<template>
<van-uploader :after-read="afterRead" v-show='is_img' />
</template>
npm install exif-js --save 安装
import Exif from 'exif-js'
data() {
return {
// 图片信息
files: {
name: "",
type: ""
},
}
},
// 上传图片
afterRead(file) {
this.files.name = file.file.name // 获取文件名
this.files.type = file.file.type // 获取类型
this.imgPreview(file.file)
},
// 处理图片
imgPreview(file) {
let self = this
let Orientation
//去获取拍照时的信息，解决拍出来的照片旋转问题 npm install exif-js --save 这里需要安装一下包
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)) {
// 创建一个reader
let reader = new FileReader()
// 将图片2将转成 base64 格式
reader.readAsDataURL(file)
// 读取成功后的回调
reader.onloadend = function() {
let result = this.result
let img = new Image()
img.src = result
//判断图片是否大于500K,是就直接上传，反之压缩图片
if (this.result.length <= 500 * 1024) {
// 上传图片
self.postImg(this.result);
} else {
img.onload = function() {
let data = self.compress(img, Orientation)
// 上传图片
self.postImg(data);
}
}
}
}
},
// 压缩图片
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
//如果图片大于四百万像素，计算压缩比并将大小压至400万以下
let ratio
if ((ratio = (width * height) / 4000000) > 1) {
// console.log("大于400万像素");
ratio = Math.sqrt(ratio)
width /= ratio
height /= ratio
} else {
ratio = 1
}
canvas.width = width
canvas.height = height
// 铺底色
ctx.fillStyle = '#fff'
ctx.fillRect(0, 0, canvas.width, canvas.height)
//如果图片像素大于100万则使用瓦片绘制
let count
if ((count = (width * height) / 1000000) > 1) {
// console.log("超过100W像素");
count = ~~(Math.sqrt(count) + 1) //计算要分成多少块瓦片
// 计算每块瓦片的宽和高
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(img, 'left', canvas)
break
case 8: //需要逆时针（向右）90度旋转
this.rotateImg(img, 'right', canvas)
break
case 3: //需要180度旋转
this.rotateImg(img, 'right', canvas) //转两次
this.rotateImg(img, 'right', canvas)
break
}
}
//进行最小压缩
let ndata = canvas.toDataURL('image/jpeg', 0.2)
tCanvas.width = tCanvas.height = canvas.width = canvas.height = 0;
console.log(ndata)
return ndata
},
// 旋转图片
rotateImg(img, direction, canvas) {
//最小与最大旋转方向，图片旋转4次后回到原方向
const min_step = 0
const max_step = 3
if (img == null) return
//img的高度和宽度不能在img元素隐藏后获取，否则会出错
let height = img.height
let width = img.width
let step = 2
if (step == null) {
step = min_step
}
if (direction == 'right') {
step++
//旋转到原位置，即超过最大值
step > max_step && (step = min_step)
} else {
step--
step < min_step && (step = max_step)
}
//旋转角度以弧度值为参数
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
}
},
//将base64转换为文件
dataURLtoFile(dataurl) {
var arr = dataurl.split(','),
bstr = atob(arr[1]),
n = bstr.length,
u8arr = new Uint8Array(n)
while (n--) {
u8arr[n] = bstr.charCodeAt(n)
}
return new File([u8arr], this.files.name, {
type: this.files.type
})
},
// 提交图片到后端
postImg(base64) {
let file = this.dataURLtoFile(base64)
let formData = new window.FormData()
formData.append('file', file)
// 提交图片
let config = {
headers: {
"Content-Type": "multipart/form-data"
}
};
this.$axios.post("https://mail.xxxxxxx.com/shop/file/uploadimg", formData, config)
.then((res) => {
// console.log(res.data.msg);
this.img = res.data.msg
this.fs()
})
// Some code
},
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