Brush Handles

This example demonstrates how to add visible and draggable handles to D3’s d3.svg.brush component, rather than that relying on the invisible boundary of the brush extent. The handle sizes here are exaggerated for demonstration purposes!

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

svg {
  font: 10px sans-serif;
}

circle {
  -webkit-transition: fill-opacity 250ms linear;
}

.selecting circle {
  fill-opacity: .2;
}

.selecting circle.selected {
  stroke: #f00;
}

.resize path {
  fill: #666;
  fill-opacity: .8;
  stroke: #000;
  stroke-width: 1.5px;
}

.axis path, .axis line {
  fill: none;
  stroke: #000;
  shape-rendering: crispEdges;
}

.brush .extent {
  fill-opacity: .125;
  shape-rendering: crispEdges;
  pointer-events:none;
}

</style>
<body>
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script>
<script>

var data = d3.range(800).map(Math.random);

var margin = {top: 194, right: 50, bottom: 214, left: 50},
    width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;

var x = d3.scale.linear()
    .range([0, width]);

var y = d3.random.normal(height / 2, height / 8);

var brush = d3.svg.brush()
    .x(x)
    .extent([.3, .5])
    .on("brushstart", brushstart)
    .on("brush", brushmove)
    .on("brushend", brushend);

var arc = d3.svg.arc()
    .outerRadius(height / 2)
    .startAngle(0)
    .endAngle(function(d, i) { return i ? -Math.PI : Math.PI; });

var svg = d3.select("body").append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
  .append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

svg.append("g")
    .attr("class", "x axis")
    .attr("transform", "translate(0," + height + ")")
    .call(d3.svg.axis().scale(x).orient("bottom"));

var circle = svg.append("g").selectAll("circle")
    .data(data)
  .enter().append("circle")
    .attr("transform", function(d) { return "translate(" + x(d) + "," + y() + ")"; })
    .attr("r", 3.5);

var brushg = svg.append("g")
    .attr("class", "brush")
    .call(brush);

brushg.selectAll(".resize").append("path")
    .attr("transform", "translate(0," +  height / 2 + ")")
    .attr("d", arc);

brushg.selectAll("rect")
    .attr("height", height);

brushstart();
brushmove();

function brushstart() {
  svg.classed("selecting", true);
}

function brushmove() {
  var s = brush.extent();
  circle.classed("selected", function(d) { return s[0] <= d && d <= s[1]; });
}

function brushend() {
  svg.classed("selecting", !d3.event.target.empty());
}

</script>

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js