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<!doctype html> |
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<html lang="en"> |
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<head lang=en> |
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<meta charset="utf-8"> |
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<title>Tracing a line with d3.js</title> |
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<style> |
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svg { |
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background: #ddd; |
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font: 10px sans-serif; |
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cursor: crosshair; |
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} |
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.line { |
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cursor: crosshair; |
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fill: none; |
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stroke: #000; |
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stroke-width: 2px; |
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stroke-linejoin: round; |
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} |
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#output { |
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position: relative; |
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top: -2em; |
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left: 0.67em; |
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font: 12px/1.4 monospace; |
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} |
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</style> |
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</head> |
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<body> |
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<div id="sketch"></div> |
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<div id="output"></div> |
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<script src="http://d3js.org/d3.v3.min.js"></script> |
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<script src="simplify.js"></script> |
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<script> |
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// based on http://bl.ocks.org/cloudshapes/5661984 by cloudshapes |
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var margin = {top: 0, right: 0, bottom: 0, left: 0}, |
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width = 960 - margin.left - margin.right, |
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height = 500 - margin.top - margin.bottom; |
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// var npoints = 100; |
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var ptdata = []; |
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var session = []; |
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var path; |
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var drawing = false; |
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var output = d3.select('#output'); |
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var line = d3.svg.line() |
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.interpolate("bundle") // basis, see http://bl.ocks.org/mbostock/4342190 |
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.tension(1) |
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.x(function(d, i) { return d.x; }) |
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.y(function(d, i) { return d.y; }); |
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var svg = d3.select("#sketch").append("svg") |
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.attr("width", width + margin.left + margin.right) |
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.attr("height", height + margin.top + margin.bottom) |
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svg.append("g") |
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.attr("transform", "translate(" + margin.left + "," + margin.top + ")"); |
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svg |
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.on("mousedown", listen) |
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.on("touchstart", listen) |
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.on("touchend", ignore) |
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.on("touchleave", ignore) |
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.on("mouseup", ignore) |
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.on("mouseleave", ignore); |
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// ignore default touch behavior |
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var touchEvents = ['touchstart', 'touchmove', 'touchend']; |
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touchEvents.forEach(function (eventName) { |
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document.body.addEventListener(eventName, function(e){ |
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e.preventDefault(); |
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}); |
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}); |
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function listen () { |
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drawing = true; |
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output.text('event: ' + d3.event.type); |
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ptdata = []; // reset point data |
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path = svg.append("path") // start a new line |
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.data([ptdata]) |
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.attr("class", "line") |
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.attr("d", line); |
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if (d3.event.type === 'mousedown') { |
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svg.on("mousemove", onmove); |
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} else { |
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svg.on("touchmove", onmove); |
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} |
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} |
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function ignore () { |
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var before, after; |
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output.text('event: ' + d3.event.type); |
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svg.on("mousemove", null); |
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svg.on("touchmove", null); |
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// skip out if we're not drawing |
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if (!drawing) return; |
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drawing = false; |
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before = ptdata.length; |
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console.group('Line Simplification'); |
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console.log("Before simplification:", before) |
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// simplify |
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ptdata = simplify(ptdata); |
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after = ptdata.length; |
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console.log("After simplification:", ptdata.length) |
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console.groupEnd(); |
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var percentage = parseInt(100 - (after/before)*100, 10); |
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output.html('Points: ' + before + ' => ' + after + '. <b>' + percentage + '% simplification.</b>'); |
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// add newly created line to the drawing session |
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session.push(ptdata); |
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// redraw the line after simplification |
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tick(); |
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} |
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function onmove (e) { |
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var type = d3.event.type; |
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var point; |
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if (type === 'mousemove') { |
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point = d3.mouse(this); |
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output.text('event: ' + type + ': ' + d3.mouse(this)); |
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} else { |
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// only deal with a single touch input |
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point = d3.touches(this)[0]; |
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output.text('event: ' + type + ': ' + d3.touches(this)[0]); |
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} |
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// push a new data point onto the back |
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ptdata.push({ x: point[0], y: point[1] }); |
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tick(); |
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} |
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function tick() { |
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path.attr("d", function(d) { return line(d); }) // Redraw the path: |
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} |
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</script> |
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</body> |
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</html> |
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