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January 13, 2019 14:39
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<!DOCTYPE html> | |
<html lang="en"> | |
<head> | |
<meta charset="UTF-8"> | |
<meta name="viewport" content="width=device-width, initial-scale=1.0"> | |
<meta http-equiv="X-UA-Compatible" content="ie=edge"> | |
<title>Document</title> | |
</head> | |
<body> | |
<canvas id='canvas' height="150" width="400" style="border: 1px solid"></canvas> | |
<script> | |
let width = 400; | |
let height = 150; | |
let ctx = document.getElementById('canvas').getContext('2d'); | |
let draw = function () { | |
ctx.clearRect(0, 0, width, height); | |
ctx.beginPath(); | |
ctx.fillStyle = '#000'; | |
ctx.moveTo(10, height - 10); | |
let points = [{ x: 10, y: height - 10 }]; | |
for (var i = 1; i < 20; i++) { | |
let x = 10 + i * 20; | |
let y = height - (20 + Math.floor(Math.random() * 50)); | |
points.push({x, y}); | |
} | |
// move to the first point | |
ctx.moveTo(points[0].x, points[0].y); | |
var xc; | |
for (i = 1; i < points.length - 2; i++) { | |
xc = (points[i].x + points[i + 1].x) / 2; | |
var yc = (points[i].y + points[i + 1].y) / 2; | |
ctx.quadraticCurveTo(points[i].x, points[i].y, xc, yc); | |
} | |
// curve through the last two points | |
ctx.quadraticCurveTo(points[i].x, points[i].y, points[i + 1].x, points[i + 1].y); | |
ctx.lineTo(xc + 30, height - 10); | |
ctx.stroke(); | |
ctx.fill(); | |
setTimeout(function () { | |
ctx.restore(); | |
window.requestAnimationFrame(draw); | |
}, 250); | |
} | |
window.requestAnimationFrame(draw); | |
</script> | |
</body> | |
</html> |
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