<template>
    <div class="s-canvas">
        <canvas id="s-canvas" :width="props.contentWidth" :height="props.contentHeight"></canvas>
    </div>
</template>
 
<script setup>
import { onMounted, watch } from 'vue';

const props = defineProps({
    identifyCode: {
        type: String,
        default: '1234'
    },
    fontSizeMin: {
        type: Number,
        default: 35
    },
    fontSizeMax: {
        type: Number,
        default: 35
    },
    backgroundColorMin: {
        type: Number,
        default: 180
    },
    backgroundColorMax: {
        type: Number,
        default: 240
    },
    colorMin: {
        type: Number,
        default: 50
    },
    colorMax: {
        type: Number,
        default: 160
    },
    lineColorMin: {
        type: Number,
        default: 100
    },
    lineColorMax: {
        type: Number,
        default: 200
    },
    dotColorMin: {
        type: Number,
        default: 0
    },
    dotColorMax: {
        type: Number,
        default: 255
    },
    contentWidth: {
        type: Number,
        default: 120
    },
    contentHeight: {
        type: Number,
        default: 40
    }
})

// 生成一个随机数
const randomNum = (min, max) => {
    return Math.floor(Math.random() * (max - min) + min)
}

// 生成一个随机的颜色
const randomColor = (min, max) => {
    let r = randomNum(min, max)
    let g = randomNum(min, max)
    let b = randomNum(min, max)
    return 'rgb(' + r + ',' + g + ',' + b + ')'
}

// 绘制干扰线
const drawLine = (ctx) => {
    for (let i = 0; i < 3; i++) {
        ctx.strokeStyle = randomColor(props.lineColorMin, props.lineColorMax)
        ctx.beginPath()
        ctx.moveTo(randomNum(0, props.contentWidth), randomNum(0, props.contentHeight))
        ctx.lineTo(randomNum(0, props.contentWidth), randomNum(0, props.contentHeight))
        ctx.stroke()
    }
}

const drawText = (ctx, txt, i) => {
    ctx.fillStyle = randomColor(props.colorMin, props.colorMax)
    ctx.font = randomNum(props.fontSizeMin, props.fontSizeMax) + 'px SimHei'
    let x = (i + 1) * (props.contentWidth / (props.identifyCode.length + 1))
    let y = randomNum(props.fontSizeMax, props.contentHeight - 5)
    var deg = randomNum(-10, 10)
    // 修改坐标原点和旋转角度
    ctx.translate(x, y)
    ctx.rotate(deg * Math.PI / 100)
    ctx.fillText(txt, 0, 0)
    // 恢复坐标原点和旋转角度
    ctx.rotate(-deg * Math.PI / 100)
    ctx.translate(-x, -y)
}

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.contentWidth), randomNum(0, props.contentHeight), 1, 0, 2 * Math.PI)
        ctx.fill()
    }
}

const drawPic = () => {
    let canvas = document.getElementById('s-canvas')
    let ctx = canvas.getContext('2d')
    ctx.textBaseline = 'bottom'
    // 绘制背景
    ctx.fillStyle = randomColor(props.backgroundColorMin, props.backgroundColorMax)
    ctx.fillRect(0, 0, props.contentWidth, props.contentHeight)
    // 绘制文字
    for (let i = 0; i < props.identifyCode.length; i++) {
        drawText(ctx, props.identifyCode[i], i)
    }
    drawLine(ctx)
    drawDot(ctx)
}

watch(() => props.identifyCode, (newValue, oldValue) => {
    drawPic()
})

onMounted(() => {
    drawPic()
})
</script>
<style scoped lang='css'>
.s-canvas {
    cursor: pointer;
}
</style>
