paintSurface method
Implementation
void paintSurface(Canvas canvas) {
//canvas.drawPath(outerPath, gridPaint);
for (int i = 1; i < columns; i++) {
var start = Offset(i * (outerRect.width / columns), outerRect.top);
var end = Offset(i * outerRect.width / columns, outerRect.height);
canvas.drawLine(start, end, gridPaint);
}
}