<template>
  <div class="s-canvas">
    <canvas id="s-canvas"
            :width="contentWidth"
            :height="contentHeight"></canvas>
  </div>
</template>
<script>
export default {
    name: 'SIdentify',
    props: {
        fresh: true,
        fontSizeMin: {
            type: Number,
            default: 20
        },
        fontSizeMax: {
            type: Number,
            default: 36
        },
        backgroundColorMin: {
            type: Number,
            default: 180
        },
        backgroundColorMax: {
            type: Number,
            default: 240
        },
        colorMin: {
            type: Number,
            default: 50
        },
        colorMax: {
            type: Number,
            default: 160
        },
        lineColorMin: {
            type: Number,
            default: 40
        },
        lineColorMax: {
            type: Number,
            default: 180
        },
        dotColorMin: {
            type: Number,
            default: 0
        },
        dotColorMax: {
            type: Number,
            default: 255
        },
        contentWidth: {
            type: Number,
            default: 112
        },
        contentHeight: {
            type: Number,
            default: 38
        }
    },
    data() {
        return {
            identifyCodes: 'abcdefghijkmnpqrstuvwxyzABCEFGHJKLMNPQRSTWXYZ1234567890',
            identifyCode: ''
        };
    },
    methods: {
        // 生成一个随机数
        randomNum(min, max) {
            return Math.floor(Math.random() * (max - min) + min);
        },
        // 生成一个随机的颜色
        randomColor(min, max) {
            let r = this.randomNum(min, max);
            let g = this.randomNum(min, max);
            let b = this.randomNum(min, max);
            return 'rgb(' + r + ',' + g + ',' + b + ')';
        },
        drawPic() {
            let canvas = document.getElementById('s-canvas');
            let ctx = canvas.getContext('2d');
            ctx.textBaseline = 'bottom';
            // 绘制背景
            ctx.fillStyle = this.randomColor(
                this.backgroundColorMin,
                this.backgroundColorMax
            );
            ctx.fillRect(0, 0, this.contentWidth, this.contentHeight);
            // 绘制文字
            for (let i = 0; i < this.identifyCode.length; i++) {
                this.drawText(ctx, this.identifyCode[i], i);
            }
            //    this.drawLine(ctx)
            this.drawDot(ctx);
        },
        drawText(ctx, txt, i) {
            ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax);
            ctx.font =
                this.randomNum(this.fontSizeMin, this.fontSizeMax) + 'px SimHei';
            let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1));
            let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5);
            var deg = this.randomNum(-10, 10);
            // 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);
        },
        drawLine(ctx) {
            //     绘制干扰线
            for (let i = 0; i < 3; i++) {
                ctx.strokeStyle = this.randomColor(
                    this.lineColorMin,
                    this.lineColorMax
                );
                ctx.beginPath();
                ctx.moveTo(
                    this.randomNum(0, this.contentWidth),
                    this.randomNum(0, this.contentHeight)
                );
                ctx.lineTo(
                    this.randomNum(0, this.contentWidth),
                    this.randomNum(0, this.contentHeight)
                );
                ctx.stroke();
            }
        },
        drawDot(ctx) {
            // 绘制干扰点
            for (let i = 0; i < 30; i++) {
                ctx.fillStyle = this.randomColor(0, 255);
                ctx.beginPath();
                ctx.arc(
                    this.randomNum(0, this.contentWidth),
                    this.randomNum(0, this.contentHeight),
                    1,
                    0,
                    2 * Math.PI
                );
                ctx.fill();
            }
        },
        // 生成四位随机验证码
        makeCode(o, l) {
            this.identifyCode = '';
            for (let i = 0; i < l; i++) {
                this.identifyCode += this.identifyCodes[
                    this.randomNum(0, this.identifyCodes.length)
                ];
            }
 
            //绘制图片
            this.drawPic();
 
            //传值给父组件
            this.$emit('makedCode', this.identifyCode);
        }
    },
    watch: {
        fresh() {
            //监听事件
            this.makeCode(this.identifyCodes, 4);
        }
    }
};
</script>
