uniapp+vue3，签字功能

在uniapp+vue3环境中实现签字功能，可以使用HTML5的canvas元素。以下是一个基本的签字组件示例：

<template>
  <view class="signature-pad">
    <canvas canvas-id="signature-canvas" @touchstart="startSign" @touchmove="continueSign" @touchend="endSign"></canvas>
  </view>
</template>
 
<script setup>
import { ref } from 'vue';
 
const isSigning = ref(false);
const lastPoint = ref(null);
const canvas = ref(null);
const ctx = ref(null);
 
const startSign = (event) => {
  isSigning.value = true;
  const touch = event.touches[0];
  const canvasRect = canvas.value.getBoundingClientRect();
  const point = {
    x: touch.clientX - canvasRect.left,
    y: touch.clientY - canvasRect.top
  };
  ctx.value.beginPath();
  ctx.value.moveTo(point.x, point.y);
  lastPoint.value = point;
};
 
const continueSign = (event) => {
  if (isSigning.value && lastPoint.value) {
    const touch = event.touches[0];
    const canvasRect = canvas.value.getBoundingClientRect();
    const point = {
      x: touch.clientX - canvasRect.left,
      y: touch.clientY - canvasRect.top
    };
    ctx.value.lineTo(point.x, point.y);
    ctx.value.stroke();
    lastPoint.value = point;
  }
};
 
const endSign = () => {
  isSigning.value = false;
  ctx.value.closePath();
};
 
onMounted(() => {
  canvas.value = uni.createSelectorQuery().select('#signature-canvas');
  canvas.value.width = 300;
  canvas.value.height = 150;
  ctx.value = canvas.value.getContext('2d');
  ctx.value.strokeStyle = 'black';
  ctx.value.lineWidth = 3;
  ctx.value.lineCap = 'round';
});
</script>
 
<style scoped>
.signature-pad {
  position: relative;
  width: 300px;
  height: 150px;
  background-color: #fff;
}
 
canvas {
  width: 100%;
  height: 100%;
  touch-action: none;
}
</style>

在这个组件中，我们创建了一个canvas元素，并在onMounted生命周期钩子中初始化它。我们监听触摸事件来处理签名的起点、移动和终点。当用户开始签名时，我们记录下起点坐标，并开始在canvas上绘制路径。在用户移动手指时，我们继续在canvas上绘制线条。当用户签名结束时，我们关闭路径。

这个简单的签名组件可以满足基本的签名需求，但你可能需要添加额外的功能，比如清除签名、保存签名为图片等。