This is similar to Map Pan & Zoom IV but with unprojected raw GeoJSON, which is scaled to fit the canvas.
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May 26, 2017 17:57
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Map Pan & Zoom & Fit
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <body> | |
| <script src="//d3js.org/d3.v4.min.js"></script> | |
| <script> | |
| var width = 960, | |
| height = 500 | |
| var zoom = d3.zoom() | |
| .scaleExtent([1, 100]) | |
| .on('zoom', zoomed) | |
| var canvas = d3.select("body").append("canvas") | |
| .attr("width", width) | |
| .attr("height", height) | |
| var context = canvas.node().getContext("2d") | |
| context.lineJoin = "round" | |
| context.lineCap = "round" | |
| context.lineWidth = 0.5 | |
| var mercator = d3.geoMercator() | |
| var transform = d3.geoIdentity() | |
| var path = d3.geoPath() | |
| .projection({stream: function(s) { return mercator.stream(transform.stream(s)) }}) | |
| .context(context) | |
| var render = function () {} | |
| d3.json('ecuador-simplified.geojson', onLoad) | |
| function onLoad (err, geojson) { | |
| if (err) throw err | |
| mercator | |
| .scale(1) | |
| .translate([0, 0]) | |
| var b = path.bounds(geojson), | |
| dx = b[1][0] - b[0][0], | |
| dy = b[1][1] - b[0][1], | |
| x = (b[0][0] + b[1][0]) / 2, | |
| y = (b[0][1] + b[1][1]) / 2, | |
| s = .95 / Math.max(dx / width, dy / height), | |
| t = [width / 2 - s * x, height / 2 - s * y] | |
| mercator | |
| .scale(s) | |
| .translate(t) | |
| render = function() { | |
| context.fillStyle = "#fff", context.fillRect(0, 0, width, height); | |
| context.beginPath(), path(geojson), context.strokeStyle = "#000", context.stroke() | |
| } | |
| canvas.call(zoom) | |
| render() | |
| } | |
| function zoomed () { | |
| var t = d3.event.transform | |
| transform | |
| .translate([t.x, t.y]) | |
| .scale(t.k) | |
| render() | |
| } | |
| </script> | |
| </body> |
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