Wrapping Text in D3

I would like to get the text to wrap on the following D3 tree so that instead of

Foo is not a long word

each line is wrapped to

Foo is
not a
long word

I have tried making the text a ‘foreignObject’ rather than a text object and the text does indeed wrap, but it doesn’t move on the tree animation and is all grouped in the upper left hand corner.

Code located at

http://jsfiddle.net/mikeyai/X43X5/1/

Javascript:

var width = 960,
    height = 500;

var tree = d3.layout.tree()
    .size([width - 20, height - 20]);

var root = {},
    nodes = tree(root);

root.parent = root;
root.px = root.x;
root.py = root.y;

var diagonal = d3.svg.diagonal();

var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height)
  .append("g")
    .attr("transform", "translate(10,10)");

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

var duration = 750,
    timer = setInterval(update, duration);

function update() {
  if (nodes.length >= 500) return clearInterval(timer);

  // Add a new node to a random parent.
  var n = {id: nodes.length},
      p = nodes[Math.random() * nodes.length | 0];
  if (p.children) p.children.push(n); else p.children = [n];
  nodes.push(n);

  // Recompute the layout and data join.
  node = node.data(tree.nodes(root), function(d) { return d.id; });
  link = link.data(tree.links(nodes), function(d) { return d.source.id + "-" + d.target.id; });

  // Add entering nodes in the parent’s old position.
  node.enter().append("text")
      .attr("class", "node")
      .attr("x", function(d) { return d.parent.px; })
      .attr("y", function(d) { return d.parent.py; })
        .text('Foo is not a long word');

  // Add entering links in the parent’s old position.
  link.enter().insert("path", ".node")
      .attr("class", "link")
      .attr("d", function(d) {
        var o = {x: d.source.px, y: d.source.py};
        return diagonal({source: o, target: o});
      });

  // Transition nodes and links to their new positions.
  var t = svg.transition()
      .duration(duration);

  t.selectAll(".link")
      .attr("d", diagonal);

  t.selectAll(".node")
      .attr("x", function(d) { return d.px = d.x; })
      .attr("y", function(d) { return d.py = d.y; });
}

Answer

You can modify Mike Bostock’s “Wrapping Long Labels” example to add <tspan> elements to your <text> nodes. There are two major changes required to add wrapped text to your nodes. I didn’t delve into having the text update its position during transitions, but it shouldn’t be too hard to add.

The first is to add a function wrap, based off of the function in the above example. wrap will take care of adding <tspan> elements to make your text fit within a certain width:

function wrap(text, width) {
    text.each(function () {
        var text = d3.select(this),
            words = text.text().split(/s+/).reverse(),
            word,
            line = [],
            lineNumber = 0,
            lineHeight = 1.1, // ems
            x = text.attr("x"),
            y = text.attr("y"),
            dy = 0, //parseFloat(text.attr("dy")),
            tspan = text.text(null)
                        .append("tspan")
                        .attr("x", x)
                        .attr("y", y)
                        .attr("dy", dy + "em");
        while (word = words.pop()) {
            line.push(word);
            tspan.text(line.join(" "));
            if (tspan.node().getComputedTextLength() > width) {
                line.pop();
                tspan.text(line.join(" "));
                line = [word];
                tspan = text.append("tspan")
                            .attr("x", x)
                            .attr("y", y)
                            .attr("dy", ++lineNumber * lineHeight + dy + "em")
                            .text(word);
            }
        }
    });
}

The second change is that instead of setting the text of each node, you need to call wrap for each node:

// Add entering nodes in the parent’s old position.
node.enter().append("text")
    .attr("class", "node")
    .attr("x", function (d) { return d.parent.px; })
    .attr("y", function (d) { return d.parent.py; })
    .text("Foo is not a long word")
    .call(wrap, 30); // wrap the text in <= 30 pixels