Converting an SVG animation to a video with the MediaRecorder API and a hidden canvas.
Drawing frames from img elements can introduce an extra delay, so this version generates all the frames upfront and then renders them in a loop with requestAnimationFrame().
See also: Canvas animation to video
| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <body> | |
| <svg width="960" height="500"></svg> | |
| <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/4.2.3/d3.min.js"></script> | |
| <script src="https://d3js.org/topojson.v2.min.js"></script> | |
| <script> | |
| var svg = d3.select("svg"), | |
| canvas = document.createElement("canvas"), | |
| width = canvas.width = +svg.attr("width"), | |
| height = canvas.height = +svg.attr("height"), | |
| context = canvas.getContext("2d"); | |
| var projection = d3.geoOrthographic() | |
| .scale(195) | |
| .translate([width / 2, height / 2]) | |
| .precision(0.1); | |
| var path = d3.geoPath().projection(projection); | |
| d3.json("/world-110m.json", function(err, world) { | |
| var data = [], | |
| stream = canvas.captureStream(), | |
| recorder = new MediaRecorder(stream, { mimeType: "video/webm" }); | |
| recorder.ondataavailable = function(event) { | |
| if (event.data && event.data.size) { | |
| data.push(event.data); | |
| } | |
| }; | |
| recorder.onstop = () => { | |
| var url = URL.createObjectURL(new Blob(data, { type: "video/webm" })); | |
| d3.selectAll("canvas, svg").remove(); | |
| d3.select("body") | |
| .append("video") | |
| .attr("src", url) | |
| .attr("controls", true) | |
| .attr("autoplay", true); | |
| }; | |
| var background = svg.append("rect") | |
| .attr("width", width) | |
| .attr("height", height) | |
| .attr("fill", "#fff"); | |
| svg.append("path") | |
| .datum({ type: "Sphere" }) | |
| .attr("stroke", "#222") | |
| .attr("fill", "none"); | |
| svg.append("path") | |
| .datum(topojson.feature(world, world.objects.land)) | |
| .attr("fill", "#222") | |
| .attr("stroke", "none"); | |
| svg.append("path") | |
| .datum(topojson.mesh(world, world.objects.countries, function(a, b) { | |
| return a !== b; | |
| })) | |
| .attr("fill", "none") | |
| .attr("stroke", "#fff"); | |
| var queue = d3.queue(1); | |
| d3.range(120).forEach(function(frame){ | |
| queue.defer(drawFrame, frame / 120); | |
| }); | |
| queue.awaitAll(function(err, frames){ | |
| recorder.start(); | |
| drawFrame(); | |
| function drawFrame() { | |
| if (frames.length) { | |
| context.drawImage(frames.shift(), 0, 0, width, height); | |
| requestAnimationFrame(drawFrame); | |
| } else { | |
| recorder.stop(); | |
| } | |
| } | |
| }); | |
| function drawFrame(t, cb) { | |
| projection.rotate([360 * t]); | |
| svg.selectAll("path").attr("d", path); | |
| var img = new Image(), | |
| serialized = new XMLSerializer().serializeToString(svg.node()), | |
| url = URL.createObjectURL(new Blob([serialized], {type: "image/svg+xml"})); | |
| img.onload = function(){ | |
| cb(null, img); | |
| }; | |
| img.src = url; | |
| } | |
| }); | |
| </script> |
