javascript - 如何将标题、背景和边框作为 svg 外部图像添加到要下载的 d3js 树的克隆元素

Question

我有一个可以下载的 d3js 树，我想从外部 .svg 文件中添加标题、蔓藤花纹背景和蔓藤花纹边框，以获得更好的视觉效果。

我有 3 个外部文件：title_3.png（稍后我将使用 svg 等效文件）、background-F4EED7.svg 和 border_1.svg。我需要将标题居中到图表的中间，并允许根据生成的树的长度和深度调整标题的高度。

实现这一目标的最佳方法是什么？

var treeData = [{
  "name": "Top Level",
  "parent": "null",
  "remark": "yes",
  "children": [{
      "name": "Level 2: A",
      "parent": "Top Level",
      "remark": "yes",
      "children": [{
          "name": "Son of A",
          "parent": "Level 2: A",
          "remark": "null"
        },
        {
          "name": "Daughter of A",
          "parent": "Level 2: A",
          "remark": "null"
        }
      ]
    },
    {
      "name": "Level 2: B",
      "parent": "Top Level",
      "remark": "null"
    }
  ]
}];

//*************************************************************************************
// 1. Create the button
var button = document.createElement("button");
button.innerHTML = "download file";
//*************************************************************************************

// ************** 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,
  rectW = 100,
  rectH = 30,
  duration = 750,
  root;

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

//swap x and y for vertical
var diagonal = d3.svg.diagonal()
  .projection(function(d) {
    return [d.x + rectW / 2, d.y + rectH / 2];
  });

var gElement = document.createElementNS(d3.ns.prefix.svg, 'g');
gElement.setAttribute("id", "fg");
console.log(gElement);

var svg = d3.select("body").append("svg")
  .attr("width", width + margin.right + margin.left)
  .attr("height", height + margin.top + margin.bottom)
  .append(function() {
    return gElement;
  }) //The argument to .append() has to be a function, you can't just pass element to it.
  .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

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.
  //swap x and y for vertical
  var nodeEnter = node.enter().append("g")
    .attr("class", "node")
    .attr("transform", function(d) {
      return "translate(" + source.x0 + "," + source.y0 + ")";
    })
    .on("click", click);

  nodeEnter.append("rect")
    //nodeEnter.append("circle")
    //  .attr("r", 1e-6)
    .attr("width", rectW)
    .attr("height", rectH)
    .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);

  // Filter to put tooltip only on nodes that have information associated with it
  var nodesWithInfo = nodeEnter.filter(function(d) {
    return (d.remark != 'null')
  })
  nodesWithInfo
    .append("circle")
    .attr("export-ignore", true)
    .attr("cx", 96)
    .attr("cy", 7)
    .attr("r", 10);

  nodesWithInfo
    .append("text")
    .attr("export-ignore", true)
    .attr("id", "infoText")
    .attr("x", 96)
    .attr("y", 7)
    .attr("dy", ".30em")
    .style("font-style", "italic")
    .style("font-family", "serif")
    .style("font-weight", "bold")
    .text("i");

  // Transition nodes to their new position.
  //swap x and y for vertical layout
  var nodeUpdate = node.transition()
    .duration(duration)
    .attr("transform", function(d) {
      return "translate(" + d.x + "," + d.y + ")";
    });

  //nodeUpdate.select("circle")
  nodeUpdate.select("rect")
    .attr("width", rectW)
    .attr("height", rectH)
    .style("stroke", "black")
    //  .attr("r", 10)
    .style("fill", function(d) {
      return d._children ? "lightsteelblue" : "#fff";
    });

  nodeUpdate.select("text")
    .attr("x", rectW / 2)
    .attr("y", rectH / 2)
    .attr("dy", ".35em")
    .attr("text-anchor", "middle")
    .style("fill-opacity", 1);

  // Transition exiting nodes to the parent's new position.
  //vertical switch x and y positions
  var nodeExit = node.exit().transition()
    .duration(duration)
    .attr("transform", function(d) {
      return "translate(" + source.x + "," + source.y + ")";
    })
    .remove();

  nodeExit.select("rect")
    .attr("width", rectW)
    .attr("height", rectH)
    .style("stroke", "black");
  //  .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("stroke", "#ccc")
    .attr("fill", "none")
    .attr("stroke-width", "2px")
    .attr("d", function(d) {
      var o = {
        x: source.x0,
        y: source.y0
      };
      return diagonal({
        source: o,
        target: o
      });
    });

  // 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);
}

//*************************************************************************************
// 2. Append button somewhere
var body = document.getElementsByTagName("body")[0];
body.appendChild(button)
  .setAttribute("transform", "translate(" + 0 + "," + 0 + ")");

//*************************************************************************************

function svgDataURL(svg) {
  var svgAsXML = (new XMLSerializer).serializeToString(svg);
  var dataURL = "data:image/svg+xml," + encodeURIComponent(svgAsXML);
  return dataURL;
}

button.onclick = function() {
  var svgElement = document.querySelector('svg');
  var svgWH = svgElement.getBBox();

  var canvasWidth = svgWH.width;
  var canvasHeight = svgWH.height;

  var groupElement = document.getElementById('fg');
  groupElement.setAttribute("transform", "translate(0,0)");

  const bb = groupElement.getBBox();

  //Title of the tree
  var svgimg = document.createElementNS('http://www.w3.org/2000/svg', 'image');
  svgimg.setAttributeNS(null, 'height', "30");
  svgimg.setAttributeNS(null, 'width', bb.width / 2);
  svgimg.setAttributeNS('http://www.w3.org/1999/xlink', 'href', 'http://localhost/images/Title3.png');
  svgimg.setAttributeNS(null, 'x', '-' + rectW / 2);
  svgimg.setAttributeNS(null, 'y', '-' + rectH / 2);
  svgimg.setAttributeNS(null, 'visibility', 'visible');

  //Background SVG pattern
  svgBgImg.style.backgroundImage = "url('http://localhost/images/background-F4EED7.svg')";

  // clone the svg to avoid destroying it while appending to the svg namespace
  let clonedGroupElement = groupElement.cloneNode(true);

  var svgContent = document.createElementNS('http://www.w3.org/2000/svg', 'svg');

  svgContent.setAttribute('viewBox', ' ' + bb.x + ' ' + bb.y + '  ' + bb.width + ' ' + bb.height);

  svgContent.setAttribute("width", "100%");
  svgContent.setAttribute("height", "100%");
  svgContent.setAttribute("preserveAspectRatio", "xMidYMid meet");

  // try to remove the information icon before downloading
  clonedGroupElement.querySelectorAll('[export-ignore]').forEach(function(node) {
    node.remove();
  });

  clonedGroupElement.style.borderImageSource = "url('http://localhost/images/border_1.svg')";
  clonedGroupElement.append(svgimg);
          clonedGroupElement.style.borderImageSource = "url('http://localhost/images/border_1.svg')";

  svgContent.appendChild(clonedGroupElement); // use the cloned nodes

  var dl = document.createElement('a');
  document.body.appendChild(dl);
  dl.setAttribute("href", svgDataURL(svgContent)); // function svgDataURL expects a node
  dl.setAttribute("download", "test.svg");
  dl.click();
  dl.remove();

  svgContent.removeChild(clonedGroupElement);
};

<style>.node {
  cursor: pointer;
}

.node circle {
  fill: #fff;
  stroke: steelblue;
  stroke-width: 1px;
}

.node text {
  font: 12px sans-serif;
}

.link {
  /*
      fill: none;
      stroke: #ccc;
      stroke-width: 2px;*/
}

</style>

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.4/d3.min.js"></script>
<html lang="en">

<head>
  <meta charset="utf-8">

  <title>Tree Example</title>
</head>

<body>

标签： javascripthtmlcsssvgbackground-image