Question

我修改了Bostock's force direct graph example以通过添加标签和更改一些forceSimulation参数来生成我想要的布局：

<!DOCTYPE html>
<meta http-equiv="content-type" content="text/html; charset=UTF8">
<style>

.links line {
  stroke: #999;
  stroke-opacity: 0.6;
}

.nodes circle {
  stroke: #fff;
  stroke-width: 1.5px;
}

</style>
<svg width="960" height="600"></svg>
<script src="https://d3js.org/d3.v4.min.js" charset="urf-8"></script>
<script>

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

var color = d3.scaleOrdinal(d3.schemeCategory20);

var simulation = d3.forceSimulation()
    .force("link", d3.forceLink().id(function(d) { return d.id; }))
    .force("charge", d3.forceManyBody())
    .force("center", d3.forceCenter(width / 2, height / 2));

  d3.json("http://localhost/mail/bostock/getneighborhood.php?contact=5244", function(error, graph) {
    if (error) throw error;

  var link = svg.append("g")
      .attr("class", "links")
    .selectAll("line")
    .data(graph.links)
    .enter().append("line")
      .attr("stroke-width", function(d) { return Math.sqrt(d.value); });

  var node = svg.append("g")
  .attr("class", "nodes")
  .selectAll(".node")
  .data(graph.nodes)
  .enter().append("g")
  .attr("class", "node")
  .call(d3.drag()
    .on("start", dragstarted)
    .on("drag", dragged)
    .on("end", dragended));

  node.append("circle")
    .attr("r", 5)
    .attr("fill", function(d) { return color(d.group); });


  node.append("text")
      .attr("dx", 12)
      .attr("dy", ".32em")
      .attr("font-family", "sans-serif")
      .attr("font-size", "8px")
      .text(function(d) { return d.id; });

  var simulation = d3.forceSimulation()
    .force("link", d3.forceLink().id(function(d) { return d.id; }).distance(150).strength(1))
    .force("collide",d3.forceCollide( function(d){return d.r + 8 }).iterations(16) )
    .force("charge", d3.forceManyBody().strength(-200))
    .force("center", d3.forceCenter(width / 2, height / 2));

  simulation
      .nodes(graph.nodes)
      .on("tick", ticked);

  simulation.force("link")
      .links(graph.links);

  function ticked() {
    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 dragstarted(d) {
  if (!d3.event.active) simulation.alphaTarget(0.3).restart();
  d.fx = d.x;
  d.fy = d.y;
}

function dragged(d) {
  d.fx = d3.event.x;
  d.fy = d3.event.y;
}

function dragended(d) {
  if (!d3.event.active) simulation.alphaTarget(0);
  d.fx = null;
  d.fy = null;
}

</script>

唯一的问题是拖动功能不再起作用。谁能建议如何解决？

Answer 1

如果您查看代码，就会发现您有两个变量名为simulation。其中一个在d3.json之外...

var simulation = d3.forceSimulation()
    .force("link", d3.forceLink().id(function(d) {
        return d.id;
    }))
    .force("charge", d3.forceManyBody())
    .force("center", d3.forceCenter(width / 2, height / 2));

...和d3.json内的另一个：

var simulation = d3.forceSimulation()
    .force("link", d3.forceLink().id(function(d) {
        return d.id;
    }).distance(150).strength(1))
    .force("collide", d3.forceCollide(function(d) {
        return d.r + 8
    }).iterations(16))
    .force("charge", d3.forceManyBody().strength(-200))
    .force("center", d3.forceCenter(width / 2, height / 2));

移动节点的模拟是内部模拟。但是，由于函数范围，拖动函数指的是外部变量。

解决方案：只保留一个模拟，在 d3.json之外。

对forceSimulation的更改禁用拖动

1 个答案: