纯前端实现图片验证码
前言
之前业务系统中验证码一直是由后端返回base64与一个验证码的字符串来实现的,想了下,前端其实可以直接canvas实现,减轻服务器压力。
实现
子组件,允许自定义图片尺寸(默认尺寸为100 * 40)与验证码刷新时间(默认时间为60秒)。同时暴露绘制验证码方法drawPic(),允许父组件直接调用(需要利用ref实现),点击验证码也可手动刷新。
//VerifyCodeImg.vue
<!--验证码生成-->
<template>
<canvas id="canvasDom" :width="props.canvasWidth" :height="props.canvasHeight" @click="drawPic"></canvas>
</template>
<script setup>
import { onMounted, onBeforeUnmount, computed } from 'vue';
let props = defineProps({
canvasWidth: { // 容器宽度
type: Number,
default: 100
},
canvasHeight: { // 容器高度
type: Number,
default: 40
},
refreshTime: {//验证码刷新间隔时间
type: Number,
default: 60
}
}),
emits = defineEmits(['getVerifyCodeStr']),
verifyCodeTimeId = null,//定时器id
randomStr = '0123456789abcdefghijklmnopqrstuvwxyz',// 所有随机字符串
trueRefreshTime = computed(() => {
return props.refreshTime * 1000;
}),
verifyCodeStr = '';//验证码字符串
onMounted(() => {
initVerifyCodeImg();
});
// 初始化
const initVerifyCodeImg = () => {
drawPic();
verifyCodeTimeId = setInterval(() => {
drawPic();
}, trueRefreshTime.value);
};
// 绘制验证码图片
const drawPic = () => {
randomCode();
let canvas = document.getElementById('canvasDom')
let ctx = canvas.getContext('2d')
ctx.textBaseline = 'bottom'
// 绘制背景
ctx.fillStyle = '#e6ecfd'
ctx.fillRect(0, 0, props.canvasWidth, props.canvasHeight)
// 绘制文字
for (let i = 0; i < verifyCodeStr.length; i++) {
drawText(ctx, verifyCodeStr[i], i)
}
drawLine(ctx)
drawDot(ctx)
};
//4个随机字符
const randomCode = () => {
verifyCodeStr = ''
for (let i = 0; i < 4; i++) {
let txt = randomStr[randomNum(0, randomStr.length)];
verifyCodeStr += txt;
}
emits('getVerifyCodeStr', verifyCodeStr);
};
// 随机数
const randomNum = (min, max) => {
return Math.floor(Math.random() * (max - min) + min)
};
// 随机色
const randomColor = (min, max) => {
let r = randomNum(min, max)
let g = randomNum(min, max)
let b = randomNum(min, max)
return 'rgb(' + r + ',' + g + ',' + b + ')'
};
// 绘制文字
const drawText = (ctx, txt, i) => {
let fontSizeMin = 30,// 字体最小值
fontSizeMax = 40;// 字体最大值
ctx.fillStyle = randomColor(50, 160) // 随机生成字体颜色
ctx.font = randomNum(fontSizeMin, fontSizeMax) + 'px SimHei' // 随机生成字体大小
let x = (i + 1) * (props.canvasWidth / (verifyCodeStr.length + 1))
let y = randomNum(fontSizeMax, props.canvasHeight - 5)
var deg = randomNum(-30, 30)
// 修改坐标原点和旋转角度
ctx.translate(x, y)
ctx.rotate(deg * Math.PI / 180)
ctx.fillText(txt, 0, 0)
// 恢复坐标原点和旋转角度
ctx.rotate(-deg * Math.PI / 180)
ctx.translate(-x, -y)
};
// 绘制干扰线
const drawLine = (ctx) => {
for (let i = 0; i < 4; i++) {
ctx.strokeStyle = randomColor(100, 200)
ctx.beginPath()
ctx.moveTo(randomNum(0, props.canvasWidth), randomNum(0, props.canvasHeight))
ctx.lineTo(randomNum(0, props.canvasWidth), randomNum(0, props.canvasHeight))
ctx.stroke()
}
};
// 绘制干扰点
const drawDot = (ctx) => {
// 绘制干扰点
for (let i = 0; i < 30; i++) {
ctx.fillStyle = randomColor(0, 255)
ctx.beginPath()
ctx.arc(randomNum(0, props.canvasWidth), randomNum(0, props.canvasHeight), 1, 0, 2 * Math.PI)
ctx.fill()
}
};
//暴露绘制图片方法供父组件使用
defineExpose({
drawPic
});
onBeforeUnmount(() => {
clearInterval(verifyCodeTimeId);//页面销毁前,需要清除定时器
});
</script>
<style scoped lang='scss'>
#canvasDom {
cursor: pointer;
}
</style>
父组件使用。
<VerifyCodeImg :refreshTime="1" ref="verifyCodeImgRef" @getVerifyCodeStr="getVerifyCodeStr" />
结语
上面是vue3的实现,你也可以改写为vue2的。
原文链接:https://xiblogs.top/?id=63