<template> <div> <input type="file" id="upload" accept="image" @change="upload" /> </div> </template> <script> export default { data() { return { picValue:{}, headerImage:'' }; }, components: {}, methods: { upload(e) { console.log(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; //去获取拍照时的信息，解决拍出来的照片旋转问题 self.Exif.getData(file, function() { Orientation = self.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100K,是就直接上传，反之压缩图片 if (this.result.length <= 100 * 1024) { self.headerImage = this.result; self.postImg(); } else { img.onload = function() { let data = self.compress(img, Orientation); self.headerImage = data; self.postImg(); }; } }; } }, 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', 0.1); tCanvas.width = tCanvas.height = canvas.width = canvas.height = 0; return ndata; }, 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; } }, postImg() { //这里写接口
//打印的图片base64
console.log('this.headerImage',this.headerImage); //接口 axios } } }; </script>
要先运行npm install exif-js --save
然后在main.js中添加
import Exif from 'exif-js'
Vue.use(Exif)
Vue.prototype.Exif = Exif