paint method
Implementation
@override
void paint(PaintingContext context, Size viewport, {Offset? origin}) {
Canvas canvas = context.canvas;
if (origin != null) {
canvas.save();
canvas.translate(origin.dx, origin.dy);
}
verticalScrollbar.paint(canvas, viewport);
horizontalScrollbar.paint(canvas, viewport);
if (origin != null) {
canvas.restore();
}
}