HarmonyOS 请问图形验证码的示例吗？

Question

请问图形验证码的示例吗？

Answer 1

请参考以下示例：

1.index.ets

import ImageCode from './ImageCode';

@Entry
@Component
struct Index {
  build() {
    Row() {
      TextInput({placeholder:'请输入验证码'})
        .layoutWeight(1)
      ImageCode()
        .width(100)
        .height(40)
    }
    .height('100%')
    .width('100%')
  }
}

2.CommonUtil.ets

export  class  CommonUtil{
  //随机生成文本内容时使用的值
  sCode: string = "1,2,3,4,5,6,7,8,9,0";
  aCode: string[] = this.sCode.split(",");
  aLength: number = this.aCode.length; //获取到数组的长度

  /**
   * 绘制图形验证码
   * @param context
   * @param canvas_width
   * @param canvas_height
   * @returns
   */
  drawImgCode(context: CanvasRenderingContext2D, canvas_width: number = 100, canvas_height: number = 40): string {
    //用于保存验证码
    let showCode: string = ''
    //清楚当前画布内容，用作刷新画布
    context.clearRect(0, 0, canvas_width, canvas_height)

    for (let i = 0; i < 4; i++) { //这里的for循环可以控制验证码位数
      const j = Math.floor(Math.random() * this.aLength); //获取到随机的索引值
      const deg = Math.random() - 0.5; //产生一个随机弧度
      const txt = this.aCode[j]; //得到随机的一个内容
      showCode += txt.toLowerCase(); //转小写
      const x = 10 + i * 20; //文字在canvas上的x坐标
      const y = canvas_height / 2 + Math.random() * 8; //文字在canvas上的y坐标
      context.font = "20vp sans-serif";
      context.translate(x, y);
      context.rotate(deg);
      context.fillStyle = this.getColor();
      context.fillText(txt, 0, 0);
      context.rotate(-deg);
      context.translate(-x, -y);
    }
    for (let i = 0; i <= 5; i++) { //验证码上显示线条
      context.strokeStyle = this.getColor();
      context.beginPath();
      context.moveTo(Math.random() * canvas_width, Math.random() * canvas_height);
      context.lineTo(Math.random() * canvas_width, Math.random() * canvas_height);
      context.stroke();
    }
    for (let i = 0; i <= 20; i++) { //验证码上的小点
      context.strokeStyle = this.getColor(); //随机生成
      context.beginPath();
      const x = Math.random() * canvas_width;
      const y = Math.random() * canvas_height;
      context.moveTo(x, y);
      context.lineTo(x + 1, y + 1);
      context.stroke();
    }
    return showCode
  }

  /**
   * 获取随机颜色 rgb
   * @returns
   */
  getColor() {
    const r = Math.floor(Math.random() * 256);
    const g = Math.floor(Math.random() * 256);
    const b = Math.floor(Math.random() * 256);
    return "rgb(" + r + "," + g + "," + b + ")";
  }
}

3.ImageCode.ets

import {CommonUtil }  from '../pages/CommonUtil';

@Component
export default struct ImageCode {
  //用来配置CanvasRenderingContext2D对象的参数，包括是否开启抗锯齿，true表明开启抗锯齿。
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  //用来创建CanvasRenderingContext2D对象，通过在canvas中调用CanvasRenderingContext2D对象来绘制。
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)
  //指定canvas要绘制的图形的宽（可使用@Prop装饰器装饰，由调用此组件的父组件传递）
  @State canvas_width: number = 100;
  //指定canvas要绘制的图形的高
  @State canvas_height: number = 40;
  //用于接收图形验证码的文本值
  @State showCode: string = ''

  build() {
    Row() {
      //在canvas中调用CanvasRenderingContext2D对象。
      Canvas(this.context)
        .width(this.canvas_width)
        .height(this.canvas_height)
        .backgroundColor('#CCC')
        .onReady(() => {
          //在这里绘制图形
          this.showCode = new CommonUtil().drawImgCode(this.context,this.canvas_width,this.canvas_height)
          console.log(this.showCode)

        })
        .onClick(() => {
          this.showCode = new CommonUtil().drawImgCode(this.context,this.canvas_width,this.canvas_height)
          console.log(this.showCode)
        })
    }
    .width('100%')
    .height('100%')
  }
}