Martín Lucas Golini 340d879677 Fix shaped text vertex colors, glyph blur and RTL caret mapping ...

Text sized its per-vertex color array with getTotalVertices(), which
assumed one quad per non-space character. Shaped text does not follow
that rule (clusters, ligatures, marks, zero-sized glyphs and fallback
fonts change the glyph count), so the color array could be shorter than
the geometry. The draw then read past the end of the array for the last,
visually rightmost glyphs: they disappeared or showed up as stray glyphs
in mixed Latin/Hebrew/Arabic strings.

- Size fill and outline colors from the generated geometry and rebuild
  them whenever the vertex counts change. Remove getTotalVertices().
- Never read past the color array in draw(), and draw the outline pass
  with its own vertex count instead of the fill count.
- Share one shaped glyph walker (forEachShapedGlyphQuad) between both
  setFillColor() overloads and keep it in sync with
  ensureGeometryUpdate(): same layout parameters and the same fill
  visibility test. The per-character overload advanced its vertex index
  only when a color was present, which misaligned the remaining colors.

TextLayout snapped complex-script glyph positions to whole pixels, but
simple-script glyphs used the pen position as-is. After a Hebrew or
Arabic run the pen is fractional (HarfBuzz 26.6 advances), so the Latin
glyphs that followed were drawn at sub-pixel positions and blurred. Round
simple-script positions as well. Pure Latin text is unchanged.

Caret mapping:
- Text::findCharacterPos() and findCharacterFromPos() now use the text's
  own base direction instead of TextDirection::Unspecified, so caret
  positions and hit testing agree with rendering.
- In a right-to-left paragraph, place the end-of-text caret at the left
  end of the last line instead of after the rightmost glyph.

Add TextLayout::getFirstStrongDirection(), which returns the direction of
the first strong bidi character (UAX #9 P2/P3), for upcoming
right-to-left layout support.

Update the textedit Arabic and Hebrew reference images: only punctuation
that follows RTL runs moves, now aligned to whole pixels.

2026-10-10 22:03:24 -03:00

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Fix shaped text vertex colors, glyph blur and RTL caret mapping

2026-10-10 22:03:24 -03:00