D3 Examples - Zoom to Bounding Box with translateExtent

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<!DOCTYPE html>
<meta charset="utf-8">
<style>
​
  * {
    box-sizing: border-box;
  }
  
  svg {
    border: 1px solid;
  }
  
.background {
  fill: none;
  pointer-events: all;
}
​
.feature {
  fill: #ccc;
  cursor: pointer;
}
​
.feature.active {
  fill: orange;
}
​
.mesh {
  fill: none;
  stroke: #fff;
  stroke-linecap: round;
  stroke-linejoin: round;
}
​
</style>
<body>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script src="https://d3js.org/topojson.v2.min.js"></script>
<script>
  
  
  
  var width = 960,
  height = 500,
  active = d3.select(null);
​
var projection = d3.geoAlbersUsa() // updated for d3 v4
​
var zoom = d3.zoom()
  .extent([
    [0, 0],
    [width, height]
  ])
  .translateExtent([
    [0, 0],
    [width, height]
  ])
  .scaleExtent([1, 8])
  .on("zoom", zoomed);
​
var path = d3.geoPath() // updated for d3 v4
  .projection(projection);
​
var svg = d3.select("body").append("svg")
  .attr("width", width)
  .attr("height", height)
  .on("click", stopped, true);
​
svg.append("rect")
  .attr("class", "background")
  .attr("width", width)
  .attr("height", height)
  .on("click", reset);
​
var g = svg.append("g");
​
svg
  .call(zoom); // delete this line to disable free zooming
// .call(zoom.event); // not in d3 v4
​
d3.json("/../../data/us.json", function(error, usa) {
  if (error) throw error;
​
​
​
  var us = topojson.mesh(usa, usa.objects.states);
​
  projection.fitSize([width, height], us);
​
  g.selectAll("path")
    .data(topojson.feature(usa, usa.objects.states).features)
    .enter().append("path")
    .attr("d", path)
    .attr("class", "feature")
    .on("click", clicked);
​
  g.append("path")
    .datum(us)
    .attr("class", "mesh")
    .attr("d", path);
});
​
function clicked(d) {
  if (active.node() === this) return reset();
  active.classed("active", false);
  active = d3.select(this).classed("active", true);
​
  var bounds = path.bounds(d),
    dx = bounds[1][0] - bounds[0][0],
    dy = bounds[1][1] - bounds[0][1],
    x = (bounds[0][0] + bounds[1][0]) / 2,
    y = (bounds[0][1] + bounds[1][1]) / 2,
    scale = Math.max(1, Math.min(8, .9 / Math.max(dx / width, dy / height))),
    translate = [width / 2 - scale * x, height / 2 - scale * y];
​
  svg.transition()
    .duration(750)
    .call(zoom.transform, d3.zoomIdentity.translate(translate[0], translate[1]).scale(scale)); // updated for d3 v4
}
​
function reset() {
  active.classed("active", false);
  active = d3.select(null);
​
  svg.transition()
    .duration(750)
    // .call( zoom.transform, d3.zoomIdentity.translate(0, 0).scale(1) ); // not in d3 v4
    .call(zoom.transform, d3.zoomIdentity); // updated for d3 v4
}
​
function zoomed() {
  g.style("stroke-width", 1.5 / d3.event.transform.k + "px");
  // g.attr("transform", "translate(" + d3.event.translate + ")scale(" + d3.event.scale + ")"); // not in d3 v4
  g.attr("transform", d3.event.transform); // updated for d3 v4
}
​
// If the drag behavior prevents the default click,
// also stop propagation so we don’t click-to-zoom.
function stopped() {
  if (d3.event.defaultPrevented) d3.event.stopPropagation();
}
</script>
</body>
    