前言
最近公司美术想要一个半环形的图表， 奈何百度了没看到能用的， 便是决定自己手写一下了， 虽然并非通用配置图表， 但是基本的canvas思想应该是有了， 便是给各位用作参考
实现效果
微信截图_20200226110143.png
完整代码
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
* { padding: 0; margin: 0; }
.canvas { margin: 15px auto; display: block; }
</style>
</head>
<body>
<div id="dom"></div>
</body>
<script>
drawRing({now: 588, total: 630, id: 'dom'});
function drawRing({
now, total, id
}) {
// 校验数据
if(now > total) throw new Error(`当前值now:${now}不可大于总数total:${total}`);
// 创建canvas dom
let canvas = document.createElement('canvas');
let dom = document.getElementById(id);
canvas.style.margin = '15px auto';
canvas.style.display = 'block';
if(!dom) throw new Error(`请检查你的id${id}是否正确，该方法使用document.getElementById获取dom`);
dom.appendChild(canvas);
let color1 = '#A8D279';
let color2 = '#FFD098';
let fontSize = 14;
let percentage = now / total;
let text1 = '已上报' + now + '人';
let text2 = '未上报' + total + '人';
let w_width = window.innerWidth;
// let canvas = document.getElementById('canvas');
canvas.width = w_width * 0.6;
canvas.height = w_width * 0.6;
let ctx = canvas.getContext('2d');
ctx.beginPath();
ctx.strokeStyle = color1;
ctx.lineWidth = 20;
let x = canvas.width / 2;
let y = canvas.width / 2;
let radius = canvas.width / 2 - 20;
let startAngle = 0;
let endAngle1 = Math.PI;
let anticlockWise = true;
// 绘制第一个半圆
ctx.arc(x, y, radius, startAngle, endAngle1, true);
ctx.stroke();
// 绘制第二个半圆
ctx.beginPath();
ctx.strokeStyle = color2;
ctx.lineWidth = 20;
let endAngle2 = (Math.PI / 180) * (180 + (percentage * 180));
ctx.arc(x, y, radius, startAngle, endAngle2, true);
ctx.stroke();
ctx.save();
// 绘制文字
ctx.font = fontSize + 'px Arial';
let text1_width = ctx.measureText(text1).width;
// ctx.textAlign = 'center';
ctx.fillText(text1, (canvas.width - text1_width) / 2 + 14, y - 25);
ctx.save();
ctx.font = fontSize + 'px Arial';
let text2_width = ctx.measureText(text2).width;
// ctx.textAlign = 'center';
ctx.fillText(text2, (canvas.width - text2_width) / 2 + 14, y - 5);
ctx.save();
// 绘制文字旁圆点
ctx.beginPath();
console.log(text1_width)
ctx.arc((canvas.width - text1_width) / 2 - 7, y - 3.5 - 25, 7, 0, Math.PI * 2);
ctx.fillStyle = color1;
ctx.fill();
ctx.save();
ctx.beginPath();
console.log(text2_width)
ctx.arc((canvas.width - text2_width) / 2 - 7, y - 3.5 - 5, 7, 0, Math.PI * 2);
ctx.fillStyle = color2;
ctx.fill();
}
</script>
</html>
