没什么文字直接上代码
//这是一个解决exif更改脱方向的一个js文件
// 应用前先npm install exif-js --save或者直接引入exif-js
//// 调用方法
// let baseData;
// imgExif(file,function (base){
// baseData=base
// });
import Exif from 'exif-js' //引入exif
let u = {};
// 转换的主体方法
u.index = (file, callback) => {
let Orientation, resultData; //图片的方向,返回的值
//去获取拍照时的信息,解决拍出来的照片旋转问题
Exif.getData(file, function () {
Orientation = Exif.getTag(this, 'Orientation');
});
// 看支持不支持FileReader
if (!file || !window.FileReader) return;
// 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;
//判断图片是否有方向值没有直接返回base64
if (!Orientation) {
callback(result);
} else {
let img = new Image();
img.src = result;
//图片信息加载完转换方向
img.onload = function () {
resultData = u.compress(img, Orientation);
callback(resultData);
}
}
}
}
};
//更改旋转方向
u.compress = (img, Orientation) => {
let canvas = document.createElement("canvas"), ctx = canvas.getContext('2d'),
tCanvas = document.createElement("canvas"), tctx = tCanvas.getContext("2d"), initSize = img.src.length,
width = img.width, height = img.height, ratio = 1; //声明
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
u.rotateImg(img, 'left', canvas);
break;
case 8://需要逆时针(向右)90度旋转
u.rotateImg(img, 'right', canvas);
break;
case 3://需要180度旋转
u.rotateImg(img, 'right', canvas, 2);//转两次
break;
}
}
//进行最小压缩
let ndata = canvas.toDataURL('image/jpeg', 1);
tCanvas.width = tCanvas.height = canvas.width = canvas.height = 0;
return ndata;
};
//更改旋转方向
u.rotateImg = (img, direction, canvas, num) => {
//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180度
step = num ? num : 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;
}
};
window.imgExif = u;
要是后台需要的是file用这个转换一下就可以了
//将base64转换为img文件
u.compress = (img, Orientation) => {
let arr = dataurl.split(','),
mime = arr[0].match(/:(.*?);/)[1],
bstr = atob(arr[1]),
n = bstr.length,
u8arr = new Uint8Array(n);
while (n--) {
u8arr[n] = bstr.charCodeAt(n);
}
return new File([u8arr], filename, {type: mime});
};