微信小程序 纯css画仪表盘

刚看到设计稿的时候第一时间想到的就是用canvas来做这个仪表盘，虽然本人的画布用的不是很好但还可以写一写😀。话不多说直接上代码。最后有纯css方法

<!--wxml-->
<canvas canvas-id="circle" class="circle" >

// js
data: {canvasWidth: 285, // 画布宽度canvasHeight: 285, // 画布高度value: 60, // 当前得分
},/** 绘制仪表盘*/showCanvasRing() {var that = this;var ctx = wx.createCanvasContext("circle");ctx.clearRect(0, 0, that.data.canvasWidth, that.data.canvasHeight); // 清除画布var circle_r = that.data.canvasWidth / 2; //画布的一半，用来找中心点和半径var scoreText = that.data.value>=100?100:that.data.value; // 当前得分 最多100分var descript = '良好'; // 当前描述var date = formatTime(new Date(),'MM-DD'); // 当前日期// 圆弧起点var startAngle = 0.8 * Math.PI;var endAngle = 2.2 * Math.PI;//定义起始点ctx.translate(that.data.canvasWidth / 2, that.data.canvasHeight / 2);// 画圆背景ctx.beginPath();ctx.setStrokeStyle("#6bb7b9");ctx.fillStyle="#6bb7b9";ctx.setLineCap("round");ctx.arc(0, 0, circle_r,2*Math.PI);ctx.fill()ctx.stroke();ctx.closePath();//  白半边圆弧ctx.beginPath();ctx.setStrokeStyle("#FFFFFF");ctx.setLineWidth(10);ctx.setLineCap("round");ctx.arc(0, 0, circle_r - 20, startAngle, endAngle, false);ctx.stroke();ctx.closePath();// 刻度for (let i = 0; i <= 10; i++) {let angle = startAngle + (endAngle - startAngle - 0.1) * (i * 10) / 100;if (angle > Math.PI * 2) {angle = angle - Math.PI * 2}const point = that.getPoint(0, 0, circle_r - 44, angle);const PI_3_2 = Math.PI * 1.5;const PI_1_2 = Math.PI * 0.5;ctx.save()ctx.setFillStyle("#fff");ctx.setFontSize(13);ctx.translate(point.x, point.y)const rotateDegrees = angle >= PI_3_2 ? (angle - PI_3_2) : (angle + PI_1_2);ctx.rotate(rotateDegrees)ctx.fillText(i * 10, 0, 0)ctx.restore()}// 当前得分内圆弧ctx.beginPath();ctx.setStrokeStyle("#FFA64D");ctx.setLineWidth(10);ctx.setLineCap("round");ctx.arc(0, 0, circle_r - 20, startAngle, startAngle + (endAngle - startAngle) * scoreText / 100, false);ctx.stroke();ctx.closePath();// 分数ctx.setTextAlign("center"); // 字体位置ctx.setFillStyle("#fff");ctx.font = "900 50px Arial"ctx.fillText(scoreText, 0, -20);// 描述ctx.setTextAlign("center"); // 字体位置ctx.font = "400 15px Arial"ctx.fillText(descript, 0, 15);// 日期ctx.setTextAlign("center");ctx.setLineWidth(8);ctx.setFontSize(14);ctx.fillText(date + ' 更新', 0, 35);// 绘图ctx.draw();},getPoint: function (x, y, r, angle) {const x1 = x + r * Math.cos(angle);const y1 = y + r * Math.sin(angle);return {x: x1,y: y1}},

到此仪表盘就画完了，最后需求有变动需要再仪表盘上加文本，众所周知canvas在小程序中的层级很高。但是官方说可以使用cover-view | cover-image

 <canvas canvas-id="circle" class="circle" ><cover-view class="lowScore" wx-if="{{showView}}">目前信用分过低</cover-view></canvas>

经过验证cover-view可以做到在canvas上悬浮，但是不能满足所有需求；
比如要悬浮scroll-view ，总不能把内容全部用画布来写吧 ~ ~。也有人说可以将绘画完成后的canvas转成图片进行显示wx.canvasToTempFilePath。我同样也试过但是会报错：canvasToTempFilePath:fail fail canvas is empty，怎么解决试了好半天，由于项目着急也没用太多时间研究了。所有最后我决定使用最原始的方法来实现。来看代码吧 ↓ ↓

 <!--wxml-->
<view class="dashboard"><view class="dashboard-arc"><view class="dashboard-scale"><view wx:for="{{[0,10,20,30,40,50,60,70,80,90,100]}}" wx:key="item">{{item}}</view></view><view class="dashboard-arc-active" style="background: conic-gradient(#FFA64D 0, #FFA64D {{(value*0.75)}}%, transparent 0, transparent);"><view class="dashboard-arc-active-end" style="transform: translateX(-50%) rotate({{(value/100)*270}}deg);"></view></view></view><view class="dashboard-content"><view class="dashboard-content-title">{{value}}</view><view class="dashboard-content-text">{{state}}</view><view class="dashboard-content-desc">{{tool.formatTime(date,'MM-DD')}} 更新</view></view><view class="lowScore" wx-if="{{showView}}">目前信用分过低</view>
...要悬浮的内容
</view>

	/* 仪表盘 */.dashboard {width: 750rpx;height: 600rpx;background: rgba(70, 165, 168, 1);box-shadow: 0px 10px 20px rgba(0, 0, 0, 0.1);text-align: center;position: relative;}.dashboard::before{content: '';width: 570rpx;height: 570rpx;position: absolute;top: 50%;left: 50%;transform: translate(-50%, -50%);background-color: #6bb7b9;border-radius: 50%;}.dashboard-arc{width: 520rpx;height: 520rpx;position: absolute;top: 50%;left: 50%;transform: translate(-50%, -50%);transform: translate(-50%, -50%) rotate(-135deg);border-radius: 50%;background: conic-gradient(#fff 0, #fff 75%, transparent 0, transparent);}.dashboard-arc::before,.dashboard-arc::after{content: "";position: absolute;width: 20rpx;height: 20rpx;border-radius: 50%;background: #fff;}.dashboard-arc::before{left: 50%;top: 0;background-color: #FFA64D;transform: translateX(-50%);}.dashboard-arc::after{left: 0;top: 50%;transform: translateY(-50%);}.dashboard-arc-active{position: absolute;width: 100%;height: 100%;border-radius: 50%;top: 0;left: 0;}.dashboard-arc-active-end{position: absolute;width: 20rpx;height:100%;top: 0;left: 50%;z-index: 1;}.dashboard-arc-active-end::before{content: '';width: 20rpx;height: 20rpx;position: absolute;top: 0;left: 0;background: #FFA64D;border-radius: 50%;}.dashboard-scale{background-color: #6bb7b9;width: 480rpx;height: 480rpx;border-radius: 50%;position: relative;top: 50%;left: 50%;z-index: 99;font-size: 20rpx;transform: translate(-50%, -50%);color: #fff;}.dashboard-scale>view{position: absolute;top: 50%;height:calc(100% - 10rpx);left: 50%;transform: translate(-50%,-50%);}.dashboard-scale>view:nth-child(2){transform:translate(-50%,-50%)rotate(27deg);}.dashboard-scale>view:nth-child(3){transform:translate(-50%,-50%)rotate(54deg);}.dashboard-scale>view:nth-child(4){transform:translate(-50%,-50%)rotate(81deg);}.dashboard-scale>view:nth-child(5){transform:translate(-50%,-50%)rotate(108deg);}.dashboard-scale>view:nth-child(6){transform:translate(-50%,-50%)rotate(135deg);}.dashboard-scale>view:nth-child(7){transform:translate(-50%,-50%)rotate(162deg);}.dashboard-scale>view:nth-child(8){transform:translate(-50%,-50%)rotate(189deg);}.dashboard-scale>view:nth-child(9){transform:translate(-50%,-50%)rotate(216deg);}.dashboard-scale>view:nth-child(10){transform:translate(-50%,-50%)rotate(243deg);}.dashboard-scale>view:nth-child(11){transform:translate(-50%,-50%)rotate(270deg);}.dashboard-content{position: absolute;width: 300rpx;height: 300rpx;top: 50%;left: 50%;transform: translate(-50%, -50%);color: #fff;border-radius: 50%;padding: 20rpx;}.dashboard-content-title{font-size: 115rpx;font-weight: 900;}.dashboard-content-text{font-size: 25rpx;}.dashboard-content-desc{font-size: 20rpx;}

以上就是所有代码了，觉得对你有用的话就点个赞吧 ！
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