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| license: gpl-3.0 |
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| // Derived from https://github.com/d3/d3-plugins/blob/master/geo/tile/tile.js | |
| d3.geoTile = function() { | |
| var size = [960, 500], | |
| scale = 256, | |
| translate = [size[0] / 2, size[1] / 2], | |
| zoomDelta = 0; | |
| function tile() { | |
| var z = Math.max(Math.log(scale) / Math.LN2 - 8, 0), | |
| z0 = Math.round(z + zoomDelta), | |
| k = Math.pow(2, z - z0 + 8), | |
| origin = [(translate[0] - scale / 2) / k, (translate[1] - scale / 2) / k], | |
| tiles = [], | |
| cols = d3.range(Math.max(0, Math.floor(-origin[0])), Math.max(0, Math.ceil(size[0] / k - origin[0]))), | |
| rows = d3.range(Math.max(0, Math.floor(-origin[1])), Math.max(0, Math.ceil(size[1] / k - origin[1]))); | |
| rows.forEach(function(y) { | |
| cols.forEach(function(x) { | |
| tiles.push([x, y, z0]); | |
| }); | |
| }); | |
| tiles.translate = origin; | |
| tiles.scale = k; | |
| return tiles; | |
| } | |
| tile.size = function(_) { | |
| if (!arguments.length) return size; | |
| size = _; | |
| return tile; | |
| }; | |
| tile.scale = function(_) { | |
| if (!arguments.length) return scale; | |
| scale = _; | |
| return tile; | |
| }; | |
| tile.translate = function(_) { | |
| if (!arguments.length) return translate; | |
| translate = _; | |
| return tile; | |
| }; | |
| tile.zoomDelta = function(_) { | |
| if (!arguments.length) return zoomDelta; | |
| zoomDelta = +_; | |
| return tile; | |
| }; | |
| return tile; | |
| }; |
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <style> | |
| body { | |
| margin: 0; | |
| } | |
| path { | |
| fill: none; | |
| stroke: red; | |
| stroke-linejoin: round; | |
| stroke-width: 1.5px; | |
| } | |
| </style> | |
| <body> | |
| <script src="//d3js.org/d3.v4.0.0-alpha.50.min.js"></script> | |
| <script src="//d3js.org/topojson.v1.min.js"></script> | |
| <script src="d3-geo-tile.js"></script> | |
| <script> | |
| var width = Math.max(960, window.innerWidth), | |
| height = Math.max(500, window.innerHeight); | |
| var tile = d3.geoTile() | |
| .size([width, height]); | |
| var projection = d3.geoMercator() | |
| .scale((1 << 12) / 2 / Math.PI) | |
| .translate([width / 2, height / 2]); | |
| var center = projection([-100, 40]); | |
| var path = d3.geoPath() | |
| .projection(projection); | |
| var zoom = d3.zoom() | |
| .scaleExtent([1 << 11, 1 << 14]) | |
| .on("zoom", zoomed); | |
| var initialTransform = d3.zoomIdentity | |
| .translate(width - center[0], height - center[1]) | |
| .scale(projection.scale() * 2 * Math.PI); | |
| // With the center computed, now adjust the projection such that | |
| // it uses the zoom behavior’s translate and scale. | |
| projection | |
| .scale(1 / 2 / Math.PI) | |
| .translate([0, 0]); | |
| var svg = d3.select("body").append("svg") | |
| .attr("width", width) | |
| .attr("height", height); | |
| var raster = svg.append("g"); | |
| var vector = svg.append("path"); | |
| d3.json("/mbostock/raw/4090846/us.json", function(error, us) { | |
| if (error) throw error; | |
| svg.call(zoom).call(zoom.transform, initialTransform); | |
| vector.attr("d", path(topojson.mesh(us, us.objects.counties))); | |
| }); | |
| function zoomed() { | |
| var transform = d3.event.transform; | |
| var tiles = tile | |
| .scale(transform.k) | |
| .translate([transform.x, transform.y]) | |
| (); | |
| vector | |
| .attr("transform", transform) | |
| .style("stroke-width", 1 / transform.k); | |
| var image = raster | |
| .attr("transform", "scale(" + tiles.scale + ") translate(" + tiles.translate + ")") | |
| .selectAll("image") | |
| .data(tiles, function(d) { return d; }); | |
| image.exit() | |
| .remove(); | |
| image.enter().append("image") | |
| .attr("xlink:href", function(d) { return "http://" + ["a", "b", "c"][d[0] % 3] + ".tile.openstreetmap.org/" + d[2] + "/" + d[0] + "/" + d[1] + ".png"; }) | |
| .attr("width", 1) | |
| .attr("height", 1) | |
| .attr("x", function(d) { return d[0]; }) | |
| .attr("y", function(d) { return d[1]; }); | |
| } | |
| </script> |
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