drawLine function
Implementation
void drawLine(Canvas canvas, Offset start, Offset end, Paint painter) {
Paint _painter = painter
..color = Colors.indigoAccent
..style = PaintingStyle.stroke
..strokeWidth = 5;
Path _path = Path();
_path.moveTo(start.dx, start.dy);
_path.lineTo(end.dx, end.dy);
canvas.drawPath(_path, _painter);
}