使用canvas 在React 中实现登陆验证码

使用canvas 在 React 中实现登陆验证码

import React, { Component } from 'react';
import PropTypes from 'prop-types';

class Identify extends Component {
  constructor(props) {
    super(props);
    this.state = {
      identifyCode: '1234',
      fontSizeMin: {
        type: Number,
        default: 24
      },
      fontSizeMax: {
        type: Number,
        default: 30
      },
      backgroundColorMin: {
        type: Number,
        default: 180
      },
      backgroundColorMax: {
        type: Number,
        default: 240
      },
      colorMin: {
        type: Number,
        default: 50
      },
      colorMax: {
        type: Number,
        default: 170
      },
      lineColorMin: {
        type: Number,
        default: 30
      },
      lineColorMax: {
        type: Number,
        default: 180
      },
      dotColorMin: {
        type: Number,
        default: 0
      },
      dotColorMax: {
        type: Number,
        default: 255
      },
      contentWidth: {
        type: Number,
        default: 160
      },
      contentHeight: {
        type: Number,
        default: 30
      }
    };
  }
  componentDidMount() {
    if (this.props.onRef) {
      this.props.onRef(this);
    }
    this.drawPic();
  }
  watchChild(num) {
    this.setState({
      identifyCode: num
    }, () => { this.drawPic(); });
  }
  // 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) {
    const r = this.randomNum(min, max);
    const g = this.randomNum(min, max);
    const b = this.randomNum(min, max);
    return 'rgb(' + r + ',' + g + ',' + b + ')';
  }
  drawPic() {
    const canvas = document.getElementById('s-canvas');
    const ctx = canvas.getContext('2d');
    ctx.textBaseline = 'bottom';
    // 绘制背景
    ctx.fillStyle = this.randomColor(this.state.backgroundColorMin.default, this.state.backgroundColorMax.default);
    ctx.fillRect(0, 0, this.state.contentWidth.default, this.state.contentHeight.default);
    // 绘制文字
    for (let i = 0; i < this.state.identifyCode.length; i++) {
      this.drawText(ctx, this.state.identifyCode[i], i);
    }
    this.drawLine(ctx);
    this.drawDot(ctx);
  }
  drawText(ctx, txt, i) {
    ctx.fillStyle = this.randomColor(this.state.colorMin.default, this.state.colorMax.default);
    ctx.font = this.randomNum(this.state.fontSizeMin.default, this.state.fontSizeMax.default) + 'px SimHei';
    const x = (i + 1) * (160 / (this.state.identifyCode.length + 1));
    const y = this.randomNum(this.state.fontSizeMax.default, this.state.contentHeight.default - 5);
    let deg = this.randomNum(-45, 45);
    // 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 < 8; i++) {
      ctx.strokeStyle = this.randomColor(this.state.lineColorMin.default, this.state.lineColorMax.default);
      ctx.beginPath();
      ctx.moveTo(this.randomNum(0, this.state.contentWidth.default), this.randomNum(0, this.state.contentHeight.default));
      ctx.lineTo(this.randomNum(0, this.state.contentWidth.default), this.randomNum(0, this.state.contentHeight.default));
      ctx.stroke();
    }
  }
  drawDot(ctx) {
    // 绘制干扰点
    for (let i = 0; i < 100; i++) {
      ctx.fillStyle = this.randomColor(0, 255);
      ctx.beginPath();
      ctx.arc(this.randomNum(0, this.state.contentWidth.default), this.randomNum(0, this.state.contentHeight.default), 1, 0, 2 * Math.PI);
      ctx.fill();
    }
  }
  render() {
    return 

      
    
;
  }
}

Identify.propTypes = {
    onRef: PropTypes.func
};
export default Identify;