console
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
//画布属性
var mW = canvas.width = 350;
var mH = canvas.height = 350;
var lineWidth = 1;
//圆属性
var r = mH / 2; //圆心
var cR = r - 32 * lineWidth; //圆半径
//Sin 曲线属性
var sX = 0;
var axisLength = mW; //轴长
var waveWidth = 0.018 ; //波浪宽度,数越小越宽
var waveHeight = 16; //波浪高度,数越大越高
var speed = 0.04; //波浪速度,数越大速度越快
var xOffset = 0; //波浪x偏移量
ctx.lineWidth = lineWidth;
//画圈函数
var IsdrawCircled = false;
var drawCircle = function(){
ctx.beginPath();
ctx.strokeStyle = '#1080d0';
ctx.arc(r, r, cR+1, 0, 2 * Math.PI);
ctx.stroke();
ctx.beginPath();
ctx.arc(r, r, cR, 0, 2 * Math.PI);
ctx.clip();
IsdrawCircled = true;
}
//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;
if(IsdrawCircled == false){
drawCircle();
}
if(nowRange <= rangeValue){
var tmp = 1;
nowRange += tmp;
}
if(nowRange > rangeValue){
var tmp = 1;
nowRange -= tmp;
}
drawSin(xOffset+Math.PI*0.7, 'rgba(28, 134, 209, 0.5)', 18);
drawSin(xOffset, '#1c86d1', 18);
drawText();
xOffset += speed;
requestAnimationFrame(render);
}
//写百分比文本函数
var drawText = function(){
ctx.save();
var size = 0.4*cR;
ctx.font = size + 'px Microsoft Yahei';
ctx.textAlign = 'center';
ctx.fillStyle = "rgba(06, 85, 128, 0.5)";
ctx.fillText(~~nowRange + '%', r, r + size / 2);
ctx.restore();
};
render();
<canvas id="c"></canvas>
<input type="range" id="r" min="0" max="100" step="1">
body{
position: relative;
width:100vw;
height: 100vh;
margin: 0;
}
canvas{
position: absolute;
left: 50%;
top: 50%;
margin-left: -150px;
margin-top: -150px;
border: 1px dashed rgba(0,0,0,0.1)
}