JavaScript生成图形验证码

getGVerify:function (id)
 {
 
  function GVerify(options) { //创建一个图形验证码对象，接收options对象为参数
   this.options = { //默认options参数值
    id: "", //容器Id
    canvasId: "verifyCanvas", //canvas的ID
    width: "100", //默认canvas宽度
    height: "30", //默认canvas高度
    type: "blend", //图形验证码默认类型blend:数字字母混合类型、number:纯数字、letter:纯字母
    code: ""
   }
 
   if(Object.prototype.toString.call(options) == "[object Object]"){//判断传入参数类型
    for(var i in options) { //根据传入的参数，修改默认参数值
     this.options[i] = options[i];
    }
   }else{
    this.options.id = options;
   }
 
   this.options.numArr = "0,1,2,3,4,5,6,7,8,9".split(",");
   this.options.letterArr = getAllLetter();
 
   this._init();
   this.refresh();
  }
 
  GVerify.prototype = {
   /**版本号**/
   version: '1.0.0',
 
   /**初始化方法**/
   _init: function() {
    var con = document.getElementById(this.options.id);
    var canvas = document.createElement("canvas");
    /*this.options.width = con.offsetWidth > 0 ? con.offsetWidth : "100";
    this.options.height = con.offsetHeight > 0 ? con.offsetHeight : "30";*/
    canvas.id = this.options.canvasId;
    canvas.width = this.options.width;
    canvas.height = this.options.height;
    canvas.style.cursor = "pointer";
    canvas.innerHTML = "您的浏览器版本不支持canvas";
    con.appendChild(canvas);
    var parent = this;
    canvas.onclick = function(){
     parent.refresh();
    }
   },
 
   /**生成验证码**/
   refresh: function() {
    this.options.code = '';
    var canvas = document.getElementById(this.options.canvasId);
    if(canvas.getContext) {
     var ctx = canvas.getContext('2d');
    }
    ctx.textBaseline = "middle";
 
    ctx.fillStyle = randomColor(180, 240);
    ctx.fillRect(0, 0, this.options.width, this.options.height);
 
    if(this.options.type == "blend") { //判断验证码类型
     var txtArr = this.options.numArr.concat(this.options.letterArr);
    } else if(this.options.type == "number") {
     var txtArr = this.options.numArr;
    } else {
     var txtArr = this.options.letterArr;
    }
 
    for(var i = 1; i <= 4; i++) {
     var txt = txtArr[randomNum(0, txtArr.length)];
     this.options.code += txt;
     ctx.font = '20px SimHei';
     //ctx.font = randomNum(this.options.height/2, this.options.height) + 'px SimHei'; //随机生成字体大小
     ctx.fillStyle = randomColor(50, 160); //随机生成字体颜色
     /* ctx.shadowOffsetX = randomNum(-3, 3);
     ctx.shadowOffsetY = randomNum(-3, 3);*/
     ctx.shadowBlur = randomNum(-3, 3);
     ctx.shadowColor = "rgba(0, 0, 0, 0.3)";
     var x = this.options.width / 5 * i;
     var y = this.options.height / 2;
     var deg = randomNum(-30, 30);
     /**设置旋转角度和坐标原点**/
     ctx.translate(x, y);
     ctx.rotate(deg * Math.PI / 180);
     ctx.fillText(txt, 0, 0);
     /**恢复旋转角度和坐标原点**/
     ctx.rotate(-deg * Math.PI / 180);
     ctx.translate(-x, -y);
    }
    /**绘制干扰线**/
    for(var i = 0; i < 4; i++) {
     ctx.strokeStyle = randomColor(40, 180);
     ctx.beginPath();
     ctx.moveTo(randomNum(0, this.options.width/2), randomNum(0, this.options.height/2));
     ctx.lineTo(randomNum(0, this.options.width/2), randomNum(0, this.options.height));
     ctx.stroke();
    }
    /**绘制干扰点**/
    for(var i = 0; i < this.options.width/4; i++) {
     ctx.fillStyle = randomColor(0, 255);
     ctx.beginPath();
     ctx.arc(randomNum(0, this.options.width), randomNum(0, this.options.height), 1, 0, 2 * Math.PI);
     ctx.fill();
    }
   },
 
   /**验证验证码**/
   validate: function(code){
    var verifyCode = code.toLowerCase();
    var v_code = this.options.code.toLowerCase();
    if(verifyCode == v_code){
     return true;
    }else{
     return false;
    }
   }
  }
 
  /**生成字母数组**/
  function getAllLetter() {
   var letterStr = "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";
   return letterStr.split(",");
  }
  /**生成一个随机数**/
  function randomNum(min, max) {
   return Math.floor(Math.random() * (max - min) + min);
  }
  /**生成一个随机色**/
  function randomColor(min, max) {
   var r = randomNum(min, max);
   var g = randomNum(min, max);
   var b = randomNum(min, max);
   return "rgb(" + r + "," + g + "," + b + ")";
  }
 
  return new GVerify(id);
 }

var verifyCode = new GVerify(id);

if(verifyCode.validate(inputCode)){
  return true;
}esle{
  return false;
}