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vue头像上传与文件压缩

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08/23
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工作中遇到的问题记录：vue开发头像上传组件，后端提供接口，需求为可相册上传，可相机拍摄上传，文件大小限制为2M

需求点分析

  1. 移动端调用相册/摄像头实现拍照
  2. 图片压缩，当前高像素的相机拍出来的图片都有个4-5m大小，超出了限定的2m
  3. 图片上传

第一点：移动端调用相册/摄像头实现拍照

这就比较简单了，H5的标签足已经能满足我们的要求了，我们要做的只是让它更美观一点

<div class="yb-headSet-but">
<div class="btn-box">
<input type="file" accept="image/*" @change="uploadImg" class="fromAlbum"> //设置input opacity为0，定位覆盖a标签，a标签设置为设计稿的按钮样式
<a href="" class="weui-but">从相册选一张</a>
</div>
<div class="btn-box">
<a href="" class="weui-but">拍一张照片</a>
<input type="file" accept="image/*" @change="uploadImg" capture="camera" class="fromCamera"> //两者区别：capture="camera" 可直接调用摄像头
</div>
</div>

第二点：图片压缩

利用的是canvas的drawImage 和 toDataURL的api，具体代码是复制的 https://www.jianshu.com/p/4587312d2f44

修改了几个大佬笔误的地方

imgResize(file, callback) {
var _this = this;
var fileReader = new FileReader();
fileReader.onload = function() {
var IMG = new Image();
IMG.src = this.result;
IMG.onload = function() {
var w = this.naturalWidth,
h = this.naturalHeight,
resizeW = 0,
resizeH = 0;
// maxSize 是压缩的设置，设置图片的最大宽度和最大高度，等比缩放，level是报错的质量，数值越小质量越低
var maxSize = {
width: 500,
height: 500,
level: 0.6
};
if (w > maxSize.width || h > maxSize.height) {
var multiple = Math.max(w / maxSize.width, h / maxSize.height);
resizeW = w / multiple;
resizeH = h / multiple;
} else {
// 如果图片尺寸小于最大限制，则不压缩直接上传
return callback(file);
}
var canvas = document.createElement("canvas");
var ctx = canvas.getContext("2d");
if (window.navigator.userAgent.indexOf("iPhone") > 0) {
canvas.width = resizeH;
canvas.height = resizeW;
ctx.rotate(90 * Math.PI / 180);
ctx.drawImage(IMG, 0, -resizeH, resizeW, resizeH);
} else {
canvas.width = resizeW;
canvas.height = resizeH;
ctx.drawImage(IMG, 0, 0, resizeW, resizeH);
}
var base64 = canvas.toDataURL("image/" + _this.fileType, maxSize.level);
_this.convertBlob(window.atob(base64.split(",")[1]), callback);
};
};
fileReader.readAsDataURL(file);
},

图片上传

使用canvas.toDataURL获得的是base64格式，上传时需要转换成Blob二进制格式，使用formData提交

//Blob对象生成
convertBlob(base64, callback) {
var buffer = new ArrayBuffer(base64.length);
var ubuffer = new Uint8Array(buffer);
for (var i = 0; i < base64.length; i++) {
ubuffer[i] = base64.charCodeAt(i);
}
var blob;
try {
blob = new Blob([buffer], { type: "image/" + this.fileType });
} catch (e) {
window.BlobBuilder =
window.BlobBuilder ||
window.WebKitBlobBuilder ||
window.MozBlobBuilder ||
window.MSBlobBuilder;
if (e.name === "TypeError" && window.BlobBuilder) {
var blobBuilder = new BlobBuilder();
blobBuilder.append(buffer);
blob = blobBuilder.getBlob("image/" + this.fileType);
}
}
callback(blob);
},
//提交函数
postImg(file) {
let image = new FormData();
image.append("file", file, this.random_string(12) + '.' + this.fileType);
console.log(image);
setHead(image).then(res => {
this.$indicator.close();
if (res.Success) {
let newPath = res.photoPath +'?t=' + this.random_string(12);
this.$store.commit("UPDATE_BASEINFO", { photoPath: newPath });
this.picValue = newPath;
this.$messagebox.alert(res.Message);
} else {
this.$messagebox.alert(res.Message);
}
});
},

注意注意 这里有个巨大的坑。。。。。

这个坑是这样的，我使用压缩过的Blob格式提交后台时，返回提示文件格式不正确，不属于jpeg、jpg等，这我就纳闷了，我上传的formData里面写明了文件格式了啊；

后来经过简书大佬 一斤代码 老大的帮助，老大测试后说出了问题所在：那就是 FormData.append('file', file),如果只有两个参数，（第三个参数是文件名）的情况下，默认fileName=“blob”，这样上次至后台，如果后台未做其他处理的话，就会出现报错的情况，后来就添加了随机文件名，完整代码如下

<template>
<div class="yb-page">
<div class="yb-page-inner">
<div class="yb-headSetting">
<div class="yb-headSet-img">
<img :src="picValue" alt="" onerror="this.src='https://ixxxxxx.com/we/tmpls/t9000/img/account/blackHead@2x.png'">
</div>
<div class="yb-headSet-but">
<div class="btn-box">
<input type="file" ref="avatarInput" accept="image/*" @change="uploadImg" class="fromAlbum">
<a href="" class="weui-but">从相册选一张</a>
</div>
<div class="btn-box">
<a href="" class="weui-but">拍一张照片</a>
<input type="file" accept="image/*" @change="uploadImg" capture="camera" class="fromCamera">
</div>
</div>
</div>
</div>
</div>
</template>
<script>
import { setHead } from "@/api/user";
export default {
data() {
return {
picValue: this.$store.getters.baseInfo.photoPath,
file: null,
fileType: ''
};
},
methods: {
uploadImg(e) {
if (e.target.value == "") {
return;
}
this.$indicator.open();
let files = e.target.files || e.dataTransfer.files;
if (!files.length) return;
this.file = files[0];
this.fileType = this.file.type.split('/')[1];
this.imgResize(files[0], this.postImg);
},
postImg(file) {
let image = new FormData();
image.append("file", file, this.random_string(12) + '.' + this.fileType);
console.log(image);
setHead(image).then(res => {
this.$indicator.close();
if (res.Success) {
let newPath = res.photoPath +'?t=' + this.random_string(12);
this.$store.commit("UPDATE_BASEINFO", { photoPath: newPath });
this.picValue = newPath;
this.$messagebox.alert(res.Message);
} else {
this.$messagebox.alert(res.Message);
}
});
},
imgResize(file, callback) {
var _this = this;
var fileReader = new FileReader();
fileReader.onload = function() {
var IMG = new Image();
IMG.src = this.result;
IMG.onload = function() {
var w = this.naturalWidth,
h = this.naturalHeight,
resizeW = 0,
resizeH = 0;
// maxSize 是压缩的设置，设置图片的最大宽度和最大高度，等比缩放，level是报错的质量，数值越小质量越低
var maxSize = {
width: 500,
height: 500,
level: 0.6
};
if (w > maxSize.width || h > maxSize.height) {
var multiple = Math.max(w / maxSize.width, h / maxSize.height);
resizeW = w / multiple;
resizeH = h / multiple;
} else {
// 如果图片尺寸小于最大限制，则不压缩直接上传
return callback(file);
}
var canvas = document.createElement("canvas");
var ctx = canvas.getContext("2d");
if (window.navigator.userAgent.indexOf("iPhone") > 0) {
canvas.width = resizeH;
canvas.height = resizeW;
ctx.rotate(90 * Math.PI / 180);
ctx.drawImage(IMG, 0, -resizeH, resizeW, resizeH);
} else {
canvas.width = resizeW;
canvas.height = resizeH;
ctx.drawImage(IMG, 0, 0, resizeW, resizeH);
}
var base64 = canvas.toDataURL("image/" + _this.fileType, maxSize.level);
_this.convertBlob(window.atob(base64.split(",")[1]), callback);
};
};
fileReader.readAsDataURL(file);
},
convertBlob(base64, callback) {
var buffer = new ArrayBuffer(base64.length);
var ubuffer = new Uint8Array(buffer);
for (var i = 0; i < base64.length; i++) {
ubuffer[i] = base64.charCodeAt(i);
}
var blob;
try {
blob = new Blob([buffer], { type: "image/" + this.fileType });
} catch (e) {
window.BlobBuilder =
window.BlobBuilder ||
window.WebKitBlobBuilder ||
window.MozBlobBuilder ||
window.MSBlobBuilder;
if (e.name === "TypeError" && window.BlobBuilder) {
var blobBuilder = new BlobBuilder();
blobBuilder.append(buffer);
blob = blobBuilder.getBlob("image/" + this.fileType);
}
}
callback(blob);
},
random_string(len) {
len = len || 32;
var chars = "ABCDEFGHJKMNPQRSTWXYZabcdefhijkmnprstwxyz2345678";
var maxPos = chars.length;
var pwd = "";
for (var i = 0; i < len; i++) {
pwd += chars.charAt(Math.floor(Math.random() * maxPos));
}
return pwd;
}
}
};
</script>