paintBoxGlyph function

bool paintBoxGlyph(Canvas canvas, Rect cell, int cp, Color fg, double lineWidth,)

Renders cp's ops into cell with fg. No-op (returns false) if cp has no programmatic ops, so the caller can fall back to the font glyph.

Implementation

bool paintBoxGlyph(Canvas canvas, Rect cell, int cp, Color fg, double lineWidth) {
  final ops = boxOps(cp, cell, lineWidth);
  if (ops.isEmpty) return false;
  final stroke = Paint()
    ..color = fg
    ..style = PaintingStyle.stroke
    ..strokeCap = StrokeCap.butt;
  // Block-element fills (RectOp) must not be anti-aliased: cell metrics are
  // sub-pixel, so AA'd edges on adjacent block cells leave half-covered seams —
  // a faint grid between cells (worst on fractional DPR / widget offset). Solid
  // pixel-aligned fills tile exactly, matching alacritty's integer-pixel
  // `draw_rect` (builtin_font.rs). Strokes/arcs keep AA for smooth diagonals
  // (alacritty likewise only anti-aliases its Xiaolin-Wu line drawing).
  final fill = Paint()
    ..style = PaintingStyle.fill
    ..isAntiAlias = false;
  for (final op in ops) {
    switch (op) {
      case LineOp(:final a, :final b, :final width):
        stroke.strokeWidth = width;
        canvas.drawLine(a, b, stroke);
      case RectOp(:final rect, :final alpha):
        fill.color = fg.withValues(alpha: fg.a * alpha);
        canvas.drawRect(rect, fill);
      case ArcOp(:final bounds, :final startAngle, :final sweepAngle, :final width):
        stroke.strokeWidth = width;
        canvas.drawArc(bounds, startAngle, sweepAngle, false, stroke);
      case DashOp(:final a, :final b, :final width, :final segments):
        stroke.strokeWidth = width;
        // Each segment occupies 2/3 of its slot, leaving a 1/3 gap.
        final dx = (b.dx - a.dx) / segments;
        final dy = (b.dy - a.dy) / segments;
        for (var i = 0; i < segments; i++) {
          final s = Offset(a.dx + dx * i, a.dy + dy * i);
          final e = Offset(a.dx + dx * (i + 0.66), a.dy + dy * (i + 0.66));
          canvas.drawLine(s, e, stroke);
        }
    }
  }
  return true;
}