html:
<div class="cricle"> <canvas class="canvas" id="c"></canvas> <input type="range" id="r" min="0" max="100" step="1"> </div> js: var canvas = document.getElementById('c'); var ctx = canvas.getContext('2d'); var range = document.getElementById('r'); //range控件信息 var rangeValue = range.value; var nowRange = 40; //用于做一个临时的range //画布 var mW = canvas.width = 252; var mH = canvas.height = 252; var lineWidth = 1;//圆 var r = mH / 2; //圆心 var cR = r - 8 * lineWidth; //圆半径
//Sin 曲线 var sX = 0; var axisLength = mW; //轴长 var waveWidth = 0.034 ; //波浪宽度,数越小越宽 var waveHeight = 2; //波浪高度,数越大越高 var speed = 0.01; //波浪速度,数越大速度越快 var xOffset = 1; //波浪x偏移量
ctx.lineWidth = lineWidth; //画圈函数 var drawCircle = function(){
ctx.beginPath();//开始绘制 ctx.fillStyle="rgba(255,255,255,.84)";//设置填充颜色 ctx.arc(r, r, cR+1, 0, 2 * Math.PI); ctx.fill(); ctx.beginPath(); ctx.arc(r, r, cR, 0, 2 * Math.PI); ctx.clip(); } //画sin 曲线函数 var drawSin = function(xOffset, color, waveHeight){ ctx.save(); var points=[]; //用于存放绘制Sin曲线的点 ctx.beginPath(); //在整个轴长上取点 for(var x = sX; x < sX + axisLength; x += 20 / axisLength){ //此处坐标(x,y)的取点,依靠公式 “振幅高*sin(x*振幅宽 + 振幅偏移量)” var y = Math.sin((-sX - x) * waveWidth + xOffset) * 0.8 + 0.1;
var dY = mH * (1 - nowRange / 100 );
points.push([x, dY + y * waveHeight]); ctx.lineTo(x, dY + y * waveHeight); }
//封闭路径 ctx.lineTo(axisLength, mH); ctx.lineTo(sX, mH); ctx.lineTo(points[0][0],points[0][1]); ctx.fillStyle = color; ctx.fill(); ctx.restore(); }; var render = function(){ ctx.clearRect(0, 0, mW, mH);
rangeValue = range.value;
drawCircle();
if(nowRange <= rangeValue){ var tmp = 1; nowRange += tmp; }
if(nowRange > rangeValue){ var tmp = 1; nowRange -= tmp; }
drawSin(xOffset+Math.PI*0.7, 'rgb(253, 210, 170)', 18); drawSin(xOffset, 'rgba(254,113,32,0.70)', 18); drawText(); drawSignText();
xOffset += speed; requestAnimationFrame(render); } //写百分比文本函数 var drawText = function(){ ctx.save(); var size = 0.3*cR; ctx.font = size + 'px Microsoft Yahei'; ctx.textAlign = 'center'; ctx.fillStyle = "#C24700"; ctx.fillText(~~nowRange, r, r + size / 2);
ctx.restore(); }; // 写百分号 var drawSignText = function() { ctx.save(); var size = 0.15*cR; ctx.font = size + 'px Microsoft Yahei'; ctx.textAlign = 'center'; ctx.fillStyle = "#C24700"; ctx.fillText('%', mW/1.6, r + size / 1); ctx.restore(); }
render(); css: .cricle{ width: 252px; height: 252px; border-radius: 50%; border: 1px solid #FFBE99; background: rgba(243, 202, 184, 0.8); .canvas{ border-radius: 50%; background-image: linear-gradient(40deg, #FFFFFF 0%, rgba(255,255,255, 0) 84%); } }