ios拍照上傳問題，目前這個項目是因為ios拍照上傳圖片過大，故此前端需要在上傳的時候壓縮圖片
上傳圖片壓縮是參考博客園一位大佬的代碼
安裝 npm install exif-js --save
<template>
<div>
<div v-for="(item,index) in ImgList">
<img src="../../../static/img/d.png" alt="" class="del" @click="del(index)" />
<img :src="$store.state.website.website_domain_name + '/uploads/' + item" alt="" />
</div>
<form enctype="multipart/form-data" method="post" id="upload">
<img src="../../../static/img/jh.png" alt="" class="tp" />
<input v-if="type==1" type="file" name="upload" capture="camera" accept="image/*" @change="upload($event)" class="upload1" style="width: 100%; height: 100%; opacity: 0;position: absolute;top: 0;left: 0;">
</form>
</div>
</template>
export default {
data () {
return {
ImgList:'',
picValue:''
}
},
mounted () {
},
methods: {
upload (e) {
let files = e.target.files || e.dataTransfer.files;
if (!files.length) return;
this.picValue = files[0];
this.imgPreview(this.picValue);
},
imgPreview (file) {
let self = this;
let Orientation;
//去獲取拍照時的信息，解決拍出來的照片旋轉問題
Exif.getData(file, function(){
Orientation = Exif.getTag(this, 'Orientation');
});
// 看支持不支持FileReader
if (!file || !window.FileReader) return;
if (/^image/.test(file.type)) {
// 創建一個reader
let reader = new FileReader();
// 將圖片2將轉成 base64 格式
reader.readAsDataURL(file);
// 讀取成功后的回調
reader.onloadend = function () {
let result = this.result;
let img = new Image();
img.src = result;
//判斷圖片是否大於100K,是就直接上傳，反之壓縮圖片
if (this.result.length <= (100 * 1024)) {
self.headerImage = this.result;
self.postImg(self.headerImage);
}else {
img.onload = function () {
let data = self.compress(img,Orientation);
self.headerImage = data;
self.postImg(self.headerImage);
}
}
}
}
},
postImg () {
//這里寫接口
var _this = this;
let param = new FormData() // 創建form對象
param.append('img', headerImage)
let config = {
headers: {
'Content-Type': 'multipart/form-data'
}
}
_this.$store.commit('loadingOFFON', true)
_this.isshow = false
_this.$http.post(_this.$store.state.url + '/index/uploadImgs', param, config).then(function(res) {
if (!res) return
_this.src = res.imgurl;
_this.ImgList.push(res.imgurl)
})
},
rotateImg (img, direction,canvas) {
//最小與最大旋轉方向，圖片旋轉4次后回到原方向
const min_step = 0;
const max_step = 3;
if (img == null)return;
//img的高度和寬度不能在img元素隱藏后獲取，否則會出錯
let height = img.height;
let width = img.width;
let step = 2;
if (step == null) {
step = min_step;
}
if (direction == 'right') {
step++;
//旋轉到原位置，即超過最大值
step > max_step && (step = min_step);
} else {
step--;
step < min_step && (step = max_step);
}
//旋轉角度以弧度值為參數
let degree = step * 90 * Math.PI / 180;
let 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;
}
},
compress(img,Orientation) {
let canvas = document.createElement("canvas");
let ctx = canvas.getContext('2d');
//瓦片canvas
let tCanvas = document.createElement("canvas");
let tctx = tCanvas.getContext("2d");
let initSize = img.src.length;
let width = img.width;
let height = img.height;
//如果圖片大於四百萬像素，計算壓縮比並將大小壓至400萬以下
let ratio;
if ((ratio = width * height / 4000000) > 1) {
console.log("大於400萬像素")
ratio = Math.sqrt(ratio);
width /= ratio;
height /= ratio;
} else {
ratio = 1;
}
canvas.width = width;
canvas.height = height;
// 鋪底色
ctx.fillStyle = "#fff";
ctx.fillRect(0, 0, canvas.width, canvas.height);
//如果圖片像素大於100萬則使用瓦片繪制
let count;
if ((count = width * height / 1000000) > 1) {
console.log("超過100W像素");
count = ~~(Math.sqrt(count) + 1); //計算要分成多少塊瓦片
// 計算每塊瓦片的寬和高
let nw = ~~(width / count);
let nh = ~~(height / count);
tCanvas.width = nw;
tCanvas.height = nh;
for (let i = 0; i < count; i++) {
for (let j = 0; j < count; j++) {
tctx.drawImage(img, i * nw * ratio, j * nh * ratio, nw * ratio, nh * ratio, 0, 0, nw, nh);
ctx.drawImage(tCanvas, i * nw, j * nh, nw, nh);
}
}
} else {
ctx.drawImage(img, 0, 0, width, height);
}
//修復ios上傳圖片的時候 被旋轉的問題
if(Orientation != "" && Orientation != 1){
switch(Orientation){
case 6://需要順時針（向左）90度旋轉
this.rotateImg(img,'left',canvas);
break;
case 8://需要逆時針（向右）90度旋轉
this.rotateImg(img,'right',canvas);
break;
case 3://需要180度旋轉
this.rotateImg(img,'right',canvas);//轉兩次
this.rotateImg(img,'right',canvas);
break;
}
}
//進行最小壓縮
let ndata = canvas.toDataURL('image/jpeg', 0.1);
console.log('壓縮前：' + initSize);
console.log('壓縮后：' + ndata.length);
console.log('壓縮率：' + ~~(100 * (initSize - ndata.length) / initSize) + "%");
tCanvas.width = tCanvas.height = canvas.width = canvas.height = 0;
return ndata;
},
}
}
</script>