canvas验证码 uni-app/小程序

<template>
    <view class="logo-wrapper">
        <view class="logo-img">
            <image src="../../static/images/logo-login.png" mode="widthFix" />
        </view>
        <view class="form-box">
            <view class="form-item">
                <view class="icon-box">
                    <i class="iconfont icon-yonghu"></i>
                </view>
                <input class="ipt" v-model="username" type="text" placeholder="用户名" />
            </view>
            <view class="form-item">
                <view class="icon-box">
                    <i class="iconfont icon-mima"></i>
                </view>
                <input class="ipt" v-model="password" type="password" placeholder="密码" />
            </view>
            <view class="form-item">
                <view class="icon-box">
                    <i class="iconfont icon-yanzhengma"></i>
                </view>
                <input class="ipt short" v-model="capCode" type="text" placeholder="验证码" />
                <canvas class="canvas" canvas-id="yzmCanvas" id="yzmCanvas" @tap="tapCaptcha"></canvas>
            </view>
            <button class="btn-login" @tap="login">登录</button>
        </view>
        <view class="bottom-img">
            <image src="../../static/images/login-bottom.png" mode="widthFix" />
        </view>
    </view>
</template>

<script>
    export default {
        data() {
            return {
                capShow: true,
                username: '',
                password: '',
                capCode: '',
                uuid: ''
            }
        },
        methods: {
            async queryCaptcha() {
                const { data } = await this.$http({
                    url: '/captchaImage',
                    method: 'GET',
                });
                this.uuid = data.data.uuid;
                this.creatCanvas(data.data.image);
            },
            tapCaptcha() {
                this.capShow = false;
                this.$nextTick(() => {
                    this.capShow = true;
                    this.queryCaptcha();
                });
            },
            //得到随机的颜色值
            randomColor() {
                var r = Math.floor(Math.random() * 256);
                var g = Math.floor(Math.random() * 256);
                var b = Math.floor(Math.random() * 256);    
                return 'rgb(' + r + ',' + g + ',' + b + ')';
            },
            creatCanvas(str) {
                const ctx = uni.createCanvasContext('yzmCanvas');
                ctx.setFontSize(28 + Math.floor(Math.random() * 4 - 2));
                ctx.setFillStyle(this.randomColor());
                for (let i = 0; i < 4; i++) {
                    ctx.setFontSize(28 + Math.floor(Math.random() * 4 - 2));
                    ctx.fillText(str[i], 20 * i + 10, 32);
                    ctx.setFillStyle(this.randomColor());
                    // 旋转随机在-3到3之间
                    ctx.rotate((Math.floor(Math.random() * 6 - 3) * Math.PI) / 180);
                }
                // 直线 begin path
                for (let i = 0; i < 4; i++) {
                    ctx.beginPath();
                    ctx.setStrokeStyle(this.randomColor());
                    // x/-10~110 y/-10~50
                    ctx.moveTo(
                      Math.floor(Math.random() * 100) + Math.floor(Math.random() * 20 - 10),
                      Math.floor(Math.random() * 40) + Math.floor(Math.random() * 20 - 10)
                    );
                    ctx.lineTo(
                      Math.floor(Math.random() * 100) + Math.floor(Math.random() * 20 - 10),
                      Math.floor(Math.random() * 40) + Math.floor(Math.random() * 20 - 10)
                    );
                    ctx.stroke();
                 }
                ctx.draw();
            },
            async login() {
                if(this.username === '') {
                    uni.showToast({
                        icon: 'none',
                        title: '请填写用户名'
                    });
                    return;
                }
                if(this.password === '') {
                    uni.showToast({
                        icon: 'none',
                        title: '请填写密码'
                    });
                    return;
                }
                if(this.capCode === '') {
                    uni.showToast({
                        icon: 'none',
                        title: '请填写验证码'
                    });
                    return;
                }
                const { data } = await this.$http({
                    url: '/login',
                    method: 'POST',
                    data: {
                        username: this.username,
                        password: this.password,
                        code: this.capCode,
                        uuid: this.uuid
                    }
                });
                uni.setStorageSync('token', data.data.token);
                
                const res = await this.$http({
                    url: '/personal/userInfo',
                    method: 'GET',
                    data: {
                        token: data.data.token,
                    }
                });
                let userInfo = res.data.data;
                uni.setStorageSync('userInfo', userInfo);
                
                uni.switchTab({
                    url: '/pages/index/index'
                });
            }
        },
        onLoad() {
            this.queryCaptcha();
        },
    }
</script>

<style lang="scss">
.logo-wrapper {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: space-between;
}
.logo-img {
     590upx;
    height: 246upx;
    margin-top: 60upx;
}
.form-box {
     560upx;
    height: 580upx;
    margin: 30upx 0 140upx 0;
}
.form-item {
     100%;
    height: 82upx;
    margin-top: 48upx;
    border-bottom: 1px solid #c1c1c1;
    display: flex;
    align-items: center;
}
.icon-box {
     50upx;
    height: 50upx;
    border-radius: 50%;
    margin-right: 40upx;
    text-align: center;
    line-height: 42upx;
    background-color: #f0443c;
    color: #fff;
    i {
        font-size: 24upx;
    }
}
.ipt {
    flex: 1;
    height: 80upx;
}
.canvas {
     190upx; 
    height: 68upx;
    border: 1px solid #f1f1f1;
    background: #fdfdfd;
}
.btn-login {
    margin-top: 84upx;
    background-color: #f0443c;
    color: #fff;
}
.bottom-img {
     628upx;
    height: 124upx;
    // margin: 50upx auto 0;
}
</style>