1.file表单组件监听change获取file文件
2.创建fileReader 获取base64位图片路由
3.实例一个Image 将base64位图片路由对其进行赋值，创建canvas 通过drawImage方法对其进行等比例缩放复制，实现图片压缩
4.引入 exif-js 模块 获取旋转角度信息，非1的，对canvas进行旋转，重绘，再通过toDataURL 获取旋转矫正后的图片64位
5.调用回调函数进行图片上传
//upload
import EXIF from "exif-js";
function 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
var min_step = 0;
var max_step = 3;
//var img = document.getElementById(pid);
if (img == null)return;
var height = canvas.height;
var width = canvas.width;
//var step = img.getAttribute(‘step‘);
var 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
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,width,height);
break;
case 1:
canvas.width = height;
canvas.height = width;
ctx.rotate(degree);
ctx.drawImage(img, 0, -height,width,height);
break;
case 2:
canvas.width = width;
canvas.height = height;
ctx.rotate(degree);
ctx.drawImage(img, -width, -height,width,height);
break;
case 3:
canvas.width = height;
canvas.height = width;
ctx.rotate(degree);
ctx.drawImage(img, -width, 0,width,height);
break;
}
}
export const upload=(file,callback)=>{//传入file文件
//对图片旋转处理
let Orientation = null;
//获取照片方向角属性，用户旋转控制
EXIF.getData(file, function() {
EXIF.getAllTags(this);
Orientation = EXIF.getTag(this, ‘Orientation‘);
});
let oReader = new FileReader();
oReader.onload = function(e) {
var image = new Image();
image.src = e.target.result;
debugger;
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;
if(Orientation != "" && Orientation != 1){
switch(Orientation){
case 6://需要顺时针（向左）90度旋转
// alert(‘需要顺时针（向左）90度旋转‘);
rotateImg(this,‘left‘,canvas);
break;
case 8://需要逆时针（向右）90度旋转
// alert(‘需要顺时针（向右）90度旋转‘);
rotateImg(this,‘right‘,canvas);
break;
case 3://需要180度旋转
// alert(‘需要180度旋转‘);
rotateImg(this,‘right‘,canvas);//转两次
rotateImg(this,‘right‘,canvas);
break;
}
}
base64 = canvas.toDataURL("image/jpeg", 0.8);
callback(base64)
};
};
oReader.readAsDataURL(file);
}
使用示例
<template>
<div class="hello">
<h1>exif 图片数码信息</h1>
<input type="file" name="pic" ref="file" accept="image/*" @change="uploadFile"/>
<div id="output">
<img :src="src" >
</div>
</div>
</template>
<script>
import {upload} from "../assets/tool/upload";
export default {
name: ‘exif‘,
data(){
return {
src:‘‘
}
},
methods:{
uploadFile(e){
//获取file文件
let files=e.target.files || e.dataTransfer.files;
if(files.length<=0)
return;
let file=files[0];
let vm=this;
upload(file,function(base64){vm.src=base64})
},
},
mounted() {
}
}
</script>