Brush resize direction

This brush snaps to day boundaries. When the user releases the brush, the brush fires a brushend event, allowing a listener to adjust the brush extent. Using the new brush transitions released in D3 3.3, the brush smoothly interpolates from the original extent to the rounded extent. Compare this approach to using immediate snapping while brushing.

forked from mbostock's block: Brush resize direction

forked from anonymous's block: Brush resize direction

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

.axis text {
  font: 11px sans-serif;
}

.axis path {
  display: none;
}

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

.grid-background {
  fill: #ddd;
}

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

.grid .minor.tick line {
  stroke-opacity: .5;
}

.brush .extent {
  stroke: #000;
  fill-opacity: .125;
  shape-rendering: crispEdges;
}

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

var margin = {top: 200, right: 40, bottom: 200, left: 40},
    width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;

var x = d3.time.scale()
    .domain([new Date(2013, 7, 1), new Date(2013, 7, 15) - 1])
    .range([0, width]);

var brush = d3.svg.brush()
    .x(x)
    .extent([new Date(2013, 7, 2), new Date(2013, 7, 3)])
		.on("brushstart", onbrushstart)
    .on("brush", onbrush);
  
var startExtent = [];

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("rect")
    .attr("class", "grid-background")
    .attr("width", width)
    .attr("height", height);

svg.append("g")
    .attr("class", "x grid")
    .attr("transform", "translate(0," + height + ")")
    .call(d3.svg.axis()
        .scale(x)
        .orient("bottom")
        .ticks(d3.time.hours, 12)
        .tickSize(-height)
        .tickFormat(""))
  .selectAll(".tick")
    .classed("minor", function(d) { return d.getHours(); });

svg.append("g")
    .attr("class", "x axis")
    .attr("transform", "translate(0," + height + ")")
    .call(d3.svg.axis()
      .scale(x)
      .orient("bottom")
      .ticks(d3.time.days)
      .tickPadding(0))
  .selectAll("text")
    .attr("x", 6)
    .style("text-anchor", null);

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

gBrush.selectAll("rect")
    .attr("height", height);
  
function onbrushstart() {
  startExtent = brush.extent();
}

function onbrush() {
  console.log(d3.event)
  if (d3.event.type === "brush" && d3.event.mode === "resize") {
    var currentExtent = brush.extent();
    var side = (+currentExtent[0] !== +startExtent[0]) ? "left" : "right";
    
    console.log(side);
  }
}

</script>

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