tailPath function

Path tailPath({ required TailSide side, required Size tooltipSize, required Rect hole, required Rect tooltip, double length = _kTailLength, double width = _kTailWidth, })

Triangle of the tail in tooltip-local coordinates.

tooltip — the tooltip's rect in the same (global) space as hole, to derive the hole's center in local coordinates; tooltipSize — the painter's canvas size (== the tooltip's size). The base sits on the tooltip's edge (half a pixel inside, so the opaque tooltip surface covers the seam); the apex extends length beyond it, toward the hole.

Implementation

Path tailPath({
  required TailSide side,
  required Size tooltipSize,
  required Rect hole,
  required Rect tooltip,
  double length = _kTailLength,
  double width = _kTailWidth,
}) {
  final half = width / 2;
  final path = Path();
  switch (side) {
    case TailSide.bottom:
      final cx =
          _clampCenter(hole.center.dx - tooltip.left, tooltipSize.width, half);
      path
        ..moveTo(cx - half, tooltipSize.height - 0.5)
        ..lineTo(cx + half, tooltipSize.height - 0.5)
        ..lineTo(cx, tooltipSize.height + length)
        ..close();
    case TailSide.top:
      final cx =
          _clampCenter(hole.center.dx - tooltip.left, tooltipSize.width, half);
      path
        ..moveTo(cx - half, 0.5)
        ..lineTo(cx + half, 0.5)
        ..lineTo(cx, -length)
        ..close();
    case TailSide.left:
      final cy =
          _clampCenter(hole.center.dy - tooltip.top, tooltipSize.height, half);
      path
        ..moveTo(0.5, cy - half)
        ..lineTo(0.5, cy + half)
        ..lineTo(-length, cy)
        ..close();
    case TailSide.right:
      final cy =
          _clampCenter(hole.center.dy - tooltip.top, tooltipSize.height, half);
      path
        ..moveTo(tooltipSize.width - 0.5, cy - half)
        ..lineTo(tooltipSize.width - 0.5, cy + half)
        ..lineTo(tooltipSize.width + length, cy)
        ..close();
  }
  return path;
}