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Canvas Line
A
line chart
rendered to Canvas using
d3-shape
.
<!DOCTYPE html> <meta charset="utf-8"> <canvas width="960" height="500"></canvas> <script src="https://d3js.org/d3.v5.min.js"></script> <script> var canvas = document.querySelector("canvas"), context = canvas.getContext("2d"); var margin = {top: 20, right: 20, bottom: 30, left: 50}, width = canvas.width - margin.left - margin.right, height = canvas.height - margin.top - margin.bottom; var parseTime = d3.timeParse("%d-%b-%y"); var x = d3.scaleTime() .range([0, width]); var y = d3.scaleLinear() .range([height, 0]); var line = d3.line() .x(function(d) { return x(d.date); }) .y(function(d) { return y(d.close); }) .curve(d3.curveStep) .context(context); context.translate(margin.left, margin.top); d3.tsv("data.tsv", function(d) { d.date = parseTime(d.date); d.close = +d.close; return d; }).then(function(data) { x.domain(d3.extent(data, function(d) { return d.date; })); y.domain(d3.extent(data, function(d) { return d.close; })); xAxis(); yAxis(); context.beginPath(); line(data); context.lineWidth = 1.5; context.strokeStyle = "steelblue"; context.stroke(); }); function xAxis() { var tickCount = 10, tickSize = 6, ticks = x.ticks(tickCount), tickFormat = x.tickFormat(); context.beginPath(); ticks.forEach(function(d) { context.moveTo(x(d), height); context.lineTo(x(d), height + tickSize); }); context.strokeStyle = "black"; context.stroke(); context.textAlign = "center"; context.textBaseline = "top"; ticks.forEach(function(d) { context.fillText(tickFormat(d), x(d), height + tickSize); }); } function yAxis() { var tickCount = 10, tickSize = 6, tickPadding = 3, ticks = y.ticks(tickCount), tickFormat = y.tickFormat(tickCount); context.beginPath(); ticks.forEach(function(d) { context.moveTo(0, y(d)); context.lineTo(-6, y(d)); }); context.strokeStyle = "black"; context.stroke(); context.beginPath(); context.moveTo(-tickSize, 0); context.lineTo(0.5, 0); context.lineTo(0.5, height); context.lineTo(-tickSize, height); context.strokeStyle = "black"; context.stroke(); context.textAlign = "right"; context.textBaseline = "middle"; ticks.forEach(function(d) { context.fillText(tickFormat(d), -tickSize - tickPadding, y(d)); }); context.save(); context.rotate(-Math.PI / 2); context.textAlign = "right"; context.textBaseline = "top"; context.font = "bold 10px sans-serif"; context.fillText("Price (US$)", -10, 10); context.restore(); } </script>
https://d3js.org/d3.v5.min.js