vue之原生上传图片加水印并压缩图片大小

安装相应插件

npm i -S  compressorjs
npm i -S  html2canvas

封装添加水印的方法

import Compressor from "compressorjs";
import html2canvas from "html2canvas";

/**
 * 压缩和旋转图片
 * @param {blob} file
 * @param {number} quality  压缩比例
 * @param {number} maxWidth 图片最大宽度
 * @returns {Promise}
 */
export function compressor(file, drew, maxWidth = 750, quality = 0.6) {
  return new Promise((resolve) => {
    new Compressor(file, {
      strict: false,
      maxWidth,
      quality,
      drew,
      success: resolve,
      error(err) {
        console.log(err.message);
      },
    });
  });
}

/**
 * 添加水印
 * @param {blob} file
 * @param {string} el
 * @returns {Promise}
 */
export async function addWaterMarker(file, el = "#markImg", direction = "rightDown") {
  return new Promise(async (resolve, reject) => {
    try {
      const maxWidth = 750;
      const img = await blobToImg(file);
      console.log(img.naturalWidth);
      const imgWidth = img.naturalWidth > maxWidth ? maxWidth : img.naturalWidth;

      // 生成水印图片
      const markEle = document.querySelector(el);
      const scale = (imgWidth * 0.25) / markEle.clientWidth;
      // 先缩放水印再转成图片
      markEle.style.transform = `scale(${scale})`;
      const markImg = await htmlToCanvas(markEle);

      // 先压缩和旋转图片
      file = await compressor(
        file,
        (context, canvas) => {
          if (direction == "rightDown") {
            // 填充水印 右下角
            context.drawImage(markImg, canvas.width - markImg.width - 15 * scale, canvas.height - markImg.height - 15 * scale, markImg.width, markImg.height);
          } else {
            // 填充水印 左下角
            context.drawImage(markImg, 15 * scale, canvas.height - markImg.height - 15 * scale, markImg.width, markImg.height);
          }
        },
        maxWidth
      );
      resolve(file);
    } catch (error) {
      reject(error);
    }
  });
}

function blobToImg(blob) {
  return new Promise((resolve, reject) => {
    let reader = new FileReader();
    reader.addEventListener("load", () => {
      let img = new Image();
      img.src = reader.result;
      img.addEventListener("load", () => resolve(img));
    });
    reader.readAsDataURL(blob);
  });
}

export function htmlToCanvas(el, backgroundColor = "rgba(0,0,0,.1)") {
  return new Promise(async (resolve, reject) => {
    try {
      const markImg = await html2canvas(el, {
        scale: 2,
        allowTaint: false, //允许污染
        useCORS: true,
        backgroundColor, //'transparent'  //背景色
      });
      resolve(markImg);
    } catch (error) {
      reject(error);
    }
  });
}

上传图片，回显图片

<template>
  <div class="content-box">
    <div class="container">
      <div class="title">点击上传图像（支持image/jpg,image/jpeg,image/png,image/gif格式图片且大小不能超过10MB）</div>
      <div class="uploadImg">
        <span class="el-icon-plus"></span>
        <input :accept="accept" type="file" class="upload_ipu" ref="fileLoad" @change="uploadImg" />
      </div>
      <div class="imgList">
        <img v-if="imgShow" :src="imgSrc" />
      </div>
      <img v-if="imgShow" :src="fileUrl" />
      <!-- 图片上传水印 -->
      <div id="markImg">
        <div class="logo">
          图片水印：
          <img src="@/assets/logo.png" />
        </div>
        <p>文字水印：{{ loginName }}</p>
      </div>
    </div>
  </div>
</template>

<script>
import { compressor, addWaterMarker } from "../utils/imageUtils.js";
import apis from "@/api";
const {
  commonSys: { commonUploadFile },
} = apis;
export default {
  props: {
    accept: {
      type: String,
      default: "image/jpg,image/jpeg,image/png,image/gif",
    },
  },
  data() {
    return {
      imgShow: false,
      imgSrc: "",
      loginName: "fqniu",
      fileDate: new Date(),
      needWaterMark: true,
      fileUrl: "",
    };
  },
  // created() {
  //   this.parseTime = parseTime
  // },
  methods: {
    createUrl(file) {
      if (window.URL) {
        return window.URL.createObjectURL(file);
      } else if (window.webkitURL) {
        return window.webkitURL.createObjectURL(file);
      } else {
        return null;
      }
    },
    async uploadImg() {
      // 这个是元素dom节点
      console.log(this.$refs.fileLoad);
      // 上传文件fileList
      console.log(this.$refs.fileLoad.files);
      let file = this.$refs.fileLoad.files[0];
      let size = file.size / 1024 / 1024;
      console.log(file, file.lastModifiedDate);
      if (!this.accept.includes(file.type.toLowerCase())) {
        this.$message.error("图片格式不正确!");
        return false;
      }
      if (size > 10) {
        this.$message.error("图片大小不能超过10MB!");
        return false;
      }
      // 压缩图片
      // if (file.size > 512 * 1024 && file.type.includes("image/")) {
      //   file = await compressor(file);
      // }
      // 添加水印
      if (this.needWaterMark) {
        const fileName = file.name;
        file = await addWaterMarker(file, "#markImg", "leftDown");
        file.name = fileName;
      }
      this.imgSrc = this.createUrl(file);
      console.log(this.imgSrc);
      console.log(file);
      this.httpRequest(file);
      this.$message.success("上传成功！");
    },
    httpRequest(fileObj) {
      // let fileObj = param.file; // 相当于input里取得的files
      console.log(fileObj);
      let fd = new FormData(); // FormData 对象
      fd.append("file", fileObj); // 文件对象
      commonUploadFile("qms", fd).then((res) => {
        console.log(res.fileUrl);
        this.fileUrl = res.fileUrl;
        this.imgShow = true;
      });
    },
  },
};
</script>

<style lang="scss" scoped>
.container {
  margin: 50px;
}
.title {
  font-size: 16px;
  color: #73777b;
}
.uploadImg {
  margin-top: 20px;
  border: 1px dashed #d9d9d9;
  border-radius: 6px;
  cursor: pointer;
  position: relative;
  overflow: hidden;
  width: 180px;
  height: 180px;
  transition: all 0.2s;
  background: #fff;
  &:hover {
    border-color: #409eff;
  }
  span {
    font-size: 28px;
    color: #8c939d;
    width: 178px;
    height: 178px;
    line-height: 178px;
    text-align: center;
  }
  .upload_ipu {
    opacity: 0;
    width: 100%;
    height: 100%;
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    z-index: 2;
  }
  img {
    width: 178px;
    height: 178px;
    position: absolute;
    border-radius: 6px;
    left: 0;
    top: 0;
    z-index: 1;
  }
}
.imgList {
  width: 550px;
  height: 400px;
  img {
    width: 100%;
    height: 100%;
  }
}
// 水印样式
#markImg {
  position: absolute;
  left: -9999999px;
  text-align: left;
  padding: 10px 15px;
  .logo {
    font-weight: 600;
    font-size: 15px;
    color: #ffffff;
    display: flex;
    height: 21px;
    align-items: center;
    justify-content: flex-start;
    img {
      height: 21px;
      margin-right: 5px;
    }
  }
  p {
    margin-top: 6px;
    color: #ffffff;
    font-size: 12px;
    font-weight: 400;
  }
}
</style>