Canvas制作简易验证码
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<title>原生canvas开发验证码</title>
<link rel="stylesheet" href="" />
<style>
*{margin: 0;padding: 0;}
body{
width: 200px;
height: 200px;
margin: 0 auto;
margin-top: 40px;
}
a{
display: block;
text-decoration: none;
text-align: center;
vertical-align: middle;
}
</style>
</head>
<body>
<script>
function randomColor(){
var r = Math.floor(Math.random()*255);
var g = Math.floor(Math.random()*255);
var b = Math.floor(Math.random()*255);
return "rgb("+r+","+g+","+b+")"
// return `rgb(r,g,b)`;
}
window.onload = function(){
// alert("hh");
draw();
document.getElementById("bgimg").onclik = function(){
draw();
}
}
function draw(){
var Canvas = document.getElementById("Canvas");//获取到canvas的对象
var context = Canvas.getContext('2d');//获取到canvas画图环境
var width = Canvas.width = 200;//画布的长度
var height = Canvas.height = 60;//画布的高度
context.strokeRect(0,0,width,height);//绘制画布
var sData = "A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,1,2,3,4,5,6,7,8,9,0";//数据
var pData = sData.split(",");//生成数组
var lData = pData.length;//获取数组的长度
for (var i = 0; i < 4; i++) {
var j = Math.floor(Math.random()*lData);//获取到随机的索引值
var txt = pData[j];//得到随机的值
console.log(txt);
var x = 20+i*20;//内容在画布上的X坐标
var y = 20+Math.random()*10;//内容在画布上的Y坐标
var deg = Math.random()*360*Math.PI/180;
context.font = "blod 56px 宋体";//设置内容的文本样式
context.translate(x,y);//移动并设置坐标原点为x,y
context.rotate(deg);
context.fillStyle = randomColor();
context.fillText(txt,0,0);
context.rotate(-deg);
context.translate(-x,-y);
}
//绘制干扰线
for(var i = 0;i<6;i++){
context.strokeStyle = randomColor();
context.beginPath();
context.moveTo(Math.random()*width,Math.random()*height);
context.lineTo(Math.random()*width,Math.random()*height);
context.stroke();
}
// 绘制干扰点
for(var i = 0;i<20;i++){
context.strokeStyle = randomColor();
context.beginPath();
context.arc(Math.random()*width,Math.random()*height,1,0,2*Math.PI);//canvas的内置属性arc画圆（X坐标，Y坐标，半径，起始角，结束角）
context.stroke();
}
}
</script>
<canvas id="Canvas"></canvas>
<a href="" id="bgimg">点击切换</a>
</body>
</html>
