Use D3 to project points rather than leaflet (or OL)
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February 8, 2016 23:38
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Leaflet + D3 using D3 geo to project
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| <html> | |
| <head></head> | |
| <body> | |
| <style> | |
| @import url(//cdnjs.cloudflare.com/ajax/libs/leaflet/0.7.5/leaflet.css); | |
| #map { | |
| width: 960px; | |
| height: 500px; | |
| } | |
| svg { | |
| position: relative; | |
| } | |
| path { | |
| fill: #000; | |
| fill-opacity: .2; | |
| stroke: #fff; | |
| stroke-width: 1.5px; | |
| } | |
| path:hover { | |
| fill: brown; | |
| fill-opacity: .7; | |
| } | |
| </style> | |
| <script src="//d3js.org/d3.v3.min.js" charset="utf-8"></script> | |
| <script src="https://cdnjs.cloudflare.com/ajax/libs/leaflet/0.7.5/leaflet.js"></script> | |
| <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.0.1/jquery.js"></script> | |
| </body> | |
| </html> | |
| <div id="map"></div> | |
| <script> | |
| var doItD3Style = function(map){ | |
| var projection = d3.geo.mercator(); | |
| map.on("viewreset", redraw); | |
| map.on("dragend", redraw); | |
| // map.on("zoom", redraw); | |
| redraw(); | |
| function redraw(){ | |
| $(g2[0]).empty(); | |
| var b = map.getPixelBounds(), | |
| w = b.max.x - b.min.x, | |
| h = b.max.y - b.min.y, | |
| z = map.getZoom(), | |
| c = map.getCenter(), | |
| $p = $(map.getPanes().mapPane), | |
| os = $p.offset(); | |
| svg2 | |
| .attr({ | |
| width:w, | |
| height:h, | |
| }) | |
| .style({ | |
| left:-os.left + 'px', | |
| top:-os.top + 'px' | |
| }) | |
| projection | |
| .scale((1 << 8 + z) / 2 / Math.PI) | |
| .translate([w/2,h/2]) | |
| .center([c.lng,c.lat]); | |
| for(var i = -200;i <= 180;i += 20){ | |
| for(var j = -85;j <= 85; j += 5){ | |
| var pt = projection([i,j]); | |
| var _g = g2.append('g') | |
| .attr({ | |
| transform:"translate(" + pt[0] + "," + pt[1] + ")", | |
| }); | |
| _g.append('circle') | |
| .attr({ | |
| r:5 | |
| }) | |
| .style({ | |
| fill:"#FF0000" | |
| }) | |
| _g.append('text') | |
| .text(i + ',' + j) | |
| } | |
| } | |
| } | |
| } | |
| var doItLeafletStyle = function(map,collection){ | |
| var transform = d3.geo.transform({point: projectPoint}), | |
| path = d3.geo.path().projection(transform); | |
| var feature = g.selectAll("path") | |
| .data(collection.features) | |
| .enter().append("path"); | |
| map.on("viewreset", reset); | |
| reset(); | |
| // Reposition the SVG to cover the features. | |
| function reset() { | |
| var bounds = path.bounds(collection), | |
| topLeft = bounds[0], | |
| bottomRight = bounds[1]; | |
| svg .attr("width", bottomRight[0] - topLeft[0]) | |
| .attr("height", bottomRight[1] - topLeft[1]) | |
| .style("left", topLeft[0] + "px") | |
| .style("top", topLeft[1] + "px"); | |
| g .attr("transform", "translate(" + -topLeft[0] + "," + -topLeft[1] + ")"); | |
| feature.attr("d", path); | |
| } | |
| // Use Leaflet to implement a D3 geometric transformation. | |
| function projectPoint(x, y) { | |
| var point = map.latLngToLayerPoint(new L.LatLng(y, x)); | |
| this.stream.point(point.x, point.y); | |
| } | |
| } | |
| var lmap = new L.Map("map", {center: [37.8, -96.9], zoom: 4}) | |
| .addLayer(new L.TileLayer("http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png")); | |
| var svg = d3.select(lmap.getPanes().overlayPane).append("svg"), | |
| g = svg.append("g").attr("class", "leaflet-zoom-hide"); | |
| var svg2 = d3.select(lmap.getPanes().overlayPane).append("svg"), | |
| g2 = svg2.append("g").attr("class", "leaflet-zoom-hide"); | |
| d3.json("us_states.json", function(error, collection) { | |
| if (error) throw error; | |
| doItLeafletStyle(lmap,collection); | |
| doItD3Style(lmap) | |
| }); | |
| </script> | |
| <script> |
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