drawPoint method
Implementation
@override
MarkElement<ElementStyle> drawPoint(Attributes item, CoordConv coord) {
final point = coord.convert(item.position.last);
final size = item.size ?? defaultSize;
return RectElement(
rect: Rect.fromCenter(center: point, width: size, height: size),
style: getPaintStyle(item, (item.shape as PointShape).hollow,
(item.shape as PointShape).strokeWidth, null, null),
tag: item.tag,
);
}