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@Andrew-Reid
Created November 15, 2018 21:29
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<html>
<head>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script src="https://d3js.org/d3-tile.v0.0.min.js"></script>
<script src="https://unpkg.com/topojson@3"></script>
</head>
<body>
<div id="mapplaceholder"></div>
<script>
var map;
var width = 800,
height = 600;
var pi = Math.PI,
tau = 2 * pi;
var projection = d3.geoMercator()
.scale(1 / tau)
.translate([0, 0]);
var path = d3.geoPath()
.projection(projection);
map = d3.select("#mapplaceholder")
.append("svg")
.attr("width", width)
.attr("height", height);
var tile = d3.tile()
.size([width, height]);
var zoom = d3.zoom()
.scaleExtent([1 << 15, 1 << 30])
.on("zoom", zoomed);
var raster = map.append("g");
var vector;
d3.json('data.json', function (error, data) {
if (error) throw error;
var topo = topojson.topology({foo: data});
vector = map.selectAll("path")
.data(topojson.feature(topo, topo.objects.foo).features)
.enter()
.append("path");
var center = projection([36.8, -2.3]);
map
.call(zoom)
.call(zoom.transform, d3.zoomIdentity
.translate(width / 2, height / 2)
.scale(1 << 19)
.translate(-center[0], -center[1]));
});
function zoomed(){
var transform = d3.event.transform;
var tiles = tile
.scale(transform.k)
.translate([transform.x, transform.y])
();
projection
.scale(transform.k / tau)
.translate([transform.x, transform.y]);
vector
.attr("d", path);
var image = raster
.attr("transform", stringify(tiles.scale, tiles.translate))
.selectAll("image")
.data(tiles, function(d) { return d; });
image.exit().remove();
image.enter().append("image")
.attr("xlink:href", function(d) { return "http://" + "abc"[d[1] % 3] + ".tile.openstreetmap.org/" + d[2] + "/" + d[0] + "/" + d[1] + ".png"; })
.attr("x", function(d) { return d[0] * 256; })
.attr("y", function(d) { return d[1] * 256; })
.attr("width", 256)
.attr("height", 256);
}
function stringify(scale, translate) {
var k = scale / 256, r = scale % 1 ? Number : Math.round;
return "translate(" + r(translate[0] * scale) + "," + r(translate[1] * scale) + ") scale(" + k + ")";
}
</script>
</body>
</html>
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