glyph_or_emoji.get<DrawEmoji>();
draw_emoji(emoji.position, *emoji.emoji, *emoji.font);
}
});
}