在基于ABP框架的前端项目Vue&Element项目中采用电子签章处理文件和打印处理

.demoImg{ background-image: url("data:image/jpg;base64,/9j/4QMZRXhpZgAASUkqAAgAAAAL...."); }

<img width="40" height="30" src="data:image/jpg;base64,/9j/4QMZRXhpZgAASUkqAAgAAAAL...." />

我们使用C#代码转换的处理代码如下所示。
private void btnBase64_Click(object sender, EventArgs e)
        {
            var base64 = ImageHelper.ImageToBase64Str(this.pictureBox1.Image);
            if(chkData.Checked)
            {
                base64 = "data:image/jpeg;base64," + base64;
            }
            this.txtBase64.Text = base64;
        }

/// <summary>
        /// 从文件中转换图片对象到Base64编码
        /// </summary>
        /// <param name="imageFilePath">图片文件路径</param>
        /// <returns></returns>
        public static string ImageToBase64Str(string imageFilePath)
        {
            Image image = Image.FromFile(imageFilePath);
            using (MemoryStream ms = new MemoryStream())
            {
                image.Save(ms, image.RawFormat);//ImageFormat.Jpeg
                byte[] imageBytes = ms.GetBuffer();
                string imgBase64Str = Convert.ToBase64String(imageBytes);
                //释放资源，让别的使用
                image.Dispose();
                return imgBase64Str;
            }
        }
        /// <summary>
        /// 转换图片对象到Base64编码
        /// </summary>
        /// <param name="image">Image图片对象</param>
        /// <returns></returns>
        public static string ImageToBase64Str(Image image)
        {
            using (MemoryStream ms = new MemoryStream())
            {
                image.Save(ms, image.RawFormat);//ImageFormat.Jpeg
                byte[] imageBytes = ms.GetBuffer();
                string imgBase64Str = Convert.ToBase64String(imageBytes);
                return imgBase64Str;
            }
        }

import Vue from 'vue'
import VueDragResize from 'vue-drag-resize'
Vue.component('vue-drag-resize', VueDragResize)

import VueDragResize from 'vue-drag-resize'
export default {
  components: { VueDragResize },

<template>
    <div id="app">
        <VueDragResize :isActive="true" :w="200" :h="200" v-on:resizing="resize" v-on:dragging="resize">
            <h3>Hello World!</h3>
            <p>{{ top }} х {{ left }} </p>
            <p>{{ width }} х {{ height }}</p>
        </VueDragResize>
    </div>
</template>

<vue-drag-resize :x="0">

<vue-drag-resize :y="0">

print () {
      const print = this.$refs.print.innerHTML
      const printPart = print + csstyle;
      const newTab = window.open('_blank');
      newTab.document.body.innerHTML = printPart;
      newTab.print();
      newTab.close();
    },

@media print {
  @page {
    margin: 0;
  }
  body {
    margin: 1cm;
  }
}

@page { margin-bottom: 0; }

window.addEventListener('beforeprint', ()=> {
  document.body.innerHTML = '打印前触发';
});
window.addEventListener('afterprint', ()=> {
  document.body.innerHTML = '打印后触发';
});

@media print {
    @page {
      // 纵向
      size: portrait; 
 
     // 横向
      size: landscape;
 
      // 边距
      margin: 0cm 0cm 0cm 0cm;
    }
  }