最近项目，有一个频谱图和瀑布图的需求，做一下记录，也是网上搜的资料，下面是效果图。因为是静态数据，简单记录，项目后续还需要进一步完善（下面的是瀑布图，另一篇随笔里记录）
<!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>
<style>
#mainCanvas {
border: 1px solid red;
}
</style>
</head>
<body>
<canvas id="mainCanvas" width="1300" height="400"></canvas>
<div id="num"></div>
<script src="https://cdn.bootcss.com/Mock.js/0.1.11/mock-min.js"></script>
<script>
function windowTocanvas(canvas, x, y) {
var bbox = canvas.getBoundingClientRect();
return {
x: x - bbox.left * (canvas.width / bbox.width),
y: y - bbox.top * (canvas.height / bbox.height)
};
}
const numDom = document.getElementById(‘num‘)
// const plan = numDom.createSVGMatrix()
// console.log(‘y‘, plan)
// const plan = numDom.getBoundingClientRect();
// console.log(‘y‘, plan)
const main = document.getElementById(‘mainCanvas‘);
let ctx = main.getContext(‘2d‘);
function draw(data, x, y, color) {
ctx.clearRect(0, 0, 2000, 400);
// 坐标轴
ctx.beginPath();
ctx.moveTo(30, 30);
ctx.lineTo(30, 350);
ctx.strokeStyle = ‘#ccc‘
ctx.closePath();
ctx.stroke();
// ctx.restore()
ctx.save();
ctx.beginPath()
ctx.moveTo(30, 350);
ctx.lineTo(1200, 350);
ctx.strokeStyle = ‘#ccc‘
ctx.closePath();
ctx.stroke();
ctx.restore()
// 单位
ctx.save();
ctx.beginPath()
ctx.font = 12;
ctx.fillStyle = ‘#ccc‘;
ctx.fillText(‘单位‘, 25, 25);
ctx.restore()
// 刻度
// Y
// 计算数据所在y轴
const dataList = data// 计算每个数据处于x轴的坐标，把坐标轴平均到每一度 0/1220 * data + 30
let datax = [];
const numx = 320 / y
dataList.forEach((item, index) => {
datax.push(350 - numx * item)
})
let dataxy = []
const ydate = x;
const step = 1200 / ydate.length
// x轴
for (let i = 30, j = 0; i <= 1200; i += step, j++) {
// console.log(i)
dataxy.push([i, datax[j]]) // 计算数据所在x轴,push到一个新数组，合并xy轴坐标
ctx.save();
ctx.beginPath()
ctx.strokeStyle = "#333"
ctx.closePath();
ctx.stroke();
ctx.restore();
}
// y轴模拟x轴最大值为3000
// 渲染数据DATA
const maxNum = 1220;
const stepX = 320 / 5
for (var i = 350, j = 0; i >= 30; i -= stepX, j += 244) {
ctx.save();
ctx.beginPath()
ctx.moveTo(30, i);
ctx.lineTo(35, i);
ctx.fillText(j, 5, i + 5);
ctx.strokeStyle = "#333"
ctx.closePath();
ctx.stroke();
ctx.restore();
}
// 渲染数据
for (var i = 0; i < dataxy.length; i++) {
if (i === 0) {
ctx.save();
ctx.beginPath()
ctx.moveTo(dataxy[i][0], dataxy[i][1]);
ctx.lineTo(dataxy[i][0], dataxy[i][1]);
ctx.strokeStyle = "red"
// ctx.closePath();
ctx.stroke();
ctx.restore();
}
else {
ctx.save();
ctx.beginPath()
ctx.moveTo(dataxy[i - 1][0], dataxy[i - 1][1]);
ctx.lineTo(dataxy[i][0], dataxy[i][1]);
ctx.strokeStyle = color ? color : "#FF6347"
ctx.stroke();
ctx.restore();
}
}
}
function floor() {
let list = []
let x = []
for (var i = 0; i < 2000; i++) {
list.push(Mock.mock({
"number|1-1200": 100
}).number)
x.push(Mock.mock(‘@now("H:m:s")‘))
}
return { list, x }
}
let listData = floor()
let dataList = listData.list;
let yAxis = 1200;
let xAxis = listData.x;
draw(dataList, xAxis, yAxis);
// let colorList = [‘#FF6347‘, ‘#FFFF33‘, ‘#FF6347‘, ‘#FF00FF‘, ‘#DDA0DD‘, ‘#C0FF3E‘, ‘#87CEFF‘, ‘#FF4500‘, ‘#FF82AB‘, ‘#FF1493‘]
setInterval(function () {
let start = new Date()
listData = floor()
dataList = listData.list;
xAxis = listData.x;
// linecolor = colorList[Math.ceil(Math.random()*10)]
draw(dataList, xAxis, yAxis)
let end = new Date()
numDom.innerHTML = ‘时间‘ + (end - start)
}, 50)
</script>
</body>
</html>