layout method
给定一个区域范围和节点,对该节点的Children进行布局(不包含孩子的孩子)
Implementation
@override
void layout(TreeMapNode root, Rect area) {
BinaryNode binaryNode = _convertToBinaryNode(null, root, false);
binaryNode.position = area;
_layoutChildren(area, binaryNode);
for (BinaryNode element in binaryNode.children) {
element.layoutNode.cur.position = element.position;
}
}