vue3 el-upload 在上传前自动压缩图片大小

<template> <div class="component-upload-image"> <el-upload multiple :action="uploadImgUrl" list-type="picture-card" :on-success="handleUploadSuccess" :before-upload="handleBeforeUpload" :limit="limit" :on-error="handleUploadError" :on-exceed="handleExceed" ref="imageUpload" :before-remove="handleDelete" :show-file-list="true" :headers="headers" :file-list="fileList" :on-preview="handlePictureCardPreview" :class="{ hide: fileList.length >= limit }" > <el-icon class="avatar-uploader-icon"><plus /></el-icon> </el-upload> <!-- 上传提示 --> <div class="el-upload__tip" v-if="showTip"> 请上传 <template v-if="fileSize"> 大小不超过 <b style="color: #f56c6c">200KB</b> </template> <template v-if="fileType"> 格式为 <b style="color: #f56c6c">{{ fileType.join("/") }}</b> </template> 的文件 </div> <el-dialog v-model="dialogVisible" title="预览" width="800px" append-to-body > <img :src="dialogImageUrl" style="display: block; max-width: 100%; margin: 0 auto" /> </el-dialog> </div> </template> <script setup> import { getToken } from "@/utils/auth"; import { compressAccurately } from 'image-conversion' const props = defineProps({ modelValue: [String, Object, Array], // 图片数量限制 limit: { type: Number, default: 1, }, // 大小限制(MB) fileSize: { type: Number, default: 2, }, // 文件类型, 例如['png', 'jpg', 'jpeg'] fileType: { type: Array, default: () => ["png", "jpg", "jpeg"], }, // 是否显示提示 isShowTip: { type: Boolean, default: true }, //文件类型(oss_file_type):头像-avatar 大门照片-door 广告-banner 证件-identity 合同-contract customerId:{ type:String, default:'' }, }); const { proxy } = getCurrentInstance(); const emit = defineEmits(); const number = ref(0); const uploadList = ref([]); const dialogImageUrl = ref(""); const dialogVisible = ref(false); const baseUrl = ''; const uploadImgUrl = ref(import.meta.env.VITE_APP_BASE_API + `/common/image/upload/faceImg?customerId=${props.customerId}`); // 上传的图片服务器地址 const headers = ref({ Authorization: "Bearer " + getToken() }); const fileList = ref([]); const showTip = computed( () => props.isShowTip && (props.fileType || props.fileSize) ); watch(() => props.modelValue, val => { if (val) { // 首先将值转为数组 const list = Array.isArray(val) ? val : props.modelValue.split(","); // 然后将数组转为对象数组 fileList.value = list.map(item => { if (typeof item === "string") { if (item.indexOf(baseUrl) === -1) { item = { name: baseUrl + item, url: baseUrl + item }; } else { item = { name: item, url: item }; } } return item; }); } else { fileList.value = []; return []; } },{ deep: true, immediate: true }); // 转base64 function base64ConvertFile(urlData) { var arr = urlData.split(',') var type = arr[0].match(/:(.*?);/)[1] var fileExt = type.split('/')[1] var bstr = atob(arr[1]) var n = bstr.length var u8arr = new Uint8Array(n) while (n--) { u8arr[n] = bstr.charCodeAt(n); } return new File([u8arr], `${(Math.random() + '').replace('.', '')}.` + fileExt, { type: type }); } // 压缩图片 function compressFile(file){ return new Promise((resolve, reject) => { let reader = new FileReader(); reader.readAsDataURL(file); reader.onload = (e) => { // 图片base64化 const base64Str = e.target.result; // 转化后的base64字符串 const img = new Image(); img.src = base64Str; img.onload = () => { // 获取 canvas 元素 let canvas = document.getElementById("uploadFileCanvas"); if (!canvas) { let pobj = document.getElementsByTagName("body")[0]; let canvasTag = document.createElement("canvas"); canvasTag.style.display = "none"; canvasTag.id = "uploadFileCanvas"; pobj.appendChild(canvasTag); canvas = document.getElementById("uploadFileCanvas"); } // 绘制图像到 canvas 有指定宽度用this.width，没有就用图片的原宽高 canvas.width = img.width; canvas.height = img.height; let ctx = canvas.getContext("2d"); ctx.drawImage(img, 0, 0, canvas.width, canvas.height); // 使用 toDataURL 方法压缩图像 let dataUrl = canvas.toDataURL("image/jpeg", 0.8); resolve(base64ConvertFile(dataUrl)) }; }; }); } // 上传前loading加载 function handleBeforeUpload(file) { let isImg = false; if (props.fileType.length) { let fileExtension = ""; if (file.name.lastIndexOf(".") > -1) { fileExtension = file.name.slice(file.name.lastIndexOf(".") + 1); } isImg = props.fileType.some(type => { if (file.type.indexOf(type) > -1) return true; if (fileExtension && fileExtension.indexOf(type) > -1) return true; return false; }); } else { isImg = file.type.indexOf("image") > -1; } if (!isImg) { proxy.$modal.msgError( `文件格式不正确, 请上传${props.fileType.join("/")}图片格式文件!` ); return false; } if (props.fileSize) { const isLt = file.size / 1024 / 1024 < props.fileSize; if (!isLt) { proxy.$modal.msgError(`上传头像图片大小不能超过 ${props.fileSize} MB!`); return false; } } // 上传前压缩图片 const compressedFile = compressFile(file); // 执行上传 proxy.$modal.loading("正在上传图片，请稍候..."); number.value++; return compressedFile; } // 文件个数超出 function handleExceed() { proxy.$modal.msgError(`上传文件数量不能超过 ${props.limit} 个!`); } // 上传成功回调 function handleUploadSuccess(res, file) { if (res.code === 200) { uploadList.value.push({ name: res.data, url: res.data }); uploadedSuccessfully(); } else { number.value--; proxy.$modal.closeLoading(); proxy.$modal.msgError(res.msg); proxy.$refs.imageUpload.handleRemove(file); uploadedSuccessfully(); } } // 删除图片 function handleDelete(file) { const findex = fileList.value.map(f => f.name).indexOf(file.name); if (findex > -1 && uploadList.value.length === number.value) { fileList.value.splice(findex, 1); emit("update:modelValue", listToString(fileList.value)); return false; } } // 上传结束处理 function uploadedSuccessfully() { if (number.value > 0 && uploadList.value.length === number.value) { fileList.value = fileList.value.filter(f => f.url !== undefined).concat(uploadList.value); uploadList.value = []; number.value = 0; emit("update:modelValue", listToString(fileList.value)); proxy.$modal.closeLoading(); } } // 上传失败 function handleUploadError() { proxy.$modal.msgError("上传图片失败"); proxy.$modal.closeLoading(); } // 预览 function handlePictureCardPreview(file) { console.log(file,'file') dialogImageUrl.value = file.url; dialogVisible.value = true; } // 对象转成指定字符串分隔 function listToString(list, separator) { let strs = ""; separator = separator || ","; for (let i in list) { if (undefined !== list[i].url && list[i].url.indexOf("blob:") !== 0) { strs += list[i].url.replace(baseUrl, "") + separator; } } return strs != "" ? strs.substr(0, strs.length - 1) : ""; } </script> <style scoped lang="scss"> // .el-upload--picture-card 控制加号部分 :deep(.hide .el-upload--picture-card) { display: none; } </style>