ECharts在Vue中实现打印功能

我不是女神ヾ 2021-09-23 08:14 1013阅读 0赞

*前言：在Vue中利用自带的页面打印是打印不出ECharts图表的，原因是获取不到ECharts插件的css节点。打印出来的结果会是空白。经过参考了网上的多篇文档，总结步骤阐述了一下，希望为大家提供一点小小帮助。*  
1.在Vue项目中某个文件夹下创建一个print.js的文件，文件内容为：

// 打印类属性、方法定义
    /* eslint-disable */
    const Print = function (dom, options) {
      if (!(this instanceof Print)) return new Print(dom, options);
     
      this.options = this.extend({
        'noPrint': '.no-print'
      }, options);
     
      if ((typeof dom) === "string") {
        this.dom = document.querySelector(dom);
      } else {
        this.isDOM(dom)
        this.dom = this.isDOM(dom) ? dom : dom.$el;
      }
     
      this.init();
    };
    Print.prototype = {
      init: function () {
        var content = this.getStyle() + this.getHtml();
        this.writeIframe(content);
      },
      extend: function (obj, obj2) {
        for (var k in obj2) {
          obj[k] = obj2[k];
        }
        return obj;
      },
     
      getStyle: function () {
        var str = "",
          styles = document.querySelectorAll('style,link');
        for (var i = 0; i < styles.length; i++) {
          str += styles[i].outerHTML;
        }
        str += "<style>" + (this.options.notPrint ? this.options.notPrint : '.no-print') + "{display:none;}</style>";
        str += "<style>.results{width:100%!important;} .result .title{width:100%;}</style>";
     
        return str;
      },
     
      getHtml: function () {
        var inputs = document.querySelectorAll('input');
        var textareas = document.querySelectorAll('textarea');
        var selects = document.querySelectorAll('select');
        var canvass = document.querySelectorAll('canvas');
        for (var k = 0; k < inputs.length; k++) {
          if (inputs[k].type == "checkbox" || inputs[k].type == "radio") {
            if (inputs[k].checked == true) {
              inputs[k].setAttribute('checked', "checked")
            } else {
              inputs[k].removeAttribute('checked')
            }
          } else if (inputs[k].type == "text") {
            inputs[k].setAttribute('value', inputs[k].value)
          } else {
            inputs[k].setAttribute('value', inputs[k].value)
          }
        }
     
        for (var k2 = 0; k2 < textareas.length; k2++) {
          if (textareas[k2].type == 'textarea') {
            textareas[k2].innerHTML = textareas[k2].value
          }
        }
     
        for (var k3 = 0; k3 < selects.length; k3++) {
          if (selects[k3].type == 'select-one') {
            var child = selects[k3].children;
            for (var i in child) {
              if (child[i].tagName == 'OPTION') {
                if (child[i].selected == true) {
                  child[i].setAttribute('selected', "selected")
                } else {
                  child[i].removeAttribute('selected')
                }
              }
            }
          }
        }
        //canvass echars图表转为图片
        for (var k4 = 0; k4 < canvass.length; k4++) {
          var imageURL = canvass[k4].toDataURL("image/png");
          var img = document.createElement("img");
          img.src = imageURL;
          img.setAttribute('style', 'max-width: 100%;');
          img.className = 'isNeedRemove'
          // canvass[k4].style.display = 'none'
          // canvass[k4].parentNode.style.width = '100%'
          // canvass[k4].parentNode.style.textAlign = 'center'
          canvass[k4].parentNode.insertBefore(img,canvass[k4].nextElementSibling);
        }
        //做分页
        //style="page-break-after: always"
        var pages = document.querySelectorAll('.content');
        for (var k5 = 0; k5 < pages.length; k5++) {
          pages[k5].setAttribute('style', 'page-break-after: always');
        }
        return this.dom.outerHTML;
      },
     
      writeIframe: function (content) {
        var w, doc, iframe = document.createElement('iframe'),
          f = document.body.appendChild(iframe);
        iframe.id = "myIframe";
        //iframe.style = "position:absolute;width:0;height:0;top:-10px;left:-10px;";
        iframe.setAttribute('style', 'position:absolute;width:' + document.querySelector('#seven').clientWidth + 'px;height:0;top:-10px;left:-10px;');
        w = f.contentWindow || f.contentDocument;
        doc = f.contentDocument || f.contentWindow.document;
        doc.open();
        doc.write(content);
        doc.close();
     
        var removes = document.querySelectorAll('.isNeedRemove');
        for (var k = 0; k < removes.length; k++) {
          removes[k].parentNode.removeChild(removes[k]);
        }
     
        var _this = this
        iframe.onload = function(){
          _this.toPrint(w);
          setTimeout(function () {
            document.body.removeChild(iframe)
          }, 100)
        }
      },
     
      toPrint: function (frameWindow) {
        try {
          setTimeout(function () {
            frameWindow.focus();
            try {
              if (!frameWindow.document.execCommand('print', false, null)) {
                frameWindow.print();
              }
            } catch (e) {
              frameWindow.print();
            }
            frameWindow.close();
          }, 10);
        } catch (err) {
          console.log('err', err);
        }
      },
      isDOM: (typeof HTMLElement === 'object') ?
        function (obj) {
          return obj instanceof HTMLElement;
        } :
        function (obj) {
          return obj && typeof obj === 'object' && obj.nodeType === 1 && typeof obj.nodeName === 'string';
        }
    };
    const MyPlugin = {}
    MyPlugin.install = function (Vue, options) {
      // 4. 添加实例方法
      Vue.prototype.$print = Print
    }
    export default MyPlugin

2.在main.js中要进行注册发现，可供全局使用。下面是我的代码

import print from './http/print'
    Vue.use(print)

3.在ECharts页面中，自定义自己的打印方法

<el-button type="info" @click="printTest()" plain>打印</el-button>		//打印按钮
    printTest(){		//打印方法
    	this.$print(this.$refs.print,{'notPrint':'.el-button, .el-select'})
    			}

4.特别注意事项：  
在print.js中 var pages = document.querySelectorAll(’.content’);与document.querySelector(’\#seven’).clientWidth + ‘px;height:0;top:-10px;left:-10px;’);  
的.content与\#seven是要修改自己页面自定义的选择器。

这里贴上我的选择的器位置，大家一定要注意上面两个选择器在div中的嵌套关系

<template>
    	<div class="content" id="print" ref="print">
       <div class="block">
    
         <el-date-picker
          v-model="value2"
          type="datetimerange"
    	  format="yyyy-MM-dd HH:mm:ss"
          :picker-options="pickerOptions"
          range-separator="至"
          start-placeholder="开始日期"
          end-placeholder="结束日期"
          >
        </el-date-picker>
    
    	<el-button type="info" @click="dt()">查询</el-button>
    	<el-button type="info" @click="printTest()" plain>打印</el-button>
    
      </div>
    		
    		<div style="height:580px;"  id="seven"> 
    		</div>
    	</div>
    	
    </template>

参考的文档：  
https://blog.csdn.net/shishuwei111/article/details/94167974\#comments  
对他也表示感谢！