利用canvas写一个验证码小功能

刚刚开始接触canvas,写个验证码小功能练练手,实现效果图如下:

主要代码如下:

html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <link rel="stylesheet" href="index.css">
</head>
<body>
    <div class="wrapper">
        <div class="inputBox">
            <input type="text" class = 'inputCaptcha' placeholder = "请输入验证码">
            <span class="captchaIcon"></span>
        </div>
        <p class="errorText"></p>
        <div class="canvasBox">
            <div class="imageBox">
                <canvas width =300 height=80 id = 'canvasCaptcha'></canvas>
                <input type="button" class='refresh'>
            </div>
        </div>
        <button class="captchaSubmit">submit</button>
    </div>
    <script src='./jquery.js'></script>
    <script src = './index.js'></script>
</body>
</html>

css

* {
    margin: 0;
    padding: 0;
}

.wrapper {
    width: 345px;
    border: 1px solid #ccc;
    border-radius: 10px;
    padding: 20px 10px;
    margin: 30px 30px;
}

.inputBox {
    width: 345px;
    margin: 0 auto 10px;
    position: relative;
}

.inputBox .inputCaptcha {
    display: inline-block;
    height: 50px;
    width: 86%;
    text-indent: 1em;
    border: 1px solid #ddd;
    border-radius: 5px;
}

.inputBox .captchaIcon {
    display: none;
    position: absolute;
    top: 50%;
    right: 0px;
    margin-top: -16px;
    width: 32px;
    height: 32px;
    background-size: 100% 100%;
}

.errorText {
    width: 345px;
    margin: 0 auto;
    font-size: 12px;
    color: red;
    display: none;
}

.canvasBox {
    width: 345px;
    margin: 10px auto;
    position: relative;
}

#canvasCaptcha {
    border-radius: 10px;
}

.canvasBox .refresh {
    width: 34px;
    height: 34px;
    position: absolute;
    right: 0px;
    top: 50%;
    margin-top: -17px;
    border: 0;
    border-radius: 6px;
    background-image: url('./images/update.png');
    background-size: cover;
}

.captchaSubmit {
    padding: 10px 20px;
    background-color: #62b900;
    border: 0;
    font-size: 20px;
    border-radius: 5px;
    color: #fff;
}

var arr = [0,1,2,3,4,5,6,7,8,9];
for(var i = 65;i < 122;i++){
    if(i>90&&i<97){
        continue;
    }
    arr.push(String.fromCharCode(i));
}
//每个验证码可能出现的字母或数字(区分大小写)
var len = arr.length;
//验证码的长度
var canvasStr,value;
//验证码值
function createCanvas(){
    canvasStr = '';
    value = '';
    for(var i =0 ;i < 6;i++){
        var a = arr[Math.floor(Math.random()*len)];
        canvasStr += a+' ';
        value += a; 
    }
//canvas
    var oCanvas = document.getElementById('canvasCaptcha');
    var ctx = oCanvas.getContext('2d');
    var w = oCanvas.width;
    var h = oCanvas.height;
    var oImg = new Image();
    oImg.src = './images/bg.jpg';
    oImg.onload = function(){
        var pattern = ctx.createPattern(oImg,'repeat');
        ctx.fillStyle = pattern;
        ctx.fillRect(0,0,w,h); 
        ctx.fillStyle = '#ccc';
        ctx.textAlign = 'center';
        ctx.font = '46px Roboto Slab';
        ctx.setTransform(1,-0.12,0.2,1,0,12);
        ctx.fillText(canvasStr,w/2,60);
    }
}

createCanvas();

//验证输入的验证码与图中验证码时候相等
function captcha(e){
    if(e == value){
        return true;
    }
    else{
        return false;
    }
}

//点击提交按钮时的结果
function showResult(){
    var inputValue = $('.inputCaptcha').val();
    
    if(inputValue == '' ||inputValue == null || inputValue == 'undefined'){
        $('.errorText').css({display:'inline-block'}).html('验证码不能为空,请重新输入!');
        $('.captchaIcon').css({display:'inline-block',backgroundImage:"url('./images/false.png')"});
    }else{
        var flag = captcha(inputValue);
        if(!flag){
            $('.errorText').css({display:'inline-block'}).html('验证码错误,请重新输入!');
            $('.captchaIcon').css({display:'inline-block',backgroundImage:"url('./images/false.png')"});
        }else{
            $('.captchaIcon').css({display:'inline-block',backgroundImage:"url('./images/true.png')"});
        }
    }
}
$('.captchaSubmit').click(showResult);//提交
$('.refresh').click(createCanvas);//刷新
//点击input框
$('.inputCaptcha').focus(function(){
    $('.errorText').add($('.captchaIcon')).fadeOut(100);
})