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Map Pan & Zoom II
license: gpl-3.0

This example uses d3.behavior.zoom with a dynamic projection for map panning and zooming. This approach is slower than using a transform or transforming pre-projected geometry because it requires reprojecting whenever the zoom changes.

<!DOCTYPE html>
<meta charset="utf-8">
<style>
svg {
background: #eee;
}
.sphere {
fill: #fff;
}
.land {
fill: #000;
}
.boundary {
fill: none;
stroke: #fff;
stroke-linejoin: round;
stroke-linecap: round;
vector-effect: non-scaling-stroke;
}
.overlay {
fill: none;
pointer-events: all;
}
</style>
<script src="//d3js.org/d3.v3.min.js"></script>
<script src="//d3js.org/topojson.v1.min.js"></script>
<body>
<script>
var width = 960,
height = 960,
scale0 = (width - 1) / 2 / Math.PI;
var projection = d3.geo.mercator();
var zoom = d3.behavior.zoom()
.translate([width / 2, height / 2])
.scale(scale0)
.scaleExtent([scale0, 8 * scale0])
.on("zoom", zoomed);
var path = d3.geo.path()
.projection(projection);
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height)
.append("g");
var g = svg.append("g");
svg.append("rect")
.attr("class", "overlay")
.attr("width", width)
.attr("height", height);
svg
.call(zoom)
.call(zoom.event);
d3.json("/mbostock/raw/4090846/world-110m.json", function(error, world) {
if (error) throw error;
g.append("path")
.datum({type: "Sphere"})
.attr("class", "sphere")
.attr("d", path);
g.append("path")
.datum(topojson.merge(world, world.objects.countries.geometries))
.attr("class", "land")
.attr("d", path);
g.append("path")
.datum(topojson.mesh(world, world.objects.countries, function(a, b) { return a !== b; }))
.attr("class", "boundary")
.attr("d", path);
});
function zoomed() {
projection
.translate(zoom.translate())
.scale(zoom.scale());
g.selectAll("path")
.attr("d", path);
}
d3.select(self.frameElement).style("height", height + "px");
</script>
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