微信小程序实现实时圆形进度条的方法示例

前言

最近工作中为了做一个录制按钮，研究了下小程序的实时圆形进度条实现，下面这篇文章就来给大家详细的介绍了实现的方法示例，废话不多说，先来看看效果图吧。

效果图如下

实现思路

建立两个canvas标签，先绘制底层的浅灰色圆圈背景，再绘制上层的红色进度条。

WXML代码

<view class="wrap"> <view class="circle-box"> <canvas class="circle" style="width:200px; height:200px;" canvas-id="canvasArcCir"> </canvas> <canvas class="circle" style="z-index: -5; width:200px; height:200px;" canvas-id="canvasCircle"> </canvas> <view class="draw_btn" bindtap="drawCircle">开始动态绘制</view> </view></view>

WXSS代码

特别注意：底层的canvas最好使用

z-index:-5；放置于底层

page { width: 100%; height: 100%; background-color: #fff;}.circle-box { text-align: center; margin-top: 10vw;}.circle { position: absolute; left: 0; right: 0; margin: auto;}.draw_btn { width: 35vw; position: absolute; top: 33vw; right: 0; left: 0; margin: auto; border: 1px #000 solid; border-radius: 5vw;}

JS代码

//获取应用实例var app = getApp()var interval;var varName;var ctx = wx.createCanvasContext('canvasArcCir');Page({ data: { }, drawCircle: function () { clearInterval(varName); function drawArc(s, e) { ctx.setFillStyle('white'); ctx.clearRect(0, 0, 200, 200); ctx.draw(); var x = 100, y = 100, radius = 96; ctx.setLineWidth(5); ctx.setStrokeStyle('#d81e06'); ctx.setLineCap('round'); ctx.beginPath(); ctx.arc(x, y, radius, s, e, false); ctx.stroke() ctx.draw() } var step = 1, startAngle = 1.5 * Math.PI, endAngle = 0; var animation_interval = 1000, n = 60; var animation = function () { if (step <= n) { endAngle = step * 2 * Math.PI / n + 1.5 * Math.PI; drawArc(startAngle, endAngle); step++; } else { clearInterval(varName); } }; varName = setInterval(animation, animation_interval); }, onReady: function () { //创建并返回绘图上下文context对象。 var cxt_arc = wx.createCanvasContext('canvasCircle'); cxt_arc.setLineWidth(6); cxt_arc.setStrokeStyle('#eaeaea'); cxt_arc.setLineCap('round'); cxt_arc.beginPath(); cxt_arc.arc(100, 100, 96, 0, 2 * Math.PI, false); cxt_arc.stroke(); cxt_arc.draw(); }, onLoad: function (options) { }})

注意的要点

1、关于小程序canvas绘制，请观看微信小程序官方文档绘制