Vue集成vue-esign电子签名组件与移动端Canvas实现方案

npm install vue-esign --save

import vueEsign from 'vue-esign'
Vue.use(vueEsign)

<template>
  <div class="esigns">
    <vue-esign
      ref="esign"
      style="
        width: 100%;
        height: 400px
      "
      :isCrop="isCrop"
      :lineWidth="lineWidth"
      :lineColor="lineColor"
      :bgColor.sync="bgColor"
    />
    <div class="btn">
      <van-button type="primary" @click="handleReset">重置</van-button>
      <van-button type="info" @click="handleGenerate">确定</van-button>
    </div>
  </div>
</template>

<script>
export default {
  name: "Esign",
  data() {
    return {
      lineWidth: 6,
      lineColor: "#000000",
      bgColor: "",
      resultImg: "",
      isCrop: false,
    };
  },
  methods: {
    handleReset() {
      // 清除
      this.$refs.esign.reset();
    },
    handleGenerate() {
      // 获取base64
      var _this = this;
      _this.$refs.esign
        .generate()
        .then((res) => {
          // 转成文件
          var file = _this.dataURLtoFile(res);
            console.log("file:",file )
          //调用接口
          uploadFile(file).then(({ data }) => {
           console.log("data:",data)
          });
        })
        .catch((err) => {
          _this.$toast(err); 
        });
    },
    // 将base64转换为file
    dataURLtoFile(dataurl) {
      let arr = dataurl.split(",");
      let mime = arr[0].match(/:(.*?);/)[1];
      let bytes = atob(arr[1]); // 解码base64
      let n = bytes.length;
      let ia = new Uint8Array(n);
      while (n--) {
        ia[n] = bytes.charCodeAt(n);
      }
      return new File([ia], "easign.jpg", { type: mime });
    },
  },
};
</script>

<style scoped>
.btn {
  display: flex;
  justify-content: space-around;
  margin-top: 10px;
}
</style>

<template>
    <div id='canvasBox'>
        <div ref="canvasBox">
             <canvas id="canvas" ref="canvas" height="150"></canvas>
        </div>
        <div class="row row-space-between">
          <button  @click="onClickCancle">取消</button>
          <button @click="clear">重签</button>
          <button @click="save">确认</button>
        </div>
        <!-- <img :src="singImgUrl" alt /> -->
    </div>
</template>

<script>
var draw;
var preHandler = function(e) {
  e.preventDefault();
};
class Draw {
  constructor(el) {
    this.el = el;
    this.canvas = document.getElementById(this.el);
    this.cxt = this.canvas.getContext("2d");
    this.stage_info = canvas.getBoundingClientRect();
    this.path = {
      beginX: 0,
      beginY: 0,
      endX: 0,
      endY: 0
    };
  }
  init(btn) {
    var that = this;
    this.canvas.addEventListener("touchstart", function(event) {
      document.addEventListener("touchstart", preHandler, false);
      that.drawBegin(event);
    });
    this.canvas.addEventListener("touchend", function(event) {
      document.addEventListener("touchend", preHandler, false);
      that.drawEnd();
    });
    this.clear(btn);
  }
  drawBegin(e) {
    var that = this;
    window.getSelection()
      ? window.getSelection().removeAllRanges()
      : document.selection.empty();
    this.cxt.strokeStyle = "#BC4C2D";
    this.cxt.beginPath();
    this.cxt.moveTo(
      e.changedTouches[0].clientX - this.stage_info.left,
      e.changedTouches[0].clientY - this.stage_info.top
    );
    this.path.beginX = e.changedTouches[0].clientX - this.stage_info.left;
    this.path.beginY = e.changedTouches[0].clientY - this.stage_info.top;
    canvas.addEventListener("touchmove", function() {
      that.drawing(event);
    });
  }
  drawing(e) {
    this.cxt.lineTo(
      e.changedTouches[0].clientX - this.stage_info.left,
      e.changedTouches[0].clientY - this.stage_info.top
    );
    this.path.endX = e.changedTouches[0].clientX - this.stage_info.left;
    this.path.endY = e.changedTouches[0].clientY - this.stage_info.top;
    this.cxt.stroke();
  }
  drawEnd() {
    document.removeEventListener("touchstart", preHandler, false);
    document.removeEventListener("touchend", preHandler, false);
    document.removeEventListener("touchmove", preHandler, false);
    //canvas.ontouchmove = canvas.ontouchend = null
  }
  clear(btn) {
    this.base64Id = "";
    this.cxt.clearRect(0, 0, 500, 600);
  }
  save() {
    var blank = document.createElement("canvas"); //系统获取一个空canvas对象
    blank.width = canvas.width;
    blank.height = canvas.height;
    let flag = canvas.toDataURL("image/png") == blank.toDataURL(); //比较值相等则为空;
    if (flag) {
      return "0";
    } else {
      return canvas.toDataURL("image/png");
    }
  }
}
export default {
  data() {
    return {
      singImgUrl: ""
    };
  },
  methods: {
	 clear() {
        draw.clear();
        this.base64Id = "";
	 },
   	save() {
      var data = "";
      data = draw.save();
      if (data == "0") {
      		this.$toast("请先签名再点击确定哦~");
      } else {
	      this.singImgUrl = data;
	      ///data 就是得到的base64格式的签名图片，根据业务这里可上传到服务器
      }
      // 
    },
}，
 mounted() {
 document.getElementById("canvasBox").addEventListener("touchmove", (e) => {
      e.preventDefault();
    });//阻止浏览器默认行为，防止签名浏览器下拉-------很重要
    this.base64Id = "";
    let _width = this.$refs.canvasBox.offsetWidth;
    this.$refs.canvas.width = _width; //适配移动端宽度给canvas
    draw = new Draw("canvas");
    draw.init();
  }
}
</script>