Zoomable Treemap v4 (overlay)

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
    
text {
  pointer-events: none;
}

.grandparent text {
  font-weight: bold;
}

rect {
  fill: none;
  stroke: #fff;
}

rect.parent,
.grandparent rect {
  stroke-width: 2px;
}

.grandparent rect {
  fill: orange;
}

.grandparent:hover rect {
  fill: #ee9700;
}

.children rect.parent,
.grandparent rect {
  cursor: pointer;
}

.children rect.parent {
  fill: #bbb;
  fill-opacity: .5;
}

.children:hover rect.child {
  fill: #bbb;
}
  </style>
</head>

<body>
  <p id="chart">
Sample zoomable treemap
</p>
<div id="domainDrillDown"></div>
  <script>
var data = {
  "name": 'Sample',
  "shortName": 'Sample',
  "children": [
    {
      "name": "6.1 Identify and plan learning needs",
      "shortName": "AITSL-A61",
      "size": null,
      "children": [
        {
          "name": "Analyse the Standards for.",
          "shortName": "AITSL-A61-H",
          "size": 59,
          "children": [
            
          ]
        },
        {
          "name": "Demonstrate an  of the role of the",
          "shortName": "AITSL-A61-G",
          "size": 448,
          "children": [
            
          ]
        },
        {
          "name": "Use  knowledge of the Standards for ",
          "shortName": "AITSL-A61-L",
          "size": 59,
          "children": [
            
          ]
        },
        {
          "name": "Use the  plan learning needs.",
          "shortName": "AITSL-A61-P",
          "size": 101,
          "children": [
            
          ]
        }
      ]
    },
    {
      "name": "6.2 Engage in improve practice",
      "shortName": "AITSL-A62",
      "size": null,
      "children": [
        {
          "name": "Participate in to update knowledge .",
          "shortName": "AITSL-A62-P",
          "size": 92,
          "children": [
            
          ]
        },
        {
          "name": "Understand appropriate sources of .",
          "shortName": "AITSL-A62-G",
          "size": 405,
          "children": [
            
          ]
        },
        {
          "name": "Plan for  and critiquing ",
          "shortName": "AITSL-A62-H",
          "size": 49,
          "children": [
            
          ]
        },
        {
          "name": "Initiate to expand opportunities.",
          "shortName": "AITSL-A62-L",
          "size": 47,
          "children": [
            
          ]
        }
      ]
    },
    {
      "name": "6.3 Engage with  and improve practice",
      "shortName": "AITSL-A63",
      "size": null,
      "children": [
        {
          "name": "Contribute to collegial  and apply.",
          "shortName": "AITSL-A63-P",
          "size": 84,
          "children": [
            
          ]
        },
        {
          "name": "Initiate and engage in  discussions.",
          "shortName": "AITSL-A63-H",
          "size": 51,
          "children": [
            
          ]
        },
        {
          "name": "Seek and feedback from .",
          "shortName": "AITSL-A63-G",
          "size": 458,
          "children": [
            
          ]
        },
        {
          "name": "Implement  dialogue within   by .",
          "shortName": "AITSL-A63-L",
          "size": 40,
          "children": [
            
          ]
        }
      ]
    },
    {
      "name": "6.4 Apply  improve learning",
      "shortName": "AITSL-A64",
      "size": null,
      "children": [
        {
          "name": "Undertake  .",
          "shortName": "AITSL-A64-P",
          "size": 76,
          "children": [
            
          ]
        },
        {
          "name": "Demonstrate an  of the rationale.",
          "shortName": "AITSL-A64-G",
          "size": 426,
          "children": [
            
          ]
        },
        {
          "name": "Engage with  to evaluate the .",
          "shortName": "AITSL-A64-H",
          "size": 54,
          "children": [
            
          ]
        },
        {
          "name": "Advocate,  in and lead high-quality .",
          "shortName": "AITSL-A64-L",
          "size": 43,
          "children": [
            
          ]
        }
      ]
    }
  ]
};

//https://bl.ocks.org/JacquesJahnichen/42afd0cde7cbf72ecb81
//https://bl.ocks.org/ganeshv/6a8e9ada3ab7f2d88022
//https://gist.github.com/tkafka/6d00c44d5ae52182f548a18e8db44811
var margin = {top: 20, right: 0, bottom: 0, left: 0},
width = 640, //640
height = 530,
formatNumber = d3.format(",d"),
transitioning;

var x = d3.scaleLinear()
.domain([0, width])
.range([0, width]);

var y = d3.scaleLinear()
.domain([0, height - margin.top - margin.bottom])
.range([0, height - margin.top - margin.bottom]);

var color = d3.scaleOrdinal()
.range(d3.schemeCategory10
    .map(function(c) { c = d3.rgb(c); c.opacity = 0.6; return c; }));

//var color = d3.scaleOrdinal(d3.schemeCategory20.map(fader));

var fader = function(color) { return d3.interpolateRgb(color, "#fff")(0.2); };

var format = d3.format(",d");

var treemap;

var svg, grandparent;

updateDrillDown();

function updateDrillDown() {
	
	if (svg) {
		svg.selectAll("*").remove();
	} else {

//		 var treemap = d3.layout.treemap()
//	      .children(function(d, depth) { return depth ? null : d._children; })
//	      .sort(function(a, b) { return a.value - b.value; })
//	      .ratio(height / width * 0.5 * (1 + Math.sqrt(5)))
//	      .round(false);
	  
	  svg = d3.select("#domainDrillDown").append("svg")
	      .attr("width", width - margin.left - margin.right)
	      .attr("height", height - margin.bottom - margin.top)
	      .style("margin-left", -margin.left + "px")
	      .style("margin.right", -margin.right + "px")
	    .append("g")
	      .attr("transform", "translate(" + margin.left + "," + margin.top + ")")
	      .style("shape-rendering", "crispEdges");		
		
		
		 
		  grandparent = svg.append("g")
		      .attr("class", "grandparent");
		  
		  grandparent.append("rect")
		      .attr("y", -margin.top)
		      .attr("width", width)
		      .attr("height", margin.top);
		  
		  grandparent.append("text")
		      .attr("x", 6)
		      .attr("y", 6 - margin.top)
		      .attr("dy", ".75em");		 
		 
		 treemap = d3.treemap()
		    //.tile(d3.treemapResquarify)
		    .size([width, height])
		    .round(false)
		    .paddingInner(1);
	}
				  
		  var root = d3.hierarchy(data)
		      .eachBefore(function(d) { d.id = (d.parent ? d.parent.id + "." : "") + d.data.shortName; })
		      .sum((d) => d.size)
		      .sort(function(a, b) {
		      console.log('initial root sort a ' + a.value + ' b ' + b.value);
		        return b.height - a.height || b.value - a.value; });
		  
		  initialize(root);
		  accumulate(root);
		  layout(root);
		  treemap(root);
		  display(root);

};

function initialize(root) {
    root.x = root.y = 0;
    root.x1 = width;
    root.y1 = height;
    root.depth = 0;
  }

// Aggregate the values for internal nodes. This is normally done by the
  // treemap layout, but not here because of our custom implementation.
  // We also take a snapshot of the original children (_children) to avoid
  // the children being overwritten when when layout is computed.
  function accumulate(d) {
	  console.log('accumulate called ' + d.data.name);
    return (d._children = d.children)
        ? d.value = d.children.reduce(function(p, v) { return p + accumulate(v); }, 0)
        : d.value;
  }

// Compute the treemap layout recursively such that each group of siblings
// uses the same size (1×1) rather than the dimensions of the parent cell.
// This optimizes the layout for the current zoom state. Note that a wrapper
// object is created for the parent node for each group of siblings so that
// the parent’s dimensions are not discarded as we recurse. Since each group
// of sibling was laid out in 1×1, we must rescale to fit using absolute
// coordinates. This lets us use a viewport to zoom.
function layout(d) {
  if (d._children) {
//    treemap.nodes({_children: d._children});
//	  treemap(d);
    d._children.forEach(function(c) {
      c.x0 = d.x0 + c.x0 * d.x1;
      c.y0 = d.y0 + c.y0 * d.y1;
      c.x1 *= d.x1;
      c.y1 *= d.y1;
      c.parent = d;
      layout(c);
    });
  }
}

function display(d) {
	
  grandparent
      .datum(d.parent)
      .on("click", transition)
    .select("text")
      .text(name(d));

var g1 = svg.insert("g", ".grandparent")
      .datum(d)
      .attr("class", "depth");
  
  var g = g1.selectAll("g")
      .data(d._children)
    .enter().append("g");

g.filter(function(d) { return d._children; })
      .classed("children", true)
      .on("click", transition);

var children = g.selectAll(".child")
      .data(function(d) { return d._children || [d]; })
    .enter().append("g");

children.append("rect")
      .attr("class", "child")
      .call(rect)
    .append("title")
      .text(function(d) { return d.data.shortName + " (" + formatNumber(d.value) + ")"; });

children.append("text")
      .attr("class", "ctext")
      .text(function(d) { return d.data.shortName; })
      .call(text2);

g.append("rect")
      .attr("class", "parent")
      .call(rect);

function transition(d) {
    if (transitioning || !d) return;
    transitioning = true;

var g2 = display(d),
        t1 = g1.transition().duration(750),
        t2 = g2.transition().duration(750);

// Update the domain only after entering new elements.
    x.domain([d.x0, d.x0 + d.x1]);
    y.domain([d.y0, d.y0 + d.y1]);

// Enable anti-aliasing during the transition.
    svg.style("shape-rendering", null);

// Draw child nodes on top of parent nodes.
    svg.selectAll(".depth").sort(function(a, b) { 
    	console.log('.depth sort a ' + a.depth + ' b ' + b.depth);
    	return a.depth - b.depth; });

// Fade-in entering text.
    g2.selectAll("text").style("fill-opacity", 0);

// Transition to the new view.
    t1.selectAll("text").call(text).style("fill-opacity", 0);
    t2.selectAll("text").call(text).style("fill-opacity", 1);
    t1.selectAll("rect").call(rect);
    t2.selectAll("rect").call(rect);

// Remove the old node when the transition is finished.
    t1.remove().on("end", function() {
      svg.style("shape-rendering", "crispEdges");
      transitioning = false;
    });
  }

return g;
}

function name(d) {
    return d.parent
        ? name(d.parent) + " / " + d.data.shortName + " (" + formatNumber(d.value) + ")"
        : d.data.shortName + " (" + formatNumber(d.value) + ")";
  }

</script>
</body>

https://d3js.org/d3.v4.min.js