A better performing version of this block
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January 21, 2017 21:46
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Bubbles on Canvas
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="utf-8"> | |
| <title>Bubbles</title> | |
| <style> | |
| canvas { | |
| width: 100%; | |
| height: 100%; | |
| position: absolute; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <div id="chart"></div> | |
| <script src="https://d3js.org/d3.v4.min.js"></script> | |
| <script> | |
| (function() { | |
| var width = window.innerWidth * 2, | |
| height = window.innerHeight * 2; | |
| var x = d3.scaleLinear() | |
| .domain([0, 100]) | |
| .range([0, width]); | |
| var y = d3.scaleLinear() | |
| .domain([0, 100]) | |
| .range([0, height]); | |
| var colors = ["rgba(69, 166, 255, 0.5)", "rgba(255, 49, 57, 0.5)", "rgba(236, 240, 241, 0.5)"]; | |
| var colorScale = d3.scaleQuantize().domain([0,1]).range(colors); | |
| var data = d3.range(40).map(function() { | |
| var dataObject = { | |
| x: Math.random() * 100, | |
| y: Math.random() * 100, | |
| yv: Math.random() * 0.4, | |
| size: (Math.random() * 25) + 5, | |
| color: colorScale(Math.random()) | |
| }; | |
| return dataObject; | |
| }); | |
| var canvas = d3.select("#chart").append("canvas") | |
| .attr("width", width) | |
| .attr("height", height) | |
| .attr("id", "canvas"); | |
| // node returns first dom element in a selection | |
| var context = canvas.node().getContext("2d"); | |
| d3.select(window).on('resize', function(){ | |
| var htmlCanvas = document.getElementById('canvas'); | |
| var context = htmlCanvas.getContext('2d'); | |
| width = window.innerWidth * 2; | |
| htmlCanvas.width = width; | |
| height = window.innerHeight * 2; | |
| htmlCanvas.height = height; | |
| x = d3.scaleLinear() | |
| .domain([0, 100]) | |
| .range([0, width]); | |
| y = d3.scaleLinear() | |
| .domain([0, 100]) | |
| .range([0, height]); | |
| }); | |
| // the timer method calls a function repeatedly | |
| d3.timer(function() { | |
| context.clearRect(0, 0, width, height); | |
| data.forEach(function(d) { | |
| d.y -= d.yv; | |
| // Recycle old circles | |
| if(d.y < (0 - d.size) ) { | |
| d.y = 100 + d.size; | |
| } | |
| context.fillStyle = d.color; | |
| context.beginPath(); | |
| context.arc(x(d.x), y(d.y), d.size, 0, 2 * Math.PI); | |
| context.fill(); | |
| }); | |
| }); | |
| })(); | |
| </script> | |
| </body> | |
| </html> |
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