Question

我正在尝试在默认的d3树布局上添加标记箭头。树布局工作正常。

我已经定义了这样的标记：

svg.append("svg:defs")
    .append("svg:marker")
    .attr("id", "arrow")    
    .attr("refX", 2)
    .attr("refY", 6)
    .attr("markerWidth", 13)
    .attr("markerHeight", 13)
    .attr("orient", "auto")
    .append("svg:path")
    .attr("d", "M2,2 L2,11 L10,6 L2,2");

并在树形布局中的链接上使用它，如：

.attr("marker", "url(#arrow)");

但标记箭头没有出现。我做错了什么？

var treeData = [{
  "name": "Top Level",
  "parent": "null",
  "children": [{
    "name": "Level 2: A",
    "parent": "Top Level",
    "children": [{
      "name": "Son of A",
      "parent": "Level 2: A"
    }, {
      "name": "Daughter of A",
      "parent": "Level 2: A"
    }]
  }, {
    "name": "Level 2: B",
    "parent": "Top Level"
  }]
}];


// ************** Generate the tree diagram	 *****************
var margin = {
    top: 20,
    right: 120,
    bottom: 20,
    left: 120
  },
  width = 960 - margin.right - margin.left,
  height = 500 - margin.top - margin.bottom;

var i = 0,
  duration = 750,
  root;

var tree = d3.layout.tree()
  .size([height, width]);

var diagonal = d3.svg.diagonal()
  .projection(function(d) {
    return [d.y, d.x];
  });

var svg = d3.select("body").append("svg")
  .attr("width", width + margin.right + margin.left)
  .attr("height", height + margin.top + margin.bottom)
  .append("g")
  .attr("transform", "translate(" + margin.left + "," + margin.top + ")");


svg.append("svg:defs")
  .append("svg:marker")
  .attr("id", "arrow")
  .attr("refX", 2)
  .attr("refY", 6)
  .attr("markerWidth", 13)
  .attr("markerHeight", 13)
  .attr("orient", "auto")
  .append("svg:path")
  .attr("d", "M2,2 L2,11 L10,6 L2,2");


root = treeData[0];
root.x0 = height / 2;
root.y0 = 0;

update(root);

d3.select(self.frameElement).style("height", "500px");

function update(source) {

  // Compute the new tree layout.
  var nodes = tree.nodes(root).reverse(),
    links = tree.links(nodes);

  // Normalize for fixed-depth.
  nodes.forEach(function(d) {
    d.y = d.depth * 180;
  });

  // Update the nodes…
  var node = svg.selectAll("g.node")
    .data(nodes, function(d) {
      return d.id || (d.id = ++i);
    });

  // Enter any new nodes at the parent's previous position.
  var nodeEnter = node.enter().append("g")
    .attr("class", "node")
    .attr("transform", function(d) {
      return "translate(" + source.y0 + "," + source.x0 + ")";
    })
    .on("click", click);

  nodeEnter.append("circle")
    .attr("r", 1e-6)
    .style("fill", function(d) {
      return d._children ? "lightsteelblue" : "#fff";
    });

  nodeEnter.append("text")
    .attr("x", function(d) {
      return d.children || d._children ? -13 : 13;
    })
    .attr("dy", ".35em")
    .attr("text-anchor", function(d) {
      return d.children || d._children ? "end" : "start";
    })
    .text(function(d) {
      return d.name;
    })
    .style("fill-opacity", 1e-6);

  // Transition nodes to their new position.
  var nodeUpdate = node.transition()
    .duration(duration)
    .attr("transform", function(d) {
      return "translate(" + d.y + "," + d.x + ")";
    });

  nodeUpdate.select("circle")
    .attr("r", 10)
    .style("fill", function(d) {
      return d._children ? "lightsteelblue" : "#fff";
    });

  nodeUpdate.select("text")
    .style("fill-opacity", 1);

  // Transition exiting nodes to the parent's new position.
  var nodeExit = node.exit().transition()
    .duration(duration)
    .attr("transform", function(d) {
      return "translate(" + source.y + "," + source.x + ")";
    })
    .remove();

  nodeExit.select("circle")
    .attr("r", 1e-6);

  nodeExit.select("text")
    .style("fill-opacity", 1e-6);

  // Update the links…
  var link = svg.selectAll("path.link")
    .data(links, function(d) {
      return d.target.id;
    });

  // Enter any new links at the parent's previous position.
  link.enter().insert("path", "g")
    .attr("class", "link")
    .attr("d", function(d) {
      var o = {
        x: source.x0,
        y: source.y0
      };
      return diagonal({
        source: o,
        target: o
      });
    })
    .attr("marker-mid", "url(#arrow)");;

  // Transition links to their new position.
  link.transition()
    .duration(duration)
    .attr("d", diagonal);

  // Transition exiting nodes to the parent's new position.
  link.exit().transition()
    .duration(duration)
    .attr("d", function(d) {
      var o = {
        x: source.x,
        y: source.y
      };
      return diagonal({
        source: o,
        target: o
      });
    })
    .remove();

  // Stash the old positions for transition.
  nodes.forEach(function(d) {
    d.x0 = d.x;
    d.y0 = d.y;
  });
}

// Toggle children on click.
function click(d) {
  if (d.children) {
    d._children = d.children;
    d.children = null;
  } else {
    d.children = d._children;
    d._children = null;
  }
  update(d);
}

.node {
  cursor: pointer;
}
.node circle {
  fill: #fff;
  stroke: steelblue;
  stroke-width: 3px;
}
.node text {
  font: 12px sans-serif;
}
.link {
  fill: none;
  stroke: #ccc;
  stroke-width: 2px;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>

Answer 1

中间标记不会出现，因为它们附加到只有起点和终点的路径，没有中间顶点。

marker-mid定义箭头或多边形标记，该箭头或多边形标记应在给定元素或基本形状的第一个和最后一个顶点以外的每个顶点处绘制。

reference

您可以做的是：

不显示标记（推荐，它会使视觉混乱而不会增加太多价值）
使用结束标记而不是中间标记（并调整最后一个顶点的位置，使其保持在圆圈的左侧，而不是其中心）
或乱码代码生成链接路径，以便在路径中间添加一个点。

另请阅读related question。

在d3树布局链接上添加标记

1 个答案: