hitTextSelectionGlyphs function

Implementation

TextSelectionHit? hitTextSelectionGlyphs(
  Iterable<TextSelectionGlyph> glyphs,
  Mat2D transform,
  Vec2D point, {
  bool nearest = false,
}) {
  if (!point.x.isFinite || !point.y.isFinite) return null;
  final inverse = Mat2D();
  if (!Mat2D.invert(inverse, transform)) return null;
  final local = inverse.mapXY(point.x, point.y);
  if (!local.x.isFinite || !local.y.isFinite) return null;
  TextSelectionHit? result;
  for (final glyph in glyphs) {
    final rect = glyph.bounds;
    if (rect.isEmpty || glyph.count <= 0) continue;
    final x = local.x.clamp(rect.left, rect.right);
    final y = local.y.clamp(rect.top, rect.bottom);
    if (!nearest && (x != local.x || y != local.y)) continue;
    final root = transform.mapXY(x, y);
    final dx = root.x - point.x, dy = root.y - point.y;
    final distance = dx * dx + dy * dy;
    if (result == null || distance < result.distanceSquared) {
      var fraction = (x - rect.left) / rect.width;
      if (glyph.rtl) fraction = 1 - fraction;
      result = TextSelectionHit(
        glyph.start + (fraction * glyph.count).round(),
        distance,
      );
    }
  }
  return result;
}