1.在index.html中引入mobileBUGFix.min.js
// mobileBUGFix.min.js内容见最下面附件2.在build/webpack.base.conf.js文件中增加：
module.exports = {
externals: {
'MegaPixImage': 'MegaPixImage',
'JPEGEncoder': 'JPEGEncoder'
}
}3.新建compressImage.js，内容如下：
import MegaPixImage from 'MegaPixImage' import JPEGEncoder from 'JPEGEncoder' // 将base64转换为blob export function convertBase64UrlToBlob(urlData) { var arr = urlData.split(',') var mime = arr[0].match(/:(.*?);/)[1] var bstr = atob(arr[1]) var n = bstr.length var u8arr = new Uint8Array(n) while (n--) { u8arr[n] = bstr.charCodeAt(n) } return new Blob([u8arr], { type: mime }) } // 压缩图片 export function compressImage(path, config) { return new Promise((resolve, reject) => { // 生成canvas var canvas = document.createElement('canvas') var ctx = canvas.getContext('2d') var img = new Image() img.crossOrigin = 'Anonymous' img.onload = function() { var that = this var w = that.width var h = that.height var scale = w / h w = config.width || config.height * scale || w h = config.height || config.width / scale || h // 最大宽高如有限制时的处理 w = config.maxWidth && w > config.maxWidth ? config.maxWidth : w h = config.maxHeight && h > config.maxHeight ? config.maxHeight : h w = Math.min(w, h * scale) || w h = Math.min(h, w / scale) || h var quality = 0.7 // 默认图片质量为0.7 // 创建属性节点 var anw = document.createAttribute('width') anw.nodeValue = w var anh = document.createAttribute('height') anh.nodeValue = h canvas.setAttributeNode(anw) canvas.setAttributeNode(anh) ctx.drawImage(that, 0, 0, w, h) if (config.quality && config.quality <= 1 && config.quality > 0) { quality = config.quality } var base64 = canvas.toDataURL('image/jpeg', quality) // 在指定图片格式为 image/jpeg 或 image/webp的情况下，可以从 0 到 1 的区间内选择图片的质量。如果超出取值范围，将会使用默认值 0.92。其他参数会被忽略。 // 修复IOS if (navigator.userAgent.match(/iphone/i)) { var mpImg = new MegaPixImage(img) mpImg.render(canvas, { maxWidth: w, maxHeight: h, quality: quality }) base64 = canvas.toDataURL('image/jpeg', quality) } // 修复android if (navigator.userAgent.match(/Android/i)) { var encoder = new JPEGEncoder() base64 = encoder.encode(ctx.getImageData(0, 0, w, h), quality * 100) } // var blob = convertBase64UrlToBlob(base64) // 回调函数返回base64的值，也可根据自己的需求返回blob的值 // base64 = base64.substr(base64.indexOf(',') + 1) // 去掉base64前面的部分 resolve(base64) canvas = null } img.src = path }) }
4.使用
// 引入 import { compressImage } from './compressImage' // 具体路径按自己存放的位置而定 // 调用 compressImage(图片路径, { maxWidth: 1920, // 限制最大宽度 maxHeight: 1080, // 限制最大高度，若宽高都限制了，按原图比例最小边为主 width: 100, // 压缩后图片的宽 height: 200, // 压缩后图片的高，宽高若只传一个，则按图片原比例进行压缩 quality: 0.8 // 压缩后图片的清晰度，取值0-1，值越小，所绘制出的图像越模糊 }).then(result => { console.log(result) // result即为压缩后的结果 })
附件：
mobileBUGFix.min.js
/* jpeg_encoder_basic.js for android jpeg压缩质量修复 */
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/* megapix-image.js for IOS(iphone5+) drawImage画面扭曲修复 */
!function(){function a(a){var d,e,b=a.naturalWidth,c=a.naturalHeight;return b*c>1048576?(d=document.createElement("canvas"),d.width=d.height=1,e=d.getContext("2d"),e.drawImage(a,-b+1,0),0===e.getImageData(0,0,1,1).data[3]):!1}function b(a,b,c){var e,f,g,h,i,j,k,d=document.createElement("canvas");for(d.width=1,d.height=c,e=d.getContext("2d"),e.drawImage(a,0,0),f=e.getImageData(0,0,1,c).data,g=0,h=c,i=c;i>g;)j=f[4*(i-1)+3],0===j?h=i:g=i,i=h+g>>1;return k=i/c,0===k?1:k}function c(a,b,c){var e=document.createElement("canvas");return d(a,e,b,c),e.toDataURL("image/jpeg",b.quality||.8)}function d(c,d,f,g){var m,n,o,p,q,r,s,t,u,v,w,h=c.naturalWidth,i=c.naturalHeight,j=f.width,k=f.height,l=d.getContext("2d");for(l.save(),e(d,l,j,k,f.orientation),m=a(c),m&&(h/=2,i/=2),n=1024,o=document.createElement("canvas"),o.width=o.height=n,p=o.getContext("2d"),q=g?b(c,h,i):1,r=Math.ceil(n*j/h),s=Math.ceil(n*k/i/q),t=0,u=0;i>t;){for(v=0,w=0;h>v;)p.clearRect(0,0,n,n),p.drawImage(c,-v,-t),l.drawImage(o,0,0,n,n,w,u,r,s),v+=n,w+=r;t+=n,u+=s}l.restore(),o=p=null}function e(a,b,c,d,e){switch(e){case 5:case 6:case 7:case 8:a.width=d,a.height=c;break;default:a.width=c,a.height=d}switch(e){case 2:b.translate(c,0),b.scale(-1,1);break;case 3:b.translate(c,d),b.rotate(Math.PI);break;case 4:b.translate(0,d),b.scale(1,-1);break;case 5:b.rotate(.5*Math.PI),b.scale(1,-1);break;case 6:b.rotate(.5*Math.PI),b.translate(0,-d);break;case 7:b.rotate(.5*Math.PI),b.translate(c,-d),b.scale(-1,1);break;case 8:b.rotate(-.5*Math.PI),b.translate(-c,0)}}function f(a){var b,c,d;if(window.Blob&&a instanceof Blob){if(b=new Image,c=window.URL&&window.URL.createObjectURL?window.URL:window.webkitURL&&window.webkitURL.createObjectURL?window.webkitURL:null,!c)throw Error("No createObjectURL function found to create blob url");b.src=c.createObjectURL(a),this.blob=a,a=b}a.naturalWidth||a.naturalHeight||(d=this,a.onload=function(){var b,c,a=d.imageLoadListeners;if(a)for(d.imageLoadListeners=null,b=0,c=a.length;c>b;b++)a[b]()},this.imageLoadListeners=[]),this.srcImage=a}f.prototype.render=function(a,b,e){var f,g,h,i,j,k,l,m,n,o,p;if(this.imageLoadListeners)return f=this,this.imageLoadListeners.push(function(){f.render(a,b,e)}),void 0;b=b||{},g=this.srcImage.naturalWidth,h=this.srcImage.naturalHeight,i=b.width,j=b.height,k=b.maxWidth,l=b.maxHeight,m=!this.blob||"image/jpeg"===this.blob.type,i&&!j?j=h*i/g<<0:j&&!i?i=g*j/h<<0:(i=g,j=h),k&&i>k&&(i=k,j=h*i/g<<0),l&&j>l&&(j=l,i=g*j/h<<0),n={width:i,height:j};for(o in b)n[o]=b[o];p=a.tagName.toLowerCase(),"img"===p?a.src=c(this.srcImage,n,m):"canvas"===p&&d(this.srcImage,a,n,m),"function"==typeof this.onrender&&this.onrender(a),e&&e()},"function"==typeof define&&define.amd?define([],function(){return f}):this.MegaPixImage=f}();
原文地址：https://www.cnblogs.com/shifeng-/p/11168933.html
时间： 2024-10-10 17:43:52