README.md

## README.md

      
        

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              README.md
            
          
        
      
    
  
    An example of setting x- and y-scale domains (zooming) by selecting a
rectangular region using the mouse.  The original question required that it
work in tandem with d3.behavior.zoom for panning, hence the checkbox for
switching on the “zoom by rectangle” mode.

  

  

## index.html
<!DOCTYPE html>
<meta charset="utf-8">
<title>Zoom by Rectangle</title>
<script src="http://d3js.org/d3.v2.min.js?2.10.1"></script>
<style>

body {
  font-family: sans-serif;
}

.noselect {
  -webkit-touch-callout: none;
  -webkit-user-select: none;
  -khtml-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  user-select: none;
}

svg {
  font: 10px sans-serif;
  shape-rendering: crispEdges;
}

rect {
  fill: #ddd;
}

rect.zoom {
  stroke: steelblue;
  fill-opacity: 0.5;
}

.axis path, .axis line {
  fill: none;
  stroke: #fff;
}

</style>
<p><label for="zoom-rect"><input type="checkbox" id="zoom-rect"> zoom by rectangle</label>
<script>

var margin = {top: 0, right: 12, bottom: 12, left: 36},
    width = 960 - margin.left - margin.right,
    height = 430 - margin.top - margin.bottom;

var x = d3.scale.linear()
    .domain([-width / 2, width / 2])
    .range([0, width]);

var y = d3.scale.linear()
    .domain([-height / 2, height / 2])
    .range([height, 0]);

var xAxis = d3.svg.axis()
    .scale(x)
    .orient("bottom")
    .tickSize(-height);

var yAxis = d3.svg.axis()
    .scale(y)
    .orient("left")
    .ticks(5)
    .tickSize(-width);

var zoom = d3.behavior.zoom().x(x).y(y).on("zoom", refresh);

var zoomRect = false;

d3.select("#zoom-rect").on("change", function() {
      zoomRect = this.checked;
    });

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 + ")")
    .call(zoom)
  .append("g")
    .on("mousedown", function() {
      if (!zoomRect) return;
      var e = this,
          origin = d3.mouse(e),
          rect = svg.append("rect").attr("class", "zoom");
      d3.select("body").classed("noselect", true);
      origin[0] = Math.max(0, Math.min(width, origin[0]));
      origin[1] = Math.max(0, Math.min(height, origin[1]));
      d3.select(window)
          .on("mousemove.zoomRect", function() {
            var m = d3.mouse(e);
            m[0] = Math.max(0, Math.min(width, m[0]));
            m[1] = Math.max(0, Math.min(height, m[1]));
            rect.attr("x", Math.min(origin[0], m[0]))
                .attr("y", Math.min(origin[1], m[1]))
                .attr("width", Math.abs(m[0] - origin[0]))
                .attr("height", Math.abs(m[1] - origin[1]));
          })
          .on("mouseup.zoomRect", function() {
            d3.select(window).on("mousemove.zoomRect", null).on("mouseup.zoomRect", null);
            d3.select("body").classed("noselect", false);
            var m = d3.mouse(e);
            m[0] = Math.max(0, Math.min(width, m[0]));
            m[1] = Math.max(0, Math.min(height, m[1]));
            if (m[0] !== origin[0] && m[1] !== origin[1]) {
              zoom.x(x.domain([origin[0], m[0]].map(x.invert).sort()))
                  .y(y.domain([origin[1], m[1]].map(y.invert).sort()));
            }
            rect.remove();
            refresh();
          }, true);
      d3.event.stopPropagation();
    });

svg.append("rect")
    .attr("width", width)
    .attr("height", height);

svg.append("g")
    .attr("class", "x axis")
    .attr("transform", "translate(0," + height + ")")
    .call(xAxis);

svg.append("g")
    .attr("class", "y axis")
    .call(yAxis);

function refresh() {
  svg.select(".x.axis").call(xAxis);
  svg.select(".y.axis").call(yAxis);
}

</script>