doLayout method

Implementation

@override
void doLayout(Context context, Graph graph, num width, num height) {
  var nodes = graph.nodes;
  int nodeCount = nodes.length;
  if (nodeCount == 0) {
    onLayoutEnd();
    return;
  }
  Offset center = Offset(this.center[0].convert(width), this.center[1].convert(height));
  if (nodeCount == 1) {
    nodes[0].x = center.dx;
    nodes[0].y = center.dy;
    onLayoutEnd();
    return;
  }
  List<num> radiusList = computeRadius(graph, width, height);

  ///计算角度的递增量
  var angleStep = (endAngle - startAngle) / (nodeCount - 1);

  ///节点排序
  List<GraphNode> layoutNodes = nodes;
  sortNode(graph, layoutNodes);

  for (int i = 0; i < nodeCount; ++i) {
    num r = radiusList[0] + radiusList[2] * i;
    num tmp = angleStep * i;
    num angle = clockwise ? startAngle + tmp : endAngle - tmp;
    Offset off = circlePoint(r, angle, center);
    layoutNodes[i].x = off.dx;
    layoutNodes[i].y = off.dy;
  }

  onLayoutEnd();
}