时间：2021-02-11 11:22:12 | 栏目：vue | 点击：次
一、前言
三年.net开发转前端已经四个月了，前端主要用webpack+vue，由于后端转过来的，前端不够系统，希望分享下开发心得与园友一起学习。
图片的上传之前都是用的插件(ajaxupload)，或者传统上传图片的方式,各有利弊：插件的问题是依赖jq并且会使系统比较臃肿，还有传统的web开发模式 前后端偶尔在一起及对用户体验要求低，现在公司采用webpack+vue+restfullApi开发模式 前后端完全分离，遵从高内聚，低偶尔的原则，开发人员各司其职，一则提升开发效率（从长期来看，短期对于很多开发人员需要有个适应的过程，特别是初中级的前端处理业务逻辑方面的能力比较欠缺），二则提升用户体验。今天分享下在项目开发中写的的图片上传 vue组件。
二、处理问题
这里用h5做图片上传考虑到浏览器支持的问题，这里考虑的场景是在做webapp的时候
1.移动web图片上传还包括拍摄上传，但是在移动端会出现拍摄的照片会旋转，处理这个问题需要得到图片旋转的情况，可以用exif.js来获取，具体可以参看文档
2.图片压缩
3.旋转
三、代码
1组件代码
<template>
<div>
<input type="file" style="display: none;" id="img-upload" multiple accept="image/*" @change="uploadImg($event)"/>
</div>
</template>
<script>
import EXIF from '../../../Resource/Global/Js/exif'
export default{
name:"image-html5-upload",
props:{
imgArr:{
type:Array,
twoWay: true,
default:Array
},
imgNumLimit:{//一次最多可以上传多少张照片
type:Number,
default:4
}
},
methods:{
"uploadImg": function(e){
let tag = e.target;
let fileList = tag.files;
let imgNum = fileList.length;
let _this = this;
_this.imgArr = [];//图片数据清零
if(this.imgArr.length + imgNum > this.imgNumLimit){
alert('一次最多上传'+this.imgNumLimit+'张图片！');
return;
}
var Orientation;
for(let i=0;i<imgNum;i++){
EXIF.getData(fileList[i], function(){
Orientation = EXIF.getTag(fileList[i], 'Orientation');
});
let reader = new FileReader();
reader.readAsDataURL(fileList[i]);
reader.onload = function(){
var oReader = new FileReader();
oReader.onload = function(e) {
var image = new Image();
image.src = e.target.result;
image.onload = function() {
var expectWidth = this.naturalWidth;
var expectHeight = this.naturalHeight;
if (this.naturalWidth > this.naturalHeight && this.naturalWidth > 800) {
expectWidth = 800;
expectHeight = expectWidth * this.naturalHeight / this.naturalWidth;
} else if (this.naturalHeight > this.naturalWidth && this.naturalHeight > 1200) {
expectHeight = 1200;
expectWidth = expectHeight * this.naturalWidth / this.naturalHeight;
}
var canvas = document.createElement("canvas");
var ctx = canvas.getContext("2d");
canvas.width = expectWidth;
canvas.height = expectHeight;
ctx.drawImage(this, 0, 0, expectWidth, expectHeight);
var base64 = null;
//修复ios上传图片的时候 被旋转的问题
if(Orientation != "" && Orientation != 1){
switch(Orientation){
case 6://需要顺时针（向左）90度旋转
_this.rotateImg(this,'left',canvas);
break;
case 8://需要逆时针（向右）90度旋转
_this.rotateImg(this,'right',canvas);
break;
case 3://需要180度旋转
_this.rotateImg(this,'right',canvas);//转两次
_this.rotateImg(this,'right',canvas);
break;
}
}
base64 = canvas.toDataURL("image/jpeg", 0.8);
if(fileList[i].size / 1024000 > 1){
_this.imgScale(base64, 4)
}else{
_this.imgArr.push({"src": base64});
}
console.log(JSON.stringify(_this.imgArr));
};
};
oReader.readAsDataURL(fileList[i]);
}
}
},
"imgScale": function(imgUrl,quality){
let img = new Image();
let _this = this;
let canvas = document.createElement('canvas');
let cxt = canvas.getContext('2d');
img.src = imgUrl;
img.onload = function(){
//缩放后图片的宽高
let width = img.naturalWidth/quality;
let height = img.naturalHeight/quality;
canvas.width = width;
canvas.height = height;
cxt.drawImage(this, 0, 0, width, height);
_this.imgArr.push({"src": canvas.toDataURL('image/jpeg')});
}
},
"rotateImg":function (img, direction,canvas) {//图片旋转
var min_step = 0;
var max_step = 3;
if (img == null)return;
var height = img.height;
var width = img.width;
var step = 2;
if (step == null) {
step = min_step;
}
if (direction == 'right') {
step++;
step > max_step && (step = min_step);
} else {
step--;
step < min_step && (step = max_step);
}
var degree = step * 90 * Math.PI / 180;
var ctx = canvas.getContext('2d');
switch (step) {
case 0:
canvas.width = width;
canvas.height = height;
ctx.drawImage(img, 0, 0);
break;
case 1:
canvas.width = height;
canvas.height = width;
ctx.rotate(degree);
ctx.drawImage(img, 0, -height);
break;
case 2:
canvas.width = width;
canvas.height = height;
ctx.rotate(degree);
ctx.drawImage(img, -width, -height);
break;
case 3:
canvas.width = height;
canvas.height = width;
ctx.rotate(degree);
ctx.drawImage(img, -width, 0);
break;
}
}
}
}
</script>
2.使用方法
<template>
<div>
<div class="album-img-list">
<ul>
<li v-for="img in imgList"><div class="album-bg-img"><img :src='img.src'> </div></li>
</ul>
</div>
<div class="album">
<label for="img-upload">上传照片</label>
<image-html5-upload :img-arr.sync="imgList"></image-html5-upload>
</div>
</div>
</template>