如何在uniapp中实现手写板功能

<template>
  <view>
    <canvas class="canvas" @touchstart="startDraw" @touchmove="drawing" @touchend="endDraw"></canvas>
  </view>
</template>

<script>
  export default {
    methods: {
      startDraw(e) {
        // 获取手写板绘制的起始点
      },
      drawing(e) {
        // 进行绘制操作，根据手指移动的轨迹更新笔迹
      },
      endDraw(e) {
        // 绘制结束，保存或上传手写板的内容
      }
    }
  }
</script>

<style>
  .canvas {
    width: 100%;
    height: 100%;
  }
</style>

startDraw(e) {
  const ctx = uni.createCanvasContext('canvas', this);
  ctx.setStrokeStyle('#000000');
  ctx.setLineWidth(2);
  ctx.beginPath();

  this.startX = e.touches[0].x;
  this.startY = e.touches[0].y;
},
drawing(e) {
  const ctx = uni.createCanvasContext('canvas', this);
  ctx.moveTo(this.startX, this.startY);
  ctx.lineTo(e.touches[0].x, e.touches[0].y);
  ctx.stroke();

  this.startX = e.touches[0].x;
  this.startY = e.touches[0].y;
},
endDraw(e) {
  // 绘制结束，保存或上传手写板的内容
},