drawXAxis method
designs the x axis canvas: is the object we are going to draw size: is the size of the area where we are going to draw returns an array containing: firs two are coordinates where we'll start building the markers of this axis and the last one are real points in the x axis
Implementation
List<int> drawXAxis(Canvas canvas, Size size) {
//par de valores para x e y
const double x1 = 10;
double x2 = size.width - 10;
double y1 = size.height - 30;
double y2 = size.height - 30;
final p1 = Offset(x1, y1);
final p2 = Offset(x2, y2);
final paint = Paint()
..color = Colors.black
..style = PaintingStyle.stroke
..strokeWidth = 1;
canvas.drawLine(p1, p2, paint);
return [x1.toInt() + 10, y1.toInt(), x1.toInt()];
}