Center a QuickDraw drawing by enjalot

index.html

<!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; }
  </style>
</head>

<body>
  <script>
    var width = 960;
    var height = 500;
    var scale = 1.25
    var delay = 1600
    var svg = d3.select("body").append("svg")
      .attr("width", width)
      .attr("height", height)
    .style("border", "1px solid #111")

    var line =  d3.line()
      .x(function(d) { return d.x })
      .y(function(d) { return d.y })
      .curve(d3.curveBasis)

    
		d3.json("https://storage.googleapis.com/fun-data/quickdraw/complex-faces.json", function(err, faces) {      
      
      render(0)
      function render(i) {
        var drawing = faces[i]
        var strokes = strokifyDrawing(drawing.drawing)
        center(strokes)

        var ps = svg.selectAll("path").data(strokes)
        ps.exit().remove()
        var psE = ps.enter().append("path")
        ps = psE.merge(ps)
        ps
        .attr("d", line)
        .style("fill", "none")
        .style("stroke", "#111")
        .style("stroke-width", 3)
        .style("stroke-linecap", "round")
        
        setTimeout(function() {
          i++
          console.log("i", i)
          if(i >= faces.length) i = 0;
          render(i)
        }, delay)
      }
      
		})
    
    
function center(strokes) {
 var minY = Infinity
  var maxY = -Infinity
  var minX = Infinity
  var maxX = -Infinity
  var centroidX = 0
  var centroidY = 0
  var count = 0
  strokes.forEach(function(stroke) {
    stroke.forEach(function(p) {
      centroidX += p.x
      centroidY += p.y
      count++
    })
  })
  centroidX /= count;
  centroidY /= count;
  strokes.forEach(function(stroke) {
    stroke.forEach(function(p) {
      p.x *= scale
      p.y *= scale
      p.x += width/2 - centroidX * scale
      p.y += height/2 - centroidY * scale
      if(p.y < minY) minY = p.y
      if(p.y > maxY) maxY = p.y
      if(p.x < minX) minX = p.x
      if(p.x > maxX) maxX = p.x
    })
  })
  var diffX = minX - (width - maxX)
  var diffY = minY - (height - maxY)
  strokes.forEach(function(stroke) {
    stroke.forEach(function(p) {
      p.x -= diffX/2
      p.y -= diffY/2
    })
  })
}


function strokifyDrawing(drawing) {
  var strokes = drawing.map(function(s) {
    var points = []
    s[0].forEach(function(x,i) {
      points.push({x: x, y: s[1][i] })
    })
    return points;
  })
  return strokes
}
  </script>
</body>