需求：上传图片之前按比例缩小图片分辨率，宽高不超过1920不处理图片，宽高超过1920则缩小图片分辨率，如果是一张图片请参考这篇博客：js实现图片压缩、分辨率等比例缩放
我根据这篇博主的分享，写下了我的循环上传的分辨率等比缩小
功能：点击+号，新增一项，点击- 号 删除一项

:auto-upload="false" 使用elementUI组件不能使他自动上传，主要功能是上传最左边的图片

 <el-form ref="form" :model="form"  label-width="120px"><el-form-item label="资源列表："><div class="ziyuan" flex v-for="(item, indexes) in  addList " :key="item.idxxx"><div style="margin-top: 9px;">//图片(主要功能在这里)<el-upload :action="domins + '/common/upload'":class="{ disabled: item.uploadDisabled }" list-type="picture-card":auto-upload="false":on-remove="handleRemove.bind(null, { 'index': indexes, 'data': item })":on-change="handleChange.bind(null, { 'index': indexes, 'data': item })":file-list="item.fileList" accept="image/png, image/jpeg"><i class="el-icon-plus"></i></el-upload><el-dialog :visible.sync="dialogVisible"><img width="100%" :src="item.dialogImageUrl" alt=""></el-dialog></div><div class="yasuo" flex="cross:center"><div><div style="height: 68px;">//压缩包<el-upload ref="uploadzip" :action="domins + '/common/upload'":before-upload="beforeUploadZip" :on-remove="handleRemoveZip":on-success="handleAvatarSuccessZip.bind(null, { 'index': indexes, 'data': item })":file-list="item.fileListZip" :auto-upload="true" accept=".zip ,.mp4":limit="1"><el-button size="small" type="primary">选择资源包</el-button></el-upload></div></div></div><div class="airadio"><el-radio-group v-model="item.way" ><el-radio :label="0">Android</el-radio><el-radio :label="1">ios</el-radio><el-radio :label="2">视频</el-radio></el-radio-group></div><div style="margin-top: 11px;">//  '+'<i class="el-icon-circle-plus-outline" style="color: #264E71;"@click="plusOne(indexes)"></i>//  '+'<i class="el-icon-remove-outline" style="color: #264E71;" v-show="addList.length > 1"@click="removeOne(indexes, item.id, item)"></i></div></div></el-form-item></el-form>

代码：

<script>
// 等比例缩小图片
function imageScale(width, originWidth, originHeight) {const scaleRatio = width / originWidth;const scaleHeight = scaleRatio * originHeight;return [width, scaleHeight];
}export default {components: {  },data() {return {form: {},addList: [{id: 0,uploadDisabled: false,album: '',zip: '',way: 0,idxxx: 0}],}},methods:{handleRemove(obj, file, fileList) {let index = obj.index;this.addList[index].uploadDisabled = falsethis.$forceUpdate()},// 处理图片compress(file, scaleWidth, quality = 0.5) {return new Promise((resolve, reject) => {const reader = new FileReader();console.log(file, 'file----');reader.readAsDataURL(file.raw);reader.onload = (e) => {let img = new Image();img.src = e.target.result;img.onload = function () {// 等比例缩放图片const [width, height] = imageScale(scaleWidth,img.width,img.height);let canvas = document.createElement("canvas");img.width = canvas.width = width;img.height = canvas.height = height;let ctx = canvas.getContext("2d");ctx.drawImage(img, 0, 0, img.width, img.height);canvas.toBlob((blob) => {resolve(blob);},"image/jpeg",quality);};img.onerror = function () {reject();};};});},handleChange(obj, file, fileList) {console.log(file, fileList, 'file, fileList识别图路径');if (fileList.length >= 1) {let reader = new FileReader()reader.readAsDataURL(file.raw) // 必须用file.rawreader.onload = () => {let img = new Image()img.src = reader.resultimg.onload = () => {console.log(img.width, 'img.width');console.log(img.height, 'img.height');// 宽高超过1920则缩小图片分辨率if (img.width > 1920 || img.width == 1920 || img.height > 1920 || img.height == 1920) {this.compress(file, 1024).then((blob) => {// 根据后端的要求传数据，如果要求是blob，则不需要处理数据，我这边需求是上传file文件流//处理成file文件流 let f = new File([blob], 'image.jpg', { type: 'image/jpeg' })var form = {};form = new FormData();form.append('file', f);this.$axios.post(this.domins + '/common/upload', form).then((res) => {let index = obj.index;this.addList[index].uploadDisabled = truethis.addList[index].album = res.data.data.fullurlconsole.log(this.addList, '==addList==');})});} else {//宽高不超过1920不处理图片let form = {};form = new FormData();// form 需要的是el-upload 中的file.rowform.append('file', file.raw);this.$axios.post(this.domins + '/common/upload', form).then((res) => {let index = obj.index;this.addList[index].uploadDisabled = truethis.addList[index].album = res.data.data.fullurlconsole.log(this.addList, '==addList=3333=');})}}}}},}
}
</script>