html代码添加
<canvas id="canvas" width="100" height="40" alt="单击刷新"></canvas>
js添加,配置canvas样式,过滤掉较浅的颜色。r * 0.299 + g * 0.578 + b * 0.114>=192就是浅色。
$(function () { draw(show_num); $("#canvas").on('click',function (){draw(show_num)}); }); function draw(show_num) { var canvas_width = $('#canvas').width(); var canvas_height = $('#canvas').height(); var canvas = document.getElementById("canvas");//获取到canvas的对象,演员 var context = canvas.getContext("2d");//获取到canvas画图的环境,演员表演的舞台 canvas.width = canvas_width; canvas.height = canvas_height; var sCode = "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"; var aCode = sCode.split(","); var aLength = aCode.length;//获取到数组的长度 for (var i = 0; i <= 3; i++) { var j = Math.floor(Math.random() * aLength);//获取到随机的索引值 var deg = Math.random() * 30 * Math.PI / 180;//产生0~30之间的随机弧度 var txt = aCode[j];//得到随机的一个内容 show_num[i] = txt.toLowerCase(); var x = 10 + i * 20;//文字在canvas上的x坐标 var y = 20 + Math.random() * 8;//文字在canvas上的y坐标 context.font = "bold 24px 微软雅黑"; context.translate(x, y); context.rotate(deg); context.fillStyle = randomColor(); context.fillText(txt, 0, 0); context.rotate(-deg); context.translate(-x, -y); } for (var i = 0; i <= 5; i++) { //验证码上显示线条 context.strokeStyle = randomColor(); context.beginPath(); context.moveTo(Math.random() * canvas_width, Math.random() * canvas_height); context.lineTo(Math.random() * canvas_width, Math.random() * canvas_height); context.stroke(); } for (var i = 0; i <= 30; i++) { //验证码上显示小点 context.strokeStyle = randomColor(); context.beginPath(); var x = Math.random() * canvas_width; var y = Math.random() * canvas_height; context.moveTo(x, y); context.lineTo(x + 1, y + 1); context.stroke(); } } function randomColor() {//得到随机的颜色值 var sumrgb = 193, r = 0, g = 0, b = 0; while (sumrgb > 192) { //排除浅色 r = Math.floor(Math.random() * 256); g = Math.floor(Math.random() * 256); b = Math.floor(Math.random() * 256); sumrgb = r * 0.299 + g * 0.578 + b * 0.114; } return "rgb(" + r + "," + g + "," + b + ")"; } </script> <style> #canvas { display: inline-block; border: 1px solid #ccc; border-radius: 5px; cursor: pointer; } </style>