D3 Examples - Combining Canvas + SVG for Retina

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<!DOCTYPE html>
<head>
<meta charset="utf-8">
<style>
  /* to prevent browser overscrolling */
  html {
    overflow: hidden;
  }
​
  body {
    margin: 0; /* or else canvas alignment is off */
    box-sizing: border-box;
  }
​
  /* for retina display */
  canvas {
    width: 880px;
    height: 450px;
  }
​
  .chart {
    position: absolute;
  }
​
  #chart-canvas {
      margin: 20px 0 0 60px;
      z-index: 1;
  }
​
  #axis-svg {
      z-index: 2;
  }
​
  .area {
    clip-path: url(#clip);
  }
​
  .zoom {
    cursor: move;
    fill: none;
    pointer-events: all;
  }
​
  .PVkW  {
      fill: #f29e2e;
    }
​
  .TBLkW  {
      fill: #36aeaf;
    }
</style>
</head>
<body>
  <canvas width="1760" height="900" id="chart-canvas" class="chart"></canvas>
  <svg width="960" height="500" id="axis-svg" class="chart"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script><script>
​
var svg = d3.select("svg"),
    margin = {top: 20, right: 20, bottom: 30, left: 60},
    width = +svg.attr("width") - margin.left - margin.right,
    height = +svg.attr("height") - margin.top - margin.bottom,
    g = svg.append("g").attr("transform", "translate(" + margin.left + "," + margin.top + ")");
​
var canvas = document.querySelector("canvas"),
    context = canvas.getContext("2d"),
    canvasScale = canvas.width / width;
​
var parseDate = d3.timeParse("%Y/%m/%d %H:%M");
​
var color = d3.scaleOrdinal()
  .domain(["PVkW", "TBLkW"])
  .range(["rgba(249, 208, 87, 1.0)", "rgba(54, 174, 175, 0.6)"]);
​
var xSVG = d3.scaleTime()
    .range([0, width]);
​
var x = d3.scaleTime()
    .range([0, width]);
​
var x2 = d3.scaleTime()   // for zooming
    .range([0, width]);
​
var ySVG = d3.scaleLinear()
    .range([height, 0]);
​
var y = d3.scaleLinear()
    .range([height, 0]);
​
var xAxisSVG = d3.axisBottom(xSVG);
​
var yAxisSVG = d3.axisLeft(ySVG);
​
var area = d3.area()
    .x(function(d) { return x(d.date); })
    .y0(y(0))
    .y1(function(d) { return y(d.kW); })
    .curve(d3.curveStep)
    .context(context);
​
var yGroupSVG = g.append("g")
    .attr("class", "y-axis");
​
var xGroupSVG = g.append("g")
    .attr("transform", "translate(0," + height + ")")
    .attr("class", "x-axis");
​
var defs = svg.append("defs");
​
defs.append("clipPath")
    .attr("id", "clip")
    .append("rect")
    .attr("width", width)
    .attr("height", height);
​
  d3.csv("kW.csv", type, function(error, data) {
    if (error) throw error;
​
    var sources = data.columns.slice(1).map(function(id) {
      return {
        id: id,
        values: data.map(function(d) {
          return {date: d.date, kW: d[id]};
        })
      };
    });
​
  var len = sources.length;
​
  var xExtent = d3.extent(data, function(d) { return d.date; });
  xSVG.domain(xExtent);
  x.domain(xExtent);
  x2.domain(x.domain());
  ySVG.domain([
    0,
    d3.max(sources, function(c) { return d3.max(c.values, function(v) { return v.kW; }); })
  ]);
  y.domain([
    0,
    d3.max(sources, function(c) { return d3.max(c.values, function(v) { return v.kW; }); })
  ]);
  yGroupSVG.call(yAxisSVG);
  xGroupSVG.call(xAxisSVG);
  color.domain(sources.map(function(c) { return c.id; }));
​
function draw() {
  context.save();
  context.scale(canvasScale, canvasScale);
  context.clearRect(0, 0, width, height);
​
   // clip path
   context.beginPath()
   context.rect(0, 0, width, height);
   context.clip();
​
   for (i=0; i<len; i++) {
     context.beginPath();
     area(sources[i].values);
     context.fillStyle = color(sources[i].id);
     context.fill();
   }
​
   context.restore();
}
​
 draw();
​
 var zoom = d3.zoom()
     .scaleExtent([1, Infinity])
     .translateExtent([[0, 0], [width, height]])
     .extent([[0, 0], [width, height]])
     .on("zoom", zoomed);
​
 var zoomRect = svg.append("rect")
     .attr("width", width)
     .attr("height", height)
     .attr("transform", "translate(" + margin.left + "," + margin.top + ")")
     .attr("fill", "none")
     .attr("pointer-events", "all")
     .call(zoom)
            .on("dblclick.zoom", null);
​
 function zoomed() {
   var t = d3.event.transform;
   var xz = t.rescaleX(xSVG);
   xGroupSVG.call(xAxisSVG.scale(xz));
   x = t.rescaleX(x2);
   draw();
 }
});
​
function type(d, _, columns) {
  d.date = parseDate(d.date);
  for (var i = 1, n = columns.length, c; i < n; ++i) d[c = columns[i]] = +Math.round(d[c]);
  return d;
}
​
</script>
</body>
</html>
​
    