# Canvas制作动态进度加载水球

2017-01-13 11:02:29来源:csdn作者:lecepin人点击

sin()函数相关

var ctx = canvas.getContext('2d');//画布属性
var mW = canvas.width = 700;
var mH = canvas.height = 300;
var lineWidth = 1;
//Sin 曲线属性
var sX = 0;
var sY = mH / 2;
var axisLength = mW; //轴长
var waveWidth = 0.011 ; //波浪宽度,数越小越宽
var waveHeight = 70; //波浪高度,数越大越高ctx.lineWidth = lineWidth;
//画sin 曲线函数
var drawSin = function(xOffset){
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);
points.push([x, sY + y * waveHeight]);
ctx.lineTo(x, sY + y * waveHeight);
}//封闭路径
ctx.lineTo(axisLength, mH);
ctx.lineTo(sX, mH);
ctx.lineTo(points[0][0],points[0][1]);
ctx.stroke()ctx.restore();
};
drawSin()

var speed = 0.04; //波浪速度，数越大速度越快
var xOffset = 0; //波浪x偏移量

var y = -Math.sin((sX + x) * waveWidth + xOffset);

var render = function(){
ctx.clearRect(0, 0, mW, mH);drawSin(xOffset);
xOffset += speed; //形成动态效果
requestAnimationFrame(render);
}render()

var dY = mH * (1 - nowRange / 100 );

ctx.beginPath();
ctx.arc(r, r, cR, 0, 2 * Math.PI);
ctx.clip();

var waveWidth = 0.015 ; //波浪宽度,数越小越宽
var waveHeight = 6; //波浪高度,数越大越高
var speed = 0.09; //波浪速度，数越大速度越快

<html lang="en">
<meta charset="UTF-8" />
<title>Document</title>
<style type="text/css">
#c{
margin: 0 auto;
display: block;
}
#r{
display: block;
margin: 0 auto;
}
#r::before{
color: black;
content: attr(min);
}
#r::after{
color: black;
content: attr(max);
}
</style>
<body>
<canvas></canvas>
<input type="range" min="0" max="100" step="1"><script type="text/javascript">
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 = 0; //用于做一个临时的range//画布属性
var mW = canvas.width = 250;
var mH = canvas.height = 250;
var lineWidth = 2;//圆属性
var r = mH / 2; //圆心
var cR = r - 16 * lineWidth; //圆半径//Sin 曲线属性
var sX = 0;
var sY = mH / 2;
var axisLength = mW; //轴长
var waveWidth = 0.015 ; //波浪宽度,数越小越宽
var waveHeight = 6; //波浪高度,数越大越高
var speed = 0.09; //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+5, 0, 2 * Math.PI);
ctx.stroke();
ctx.beginPath();
ctx.arc(r, r, cR, 0, 2 * Math.PI);
ctx.clip();}//画sin 曲线函数
var drawSin = function(xOffset){
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);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 = '#1c86d1';
ctx.fill();ctx.restore();
};//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, 0.8)";
ctx.fillText(~~nowRange + '%', r, r + size / 2);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);
drawText(); xOffset += speed;
requestAnimationFrame(render);
}render();
</script>
</body>
</html>效果

CSDN博客地址：http://blog.csdn.net/lecepin