| licence: mit |
Creating visualizations like this one but using canvas is possible.
The technique is the same as when using it with SVG with the problem that Canvas hasn't got a method to get the whole length of a path. To do it, I've created a hidden SVG first. This other page has a nice explanation about how the SVG path animation work.
The path is the Trans Mongolian train route taken from here but redrawn, since the original is a multi line.
| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <style> | |
| </style> | |
| <body> | |
| <script src="http://d3js.org/d3.v3.min.js"></script> | |
| <script src="http://d3js.org/topojson.v1.min.js"></script> | |
| <script> | |
| var width = 700, | |
| height = 500; | |
| var canvas = d3.select("body").append("canvas") | |
| .attr("width", width) | |
| .attr("height", height); | |
| var context = canvas.node().getContext("2d"); | |
| var projection = d3.geo.stereographic() | |
| .scale(900) | |
| .translate([width / 2, height / 2]) | |
| .rotate([-90, -60]) | |
| .clipAngle(180 - 1e-4) | |
| .clipExtent([[0, 0], [width, height]]) | |
| .precision(1); | |
| var path = d3.geo.path() | |
| .projection(projection); | |
| //.context(context); | |
| var graticule = d3.geo.graticule(); | |
| d3.json("transsiberian.json", function(error, transsiberian) { | |
| d3.json("world-110m.json", function(error, world) { | |
| var countries = topojson.feature(world, world.objects.countries); | |
| var track = topojson.feature(transsiberian, transsiberian.objects.transsiberian); | |
| var pathEl = d3.select("body").append("svg").append("path").attr("d", path(track)); | |
| var length = pathEl.node().getTotalLength(); | |
| d3.select("svg").remove; | |
| d3.transition() | |
| .duration(5000) | |
| .ease("linear") | |
| .tween("zoom", function() { | |
| return function(t) { | |
| context.clearRect(0, 0, width, height); | |
| context.strokeStyle = '#aaa'; | |
| context.fillStyle = '#ccc'; | |
| context.beginPath(); | |
| path.context(context)(graticule()); | |
| context.lineWidth = 0.2; | |
| context.strokeStyle = 'rgba(30,30,30, 0.5)'; | |
| context.stroke(); | |
| context.beginPath(); | |
| path.context(context)(countries); | |
| context.fill(); | |
| context.beginPath(); | |
| path.context(context)(countries); | |
| context.stroke(); | |
| context.lineWidth = 1; | |
| context.strokeStyle = 'rgba(120,60,60, 1)'; | |
| context.setLineDash([length]); | |
| context.lineDashOffset = length*(1-t); | |
| context.beginPath(); | |
| path.context(context)(track); | |
| context.stroke(); | |
| context.setLineDash([]); | |
| } | |
| }); | |
| }); | |
| }); | |
| d3.select(self.frameElement).style("height", height + "px"); | |
| </script> |
| _ A id N | |
| 0 |
| GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137,298.257223563]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]] |
| GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4326"]] |
