详情参考:https://www.npmjs.com/package/watermark-package
示例方法

  <el-button type="primary" @click="AddWatermark">添加水印</el-button>
 <el-button type="primary" @click="RemoveWatermark">清除水印</el-button>

const AddWatermark = () => {
  watermark.setWaterMark({
    w_texts: ['娃哈哈', '177****0000'],
    w_options: {
      w_width: 240,
      w_height: 140,
      w_top: '0px',
      w_left: '0px',
      w_rotateDeg: 25,
      w_font: '1.2rem Vedana',
      w_color: 'red',
      w_opacity: '0.2',
      w_zIndex: '100000'
    }
  })
}
const RemoveWatermark = () => {
  watermark.removeWatermark()
}