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 */
function JPEGEncoder(a){function I(a){var c,i,j,k,l,m,n,o,p,b=[16,11,10,16,24,40,51,61,12,12,14,19,26,58,60,55,14,13,16,24,40,57,69,56,14,17,22,29,51,87,80,62,18,22,37,56,68,109,103,77,24,35,55,64,81,104,113,92,49,64,78,87,103,121,120,101,72,92,95,98,112,100,103,99];for(c=0;64>c;c++)i=d((b[c]*a+50)/100),1>i?i=1:i>255&&(i=255),e[z[c]]=i;for(j=[17,18,24,47,99,99,99,99,18,21,26,66,99,99,99,99,24,26,56,99,99,99,99,99,47,66,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99],k=0;64>k;k++)l=d((j[k]*a+50)/100),1>l?l=1:l>255&&(l=255),f[z[k]]=l;for(m=[1,1.387039845,1.306562965,1.175875602,1,.785694958,.5411961,.275899379],n=0,o=0;8>o;o++)for(p=0;8>p;p++)g[n]=1/(8*e[z[n]]*m[o]*m[p]),h[n]=1/(8*f[z[n]]*m[o]*m[p]),n++}function J(a,b){var f,g,c=0,d=0,e=new Array;for(f=1;16>=f;f++){for(g=1;g<=a[f];g++)e[b[d]]=[],e[b[d]][0]=c,e[b[d]][1]=f,d++,c++;c*=2}return e}function K(){i=J(A,B),j=J(E,F),k=J(C,D),l=J(G,H)}function L(){var c,d,e,a=1,b=2;for(c=1;15>=c;c++){for(d=a;b>d;d++)n[32767+d]=c,m[32767+d]=[],m[32767+d][1]=c,m[32767+d][0]=d;for(e=-(b-1);-a>=e;e++)n[32767+e]=c,m[32767+e]=[],m[32767+e][1]=c,m[32767+e][0]=b-1+e;a<<=1,b<<=1}}function M(){for(var a=0;256>a;a++)x[a]=19595*a,x[a+256>>0]=38470*a,x[a+512>>0]=7471*a+32768,x[a+768>>0]=-11059*a,x[a+1024>>0]=-21709*a,x[a+1280>>0]=32768*a+8421375,x[a+1536>>0]=-27439*a,x[a+1792>>0]=-5329*a}function N(a){for(var b=a[0],c=a[1]-1;c>=0;)b&1<<c&&(r|=1<<s),c--,s--,0>s&&(255==r?(O(255),O(0)):O(r),s=7,r=0)}function O(a){q.push(w[a])}function P(a){O(255&a>>8),O(255&a)}function Q(a,b){var c,d,e,f,g,h,i,j,l,p,q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z,$,_,k=0;const 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c.width=b.width,c.height=b.height,d=c.getContext("2d"),d.drawImage(b,0,0),d.getImageData(0,0,c.width,c.height)}

/* 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}();

转载于:https://www.cnblogs.com/shifeng-/p/11168933.html

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