WWSD #13: d3 + Canvas

Working with spatial data

Example #13

Rendering maps with d3 and Canvas

forked from mbostock's block: U.S. Counties TopoJSON

forked from enjalot's block: WWSD #12: d3 + TopoJSON

<!DOCTYPE html>
<meta charset="utf-8">
<style>

path {
  fill: #ccc;
  stroke: #fff;
  stroke-width: .5px;
}

path:hover {
  fill: red;
}

</style>
<body>
  <canvas></canvas>
<script src="//d3js.org/d3.v3.min.js"></script>
<script src="//d3js.org/topojson.v1.min.js"></script>
<script>

var width = 960,
    height = 500;

var canvas = d3.select("canvas").node()
canvas.width = width;
canvas.height = height;
var ctx = canvas.getContext('2d')
var path = d3.geo.path()
  .context(ctx)

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

var url = "https://gist.githubusercontent.com/mbostock/4090846/raw/d534aba169207548a8a3d670c9c2cc719ff05c47/us.json"
d3.json(url, function(error, topology) {
  if (error) throw error;
  
  console.log("topojson", topology)
  var geojson = topojson.feature(topology, topology.objects.counties);
  console.log("geojson", geojson)

ctx.strokeStyle = "#111";
  ctx.fillStyle = "#99ffe8"
  geojson.features.forEach(function(feature) {
    ctx.beginPath()
    path(feature)
    ctx.fill()
    ctx.stroke();
  })
});

</script>

https://d3js.org/d3.v3.min.js

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