插件市场大佬封装好的 组件 可以直接拿过去

<template>
  <view
    class="whole canvas-autograph flexc"
    @touchmove.prevent.stop
    @wheel.prevent.stop
    v-show="modelValue"
  >
    <canvas
      class="scroll-view"
      id="mycanvas"
      canvas-id="mycanvas"
      @touchstart="touchstart"
      @touchmove="touchmove"
      @touchend="touchend"
    />
    <view class="fun-box">
      <view
        class="fun-box-btn clear flex"
        @click="clear"
      >
        <text>清空</text>
      </view>
      <view
        class="fun-box-btn confirm flex"
        @click="confirm"
      >
        <text>确认</text>
      </view>
      <view
        class="fun-box-btn cancel flex"
        @click="cancel"
      >
        <text>取消</text>
      </view>
    </view>
  </view>
</template>

<script setup>
/*
		使用如下
		<canvas-autograph v-model="isCanvas" @complete="complete"/>
		
		// 打开、关闭
		let isCanvas = ref(false)
		// 确认事件
		const complete = e=>{
			console.log(e)
		}
	
	*/
import { ref, reactive, watch, getCurrentInstance } from 'vue'
const hasSignature = ref(false) // 新增：记录是否签名
const emits = defineEmits(['update:modelValue', 'complete'])

const props = defineProps({
  modelValue: Boolean
})
const _this = getCurrentInstance()
watch(
  () => props.modelValue,
  (e) => {
    // 这里可进行 tabbar 的 显示、隐藏  不要也可以
    // 自己写
  },
  {
    immediate: true // 是否默认执行一次  默认为false
  }
)

let points = reactive([]) //路径点集合

let canvaCtx = reactive(uni.createCanvasContext('mycanvas', _this)) //创建绘图对象
//设置画笔样式
canvaCtx.lineWidth = 4
canvaCtx.lineCap = 'round'
canvaCtx.lineJoin = 'round'

//触摸开始，获取到起点
const touchstart = (e) => {
  hasSignature.value = true // 有触摸操作则认为有签名
  let startX = e.changedTouches[0].x
  let startY = e.changedTouches[0].y
  let startPoint = { X: startX, Y: startY }
  points.push(startPoint)
  //每次触摸开始，开启新的路径
  canvaCtx.beginPath()
}
//触摸移动，获取到路径点
const touchmove = (e) => {
  let moveX = e.changedTouches[0].x
  let moveY = e.changedTouches[0].y
  let movePoint = { X: moveX, Y: moveY }
  points.push(movePoint) //存点
  let len = points.length
  if (len >= 2) {
    draw()
  }
}
//绘制路径
const draw = () => {
  let point1 = points[0]
  let point2 = points[1]
  points.shift()
  canvaCtx.moveTo(point1.X, point1.Y)
  canvaCtx.lineTo(point2.X, point2.Y)
  canvaCtx.stroke()
  canvaCtx.draw(true)
}
// 触摸结束，将未绘制的点清空防止对后续路径产生干扰
const touchend = (e) => {
  points = []
}
// 清空画布
const clear = () => {
  hasSignature.value = false // 清空时重置签名标志
  return uni
    .getSystemInfo()
    .then((res) => {
      canvaCtx.clearRect(0, 0, res.windowWidth, res.windowHeight)
      canvaCtx.draw(true)
      return res
    })
    .catch((err) => {
      // console.log(err);
    })
}
// 确认
const confirm = () => {
  if (!hasSignature.value) {
    // 如果没有签名，提示用户
    uni.showToast({
      title: '请先签名',
      icon: 'none',
      duration: 2000
    })
    return
  }

  uni.canvasToTempFilePath({ canvasId: 'mycanvas' }, _this, _this.parent).then((res) => {
    console.log(res.tempFilePath)
    emits('complete', res.tempFilePath)
    cancel()
  })
}
// 取消
const cancel = () => {
  clear().then((res) => emits('update:modelValue', false))
}
</script>

<style scoped lang="scss">
.canvas-autograph {
  position: fixed;
  z-index: 99999;
  width: 100vw;
  height: 100vh;
  top: 0;
  left: 0;
  .scroll-view {
    width: 100%;
    height: 100%;
    background-color: #ffffff;
  }
  .fun-box {
    position: absolute;
    right: 0;
    bottom: 10vh;
    height: auto;
    display: flex;
    flex-direction: column;
    .fun-box-btn {
      width: 100rpx;
      height: 160rpx;
      color: #ffffff;
      border-radius: 20rpx;
      border: 1rpx solid #c0c0c0;
      display: flex;
      align-items: center;
      justify-content: center;
      margin-bottom: 20rpx;
      margin-right: 10rpx;
      text {
        transform: rotate(90deg);
      }
    }
    .clear {
      color: #909399;
      background-color: #f4f4f5;
    }
    .confirm {
      background-color: #409eff;
    }
    .cancel {
      background-color: #f67d7d;
    }
  }
}
</style>

子组件使用

    <miliu-autograph
      v-model="isCanvas"
      @complete="complete"
    ></miliu-autograph>

let isCanvas = ref(false)


function toCanvas() {
  isCanvas.value = true
}

// 确认事件
const complete = (e) => {
  console.log(e) // 返回本地生成的base图片路径
  // 上传签名图片
  uni.getImageInfo({
    src: e,
    success: function (res) {
      // uni.uploadFile({
      //   url: baseUrl + '/file/upload', //后端接口地址
      //   name: 'file', //必填 , 此为类型名称
      //   filePath: res.path, //电子签名图片路径
      //   header: {
      //     Authorization: 'Bearer ' + that.token
      //   },
      //   success: (res) => {
      //     console.log(res, '签名信息 ------ res');
      //     //上传成功后逻辑
      //     uni.showToast({
      //       title: '签名成功!'
      //     });
      //   },
      //   fail: (err) => {
      //     console.log(err);
      //     uni.showToast({
      //       title: '签名失败!'
      //     });
      //   }
      // });
    }
  })
}

再具体的我就不描述了