This is the code for Chapter 11, Figure 4 from D3.js in Action showing how to draw geodata using d3.geo.path().context().
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Ch. 11, Fig. 4 - D3.js in Action
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| <html> | |
| <head> | |
| <title>D3 in Action Chapter 11 - Example 2</title> | |
| <meta charset="utf-8" /> | |
| <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script> | |
| </head> | |
| <style> | |
| body, html { | |
| margin: 0; | |
| } | |
| canvas { | |
| position: absolute; | |
| width: 500px; | |
| height: 500px; | |
| } | |
| svg { | |
| position: absolute; | |
| width:500px; | |
| height:500px; | |
| } | |
| path.country { | |
| fill: gray; | |
| stroke-width: 1; | |
| stroke: black; | |
| opacity: .5; | |
| } | |
| path.sample { | |
| stroke: black; | |
| stroke-width: 1px; | |
| fill: red; | |
| fill-opacity: .5; | |
| } | |
| line.link { | |
| stroke-width: 1px; | |
| stroke: black; | |
| stroke-opacity: .5; | |
| } | |
| circle.node { | |
| fill: red; | |
| stroke: white; | |
| stroke-width: 1px; | |
| } | |
| circle.xy { | |
| fill: pink; | |
| stroke: black; | |
| stroke-width: 1px; | |
| } | |
| </style> | |
| <body> | |
| <canvas height="500" width="500"></canvas> | |
| <div id="viz"> | |
| <svg></svg> | |
| </div> | |
| </body> | |
| <footer> | |
| <script> | |
| sampleData = d3.range(2000).map(function(d) { | |
| var datapoint = {}; | |
| datapoint.id = "Sample Feature " + d; | |
| datapoint.type = "Feature"; | |
| datapoint.properties = {}; | |
| datapoint.geometry = {}; | |
| datapoint.geometry.type = "Polygon"; | |
| datapoint.geometry.coordinates = randomCoords(); | |
| return datapoint; | |
| }) | |
| d3.json("world.geojson", function(data) {createMap(data)}); | |
| function createMap(countries) { | |
| projection = d3.geo.mercator().scale(100).translate([250,250]); | |
| geoPath = d3.geo.path().projection(projection); | |
| mapZoom = d3.behavior.zoom().translate(projection.translate()).scale(projection.scale()).on("zoom", zoomed); | |
| d3.select("svg").call(mapZoom); | |
| zoomed(); | |
| function zoomed() { | |
| projection.translate(mapZoom.translate()).scale(mapZoom.scale()); | |
| var context = d3.select("canvas").node().getContext("2d"); | |
| context.clearRect(0,0,500,500); | |
| context.strokeStyle = "black"; | |
| context.fillStyle = "gray"; | |
| context.lineWidth = "1px"; | |
| for (var x in countries.features) { | |
| context.beginPath(); | |
| geoPath.context(context)(countries.features[x]); | |
| context.stroke() | |
| context.fill(); | |
| } | |
| context.strokeStyle = "black"; | |
| context.fillStyle = "rgba(255,0,0,.2)"; | |
| context.lineWidth = 1; | |
| for (var x in sampleData) { | |
| context.beginPath(); | |
| geoPath.context(context)(sampleData[x]); | |
| context.stroke() | |
| context.fill(); | |
| } | |
| } | |
| } | |
| function randomCoords() { | |
| var randX = (Math.random() * 350) - 175; | |
| var randY = (Math.random() * 170) - 85; | |
| return [[[randX - 5,randY],[randX,randY - 5],[randX - 10,randY - 5],[randX - 5,randY]]]; | |
| } | |
| </script> | |
| </footer> | |
| </html> |
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