Country Labels using d3fc-label-layout

Links: https://stackoverflow.com/questions/45107825/how-to-use-d3fc-label-label-js-on-a-map https://stackoverflow.com/questions/17425268/d3js-automatic-labels-placement-to-avoid-overlaps-force-repulsion

https://bl.ocks.org/ColinEberhardt/389c76c6a544af9f0cab https://bost.ocks.org/mike/map/ (v3 version)

/pnavarrc/5913636 - label placement using the force layout and multiple foci but v3 https://bl.ocks.org/mbostock/1667139 - force layout in d3v4

/larskotthoff/11406992 - implements automatic label placement using collision detection

Other: https://github.com/migurski/Dymo https://github.com/ShareMap/ShareMap-dymo-js

/ilyabo/2585241 http://jsfiddle.net/s3logic/j789j3xt/

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" \>
<style>
  path {
    stroke: white;
    stroke-width: 1.5px;
    fill: #C4C4C4;
  }
    text {
      font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
      font-size: 14px;
      pointer-events: none;
    }

.label rect {
        fill: transparent;
    }  
</style>
<script src="https://d3js.org/d3.v4.min.js"></script>
  
  <script src="https://unpkg.com/topojson-client@3"></script>
<script src="https://npmcdn.com/d3fc-label-layout@4.0.0/build/d3fc-label-layout.js"></script>
<script src="https://npmcdn.com/d3fc-data-join@2.0.0/build/d3fc-data-join.js"></script>
<script src="https://npmcdn.com/d3fc-rebind@4.0.1/build/d3fc-rebind.js"></script>
  <script src="https://d3js.org/queue.v1.min.js"></script>
</head>

<body>
<div id="map"></div>
  <script>
    const map = d3.select("#map");
    const width = map.node().getBoundingClientRect().width;
    const height = width / 2;

const projection = d3.geoMercator(); 
    const path = d3.geoPath().projection(projection).pointRadius(2);
    
    const zoom = d3.zoom()
    .scaleExtent([1, 40])
    .translateExtent([[0,0], [width, height]])
    .extent([[0, 0], [width, height]])
    .on("zoom", zoomed);

const svg = map.append("svg")
    .attr("width", width)
    .attr("height", height)
    .call(zoom);
    
    const g = svg.append("g");

queue()
    .defer(d3.json, "https://cdn.rawgit.com/mbostock/4090846/raw/d534aba169207548a8a3d670c9c2cc719ff05c47/world-50m.json")
    .defer(d3.tsv, "https://cdn.rawgit.com/mbostock/4090846/raw/d534aba169207548a8a3d670c9c2cc719ff05c47/world-country-names.tsv")
    .await(ready);
  
function ready(error, world, names) {
  if (error) throw error;

var countries = topojson.feature(world, world.objects.countries).features;

//map country names to IDs used on map
  var names_arr=[];
  names.forEach(function(i){
    names_arr[i.id]=i.name;
  });
  
  
      countries.forEach(function(feature) {
        //feature.properties.area = d3.geoArea(feature);
        //feature.properties.center = projection(d3.geoCentroid(feature));
        feature.properties.name = names_arr[feature.id];
      });

// "path" instead of ".subunit"
  g.selectAll("path")
    //.data(map_data.features)
  .data(countries)
  .enter().append("path")
    .attr("d", path)
    .attr("class", function(d) { return "label " + d.id})

/*
     g.selectAll(".subunit-label")
      .data(countries)
    .enter().append("text")
      .attr("class", function(d) { return "subunit-label " + d.id; })
      .attr("transform", function(d) { return "translate(" + path.centroid(d) + ")"; })
      .attr("dy", ".35em")
      .text(function(d) { return d.properties.name; });
  
  
    
  */
  var labelPadding = 2;

// the component used to render each label
  var textLabel = fc.layoutTextLabel()
    .padding(labelPadding)
    //.value(function(d) { return map_data.properties.iso; });
    //.value(function(d) { return d.properties.iso; });
    .value(function(d) { return d.properties.name; });

// use simulate annealing to find minimum overlapping text label positions
  //https://github.com/d3fc/d3fc-label-layout/blob/master/README.md
  var strategy = fc.layoutGreedy();
  //var strategy = fc.layoutAnnealing();

// create the layout that positions the labels
  var labels = fc.layoutLabel(strategy)
      .size(function(_, i, g) {
          // measure the label and add the required padding
          var textSize = d3.select(g[i])
              .select('text')
              .node()
              .getBBox();
          return [textSize.width + labelPadding * 2, textSize.height + labelPadding * 2];
      })
      .position(function(d) { return path.centroid(d); })
      .component(textLabel);

// render!
  g.datum(countries)
       .call(labels);  
  
  
  
  
  
  
  
  
  
  
  
};

function zoomed(){
  g.attr("transform", d3.event.transform);
}  
  </script>
</body>
</html>

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

https://d3js.org/topojson.v2.min.js

https://unpkg.com/topojson-client@3

https://npmcdn.com/d3fc-label-layout@4.0.0/build/d3fc-label-layout.js

https://npmcdn.com/d3fc-data-join@2.0.0/build/d3fc-data-join.js

https://npmcdn.com/d3fc-rebind@4.0.1/build/d3fc-rebind.js

https://d3js.org/queue.v1.min.js