javascript – D3.js在svg中间粘贴父对象

我修改了Collapsible Force Layout http://mbostock.github.io/d3/talk/20111116/force-collapsible.html示例：

……现在看起来像这样

所有圆圈现在都可以拖动.我想在svg的中间贴中间圆圈(蓝色圆圈).可能吗？谢谢.

<script>

    var width = 960,
        height = 600,
        root;

    var force = d3.layout.force()
        .linkDistance(175)
        .charge(-200)
        .gravity(0)
        .size([width, height])
        .on("tick", tick);

    var svg = d3.select("body").append("svg")
        .attr("width", width)
        .attr("height", height);

    var link = svg.selectAll(".link"),
        node = svg.selectAll(".node");

    d3.json("graph.json", function(error, json) {
      root = json;
      update();
    });

    function update() {
      var nodes = flatten(root),
          links = d3.layout.tree().links(nodes);

      // Restart the force layout.
      force
          .nodes(nodes)
          .links(links)
          .start();

      // Update links.
      link = link.data(links, function(d) { return d.target.id; });

      link.exit().remove();

      link.enter().insert("line", ".node")
          .attr("class", "link");

      // Update nodes.
      node = node.data(nodes, function(d) { return d.id; });

      node.exit().remove();

      var nodeEnter = node.enter().append("g")
          .attr("class", "node")
          .on("click", click)
          .call(force.drag)
          .attr("href", function(d) { return d.link; });

    nodeEnter.append("svg:a")
      .attr("xlink:href", function(d){return d.link;})
      .append("circle")
          .attr("r", function(d) { return Math.sqrt(d.size) / 10 || 4.5; });

      nodeEnter.append("text")
          .attr("dy", ".35em")
          .text(function(d) { return d.name; });

      node.select("circle")
          .style("fill", color);
    }

    function tick() {
      link.attr("x1", function(d) { return d.source.x; })
          .attr("y1", function(d) { return d.source.y; })
          .attr("x2", function(d) { return d.target.x; })
          .attr("y2", function(d) { return d.target.y; });

      node.attr("transform", function(d) { return "translate(" + d.x + "," + d.y + ")"; });
    }

    function color(d) {
      return d._children ? "#3182bd" // collapsed package
          : d.children ? "#2F9BC1" // expanded package
          : "#fd8d3c"; // leaf node
    }

    // Toggle children on click.
    function click(obj) {
      if (d3.event.defaultPrevented) return; // ignore drag
      if (d.children) {
        d._children = d.children;
        d.children = null;
      } else {
        d.children = d._children;
        d._children = null;
      }
      update();
    }

    // Returns a list of all nodes under the root.
    function flatten(root) {
      var nodes = [], i = 0;

      function recurse(node) {
        if (node.children) node.children.forEach(recurse);
        if (!node.id) node.id = ++i;
        nodes.push(node);
      }

      recurse(root);
      return nodes;
    }

    </script>

json文件：

{
     "name": "Me", "size": 200000, "link": "http://google.com",
     "children": [
      {"name": "Person 01", "size": 150000, "link": "http://google.com"},
      {"name": "Person 02", "size": 150000, "link": "http://yahoo.com"},
      {"name": "Person 03", "size": 150000, "link": "http://youtube.com"},
      {"name": "Person 04", "size": 150000, "link": "http://twitter.com"},
      {"name": "Person 05", "size": 150000, "link": "http://facebook.com"}
     ]
 }

解决方法:

您需要做的是在将其坐标设置为中心后将相关节点的固定属性设置为true(参见the documentation),

nodes.forEach(function(d) {
   if(d._children || d.children) {
     d.x = width/2, d.y = height/2;
     d.fixed = true;
   }
});

立即在更新功能的开始.

如果您还要禁用该节点的拖动,则可以执行此操作

nodeEnter.filter(function(d) {
           return d.children === undefined && d._children === undefined;
         })
         .call(force.drag);

而不是在所有节点上调用force.drag.完成示例here.

标签：javascript,svg,d3-js,force-layout
来源： https://codeday.me/bug/20190629/1324250.html