Js生成图片验证码

上代码

/**
 * 【使用说明】
 * 1、生成验证码
 *    函数：
 *         generateRandomCode( dom对象Id );
 *    例：
 *         generateRandomCode( 'id' );
 *    注意：
 *         调用此方法前必须等待dom元素加载完成 !!!
 *
 * 2、验证方法
 *    入参：
 *         VerificationObj[ dom对象Id ].validate( 用户输入的验证码值 );
 *    例：
 *         VerificationObj[ 'id' ].validate( '1234' );
 *    返回：
 *         相同-true 不同-false
 *
 * 其它
 *    博客：https://www.cnblogs.com/sanrenblog/
 */

var VerificationObj = {}; // 验证码对象集合

!(function(window, document) {
    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_" + options.id, // 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 = "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".split(",");

        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');
            } else {
                return;
            }

            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 = 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), randomNum(0, this.options.height));
                ctx.lineTo(randomNum(0, this.options.width), 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
         * @param code 外部传入验证码
         * @returns {boolean}
         */
        validate: function(code) {
            var code = code.toLowerCase();
            var v_code = this.options.code.toLowerCase();
            if (code == v_code) {
                return true;
            } else {
                return false;
            }
        }
    }

    /** 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 + ")";
    }

    window.GVerify = GVerify;
})(window, document);

/**
 * 生成图片验证码
 * @param id
 */
function generateRandomCode(id) {
    if (id == null || id.length <= 0 || id == undefined || ('' + id == '{}'))
        return false;
    var v = new GVerify({
        id: id,
        type: 'blend'
    });
    // 放入集合，后期根据id名取相关对象
    VerificationObj['' + id] = v;
}

转载自：https://blog.csdn.net/qq_39443053/article/details/97961601/