在工作中我们可能会遇到这样的需求,根据后台生成的文字验证码生成图片验证码,这里可以利用canvas完成这一需求,代码如下:
创建getcode.js,内容如下:
/** * 根据已知的验证码生成图片验证码 */ var getGVerify = function(id,value){ function GVerify(options,value) { //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 "70", //默认canvas宽度 height: "36", //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: "", value: value } 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._init(); this.refresh(value); } 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"); 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; }, /**生成验证码**/ refresh: function(value) { 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); var txtArr = value.split(""); for(var i = 1; i <= value.length; i++) { //value.length可控制验证码位数 var txt = txtArr[i-1]; 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 / (value.length+1) * 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(); } } } /**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,value); } export default getGVerify;
使用方法:
引入getcode.js,
import getGVerify from 'url/getCode.js' //url为文件地址
在js中调用:
getGVerify(id,code) //id为输出的dom节点的id,code为后台生成的验证码