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Last active Jun 4, 2018

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Map Pan & Zoom D3v4

D3 v4/5 version of mbostock's Map Pan & Zoom.

Demonstrates map panning and zooming using SVG transforms to avoid the overhead of reprojecting at every zoom iteration.

<head>
<style>
body {
margin: 0
}
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;
}
</style>
<script src="//d3js.org/d3.v5.min.js"></script>
<script src="//unpkg.com/topojson@3"></script>
</head>
<body>
<script>
const width = window.innerWidth;
const height = window.innerHeight;
const projection = d3.geoMercator()
.translate([width / 2, height / 2])
.scale((width - 1) / 2 / Math.PI);
const path = d3.geoPath()
.projection(projection);
const zoom = d3.zoom()
.scaleExtent([1, 8])
.on('zoom', zoomed);
const svg = d3.select('body').append('svg')
.attr('width', width)
.attr('height', height);
const g = svg.append('g');
svg.call(zoom);
d3.json('//unpkg.com/world-atlas@1/world/110m.json')
.then(world => {
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, (a, b) => a !== b))
.attr('class', 'boundary')
.attr('d', path);
});
function zoomed() {
g
.selectAll('path') // To prevent stroke width from scaling
.attr('transform', d3.event.transform);
}
</script>
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