需求：用户需要手写签名（需要带笔锋）

思路：可以使用smooth-signature实现，越用力写出的字越粗

如下是效果图：

一、安装 smooth-signature

yarn add smooth-signature
或者
npm install smooth-signature

二、封装组件，方便复用

通过finally事件将签字内容传递出去。

<template>
  <div class="sign-finish">
    <div class="wrap1" v-show="isHorizontal">
      <p class="sign-title">请在区域内签字</p>
      <canvas class="canvas1" ref="canvas1" />
      <div class="actions">
        <van-button class="danger" @click="handleClear(1)">清除</van-button>
        <van-button class="warning" @click="revoked(1)">撤销</van-button>
        <van-button class="primary" @click="handleFull">横屏</van-button>
        <van-button class="success" @click="save(1)">保存</van-button>
      </div>
    </div>
    <div class="wrap2" v-show="!isHorizontal">
      <div class="actionsWrap">
        <div class="actions">
          <van-button class="danger" @click="handleClear(2)">清除</van-button>
          <van-button class="warning" @click="revoked(2)">撤销</van-button>
          <van-button class="primary" @click="handleFull">竖屏</van-button>
          <van-button class="success" @click="save(2)">保存</van-button>
        </div>
      </div>
      <canvas  class="canvas" ref="canvas2" />
    </div>
  </div>
</template>

<script>
import SmoothSignature from "smooth-signature";
import { Toast } from "vant";
export default {
  name: "signatureMenu",
  data() {
    return {
      isHorizontal: false,
      signature1: null,
      signature2: null,
    };
  },
  mounted() {
    this.initSignature();
  },
  methods: {
    initSignature() {
      const canvas1 = this.$refs.canvas1;
      const canvas2 = this.$refs.canvas2;
      const options1 = {
        width: window.innerWidth - 30,
        height: 200,
        minWidth: 2,
        maxWidth: 6,
        openSmooth: true,
        bgColor: "#f6f6f6",
      };
      const options2 = {
        width: window.innerWidth - 120,
        height: window.innerHeight - 80,
        minWidth: 3,
        maxWidth: 10,
        openSmooth: true,
        bgColor: "#f6f6f6",
      };
      this.signature1 = new SmoothSignature(canvas1, options1);
      this.signature2 = new SmoothSignature(canvas2, options2);
    },

    handleClear() {
      this.signature1.clear();
      this.signature2.clear();
    },
    revoked(type = 1) {
      this[`signature${type}`].undo();
    },
    handleFull() {
      this.isHorizontal = !this.isHorizontal;
      this.handleClear();
    },
    save(type = 1) {
      const isEmpty = this[`signature${type}`].isEmpty();
      if (isEmpty) {
        Toast.fail(`请先完成签字`);
        return;
      }
      // const pngUrl = this[`signature${type}`].getPNG();
      const pngUrl = this[`signature${type}`].toDataURL();
      this.$emit("finally", pngUrl);
      console.log(pngUrl);
    },
  },
};
</script>

<style lang="scss" scoped>
.sign-finish {
  text-align: center;
  height: 100%;
  box-sizing: border-box;
  width: 100%;
  button {
    height: 32px;
    padding: 0 8px;
    font-size: 12px;
    border-radius: 2px;
  }
  .danger {
    color: #fff;
    background: #ee0a24;
    border: 1px solid #ee0a24;
  }
  .warning {
    color: #fff;
    background: #ff976a;
    border: 1px solid #ff976a;
  }
  .primary {
    color: #fff;
    background: #1989fa;
    border: 1px solid #1989fa;
  }
  .success {
    color: #fff;
    background: #07c160;
    border: 1px solid #07c160;
  }
  canvas {
    border-radius: 10px;
    border: 2px dashed #ccc;
  }
  .wrap1 {
    height: 100%;
    width: 96%;
    margin: auto;
    margin-top: 100px;
    .actions {
      display: flex;
      justify-content: space-around;
    }
  }
  .wrap2 {
    padding: 15px;
    height: 100%;
    display: flex;
    justify-content: center;
    .actionsWrap {
      width: 50px;
      display: flex;
      justify-content: center;
      align-items: center;
    }
    .canvas {
      flex: 1;
      margin: auto;
    }
    .actions {
      margin-right: 10px;
      white-space: nowrap;
      transform: rotate(90deg);
      button {
        margin-right: 20px;
      }
    }
  }
}
</style>