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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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@ -75,23 +75,33 @@ enum class IncludeLeftBearing {
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No
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};
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struct GlyphPosition {
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struct DrawGlyph {
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FloatPoint position;
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float glyph_width;
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AK::Utf8CodePointIterator& it;
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u32 code_point;
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Font const* font;
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};
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struct DrawEmoji {
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IntPoint position;
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Gfx::Bitmap const* emoji;
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Font const* font;
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};
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using DrawGlyphOrEmoji = Variant<DrawGlyph, DrawEmoji>;
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Variant<DrawGlyph, DrawEmoji> prepare_draw_glyph_or_emoji(FloatPoint point, Utf8CodePointIterator& it, Font const& font);
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template<typename Callback>
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void for_each_glyph_position(FloatPoint start, Utf8View text, Font const& font, Callback callback, IncludeLeftBearing include_left_bearing = IncludeLeftBearing::No)
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void for_each_glyph_position(FloatPoint baseline_start, Utf8View string, Font const& font, Callback callback, IncludeLeftBearing include_left_bearing = IncludeLeftBearing::No)
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{
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float space_width = font.glyph_width(' ') + font.glyph_spacing();
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u32 last_code_point = 0;
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auto point = start;
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auto point = baseline_start;
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point.translate_by(0, -font.pixel_metrics().ascent);
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for (auto code_point_iterator = text.begin(); code_point_iterator != text.end(); ++code_point_iterator) {
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for (auto code_point_iterator = string.begin(); code_point_iterator != string.end(); ++code_point_iterator) {
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auto code_point = *code_point_iterator;
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if (should_paint_as_space(code_point)) {
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point.translate_by(space_width, 0);
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@ -106,18 +116,19 @@ void for_each_glyph_position(FloatPoint start, Utf8View text, Font const& font,
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auto it = code_point_iterator; // The callback function will advance the iterator, so create a copy for this lookup.
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auto glyph_width = font.glyph_or_emoji_width(it) + font.glyph_spacing();
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auto glyph_point = point;
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if (include_left_bearing == IncludeLeftBearing::Yes)
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glyph_point += FloatPoint(font.glyph_left_bearing(code_point), 0);
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auto glyph_or_emoji = prepare_draw_glyph_or_emoji(point, code_point_iterator, font);
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if (include_left_bearing == IncludeLeftBearing::Yes) {
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if (glyph_or_emoji.has<DrawGlyph>())
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glyph_or_emoji.get<DrawGlyph>().position += FloatPoint(font.glyph_left_bearing(code_point), 0);
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}
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callback(GlyphPosition {
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.position = glyph_point,
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.glyph_width = glyph_width,
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.it = code_point_iterator });
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callback(glyph_or_emoji);
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point.translate_by(glyph_width, 0);
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last_code_point = code_point;
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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 = IncludeLeftBearing::No);
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}
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