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LibGfx: Decouple glyph positions calculation from draw_text_run()
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.
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4 changed files with 121 additions and 61 deletions
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@ -6,6 +6,10 @@
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*/
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#include "TextLayout.h"
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#include "Font/Emoji.h"
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#include <AK/Debug.h>
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#include <LibUnicode/CharacterTypes.h>
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#include <LibUnicode/Emoji.h>
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namespace Gfx {
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@ -192,4 +196,74 @@ DeprecatedString TextLayout::elide_text_from_right(Utf8View text) const
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return text.as_string();
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}
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DrawGlyphOrEmoji prepare_draw_glyph_or_emoji(FloatPoint point, Utf8CodePointIterator& it, Font const& font)
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{
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u32 code_point = *it;
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auto next_code_point = it.peek(1);
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ScopeGuard consume_variation_selector = [&, initial_it = it] {
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static auto const variation_selector = Unicode::property_from_string("Variation_Selector"sv);
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if (!variation_selector.has_value())
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return;
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// If we advanced the iterator to consume an emoji sequence, don't look for another variation selector.
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if (initial_it != it)
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return;
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// Otherwise, discard one code point if it's a variation selector.
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if (next_code_point.has_value() && Unicode::code_point_has_property(*next_code_point, *variation_selector))
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++it;
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};
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// NOTE: We don't check for emoji
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auto font_contains_glyph = font.contains_glyph(code_point);
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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);
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// If the font contains the glyph, and we know it's not the start of an emoji, draw a text glyph.
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if (font_contains_glyph && !check_for_emoji) {
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return DrawGlyph {
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.position = point,
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.code_point = code_point,
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.font = &font,
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};
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}
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// If we didn't find a text glyph, or have an emoji variation selector or regional indicator, try to draw an emoji glyph.
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if (auto const* emoji = Emoji::emoji_for_code_point_iterator(it)) {
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return DrawEmoji {
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.position = point.to_type<int>(),
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.emoji = emoji,
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.font = &font,
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};
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}
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// If that failed, but we have a text glyph fallback, draw that.
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if (font_contains_glyph) {
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return DrawGlyph {
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.position = point,
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.code_point = code_point,
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.font = &font,
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};
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}
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// No suitable glyph found, draw a replacement character.
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dbgln_if(EMOJI_DEBUG, "Failed to find a glyph or emoji for code_point {}", code_point);
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return DrawGlyph {
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.position = point,
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.code_point = 0xFFFD,
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.font = &font,
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};
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}
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Vector<DrawGlyphOrEmoji> get_glyph_run(FloatPoint baseline_start, Utf8View const& string, Font const& font, IncludeLeftBearing include_left_bearing)
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{
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Vector<DrawGlyphOrEmoji> glyphs_or_emojis;
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for_each_glyph_position(
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baseline_start, string, font, [&](auto glyph_or_emoji) {
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glyphs_or_emojis.append(glyph_or_emoji);
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},
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include_left_bearing);
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return glyphs_or_emojis;
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}
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}
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