data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAABGU....
报错是因为没有去除 data:image/png;base64,应只要后面的文件流
1. base64 : 可以直接当作链接地址使用
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data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAABGU....
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2. File 对象:
File{ lastModified: 1649490762164 lastModifiedDate: Sat Apr 09 2022 15:52:42 GMT+0800 (GMT+08:00) {} name: "1649490762160-251.png" size: 25748 type: "image/png" webkitRelativePath: "" [[Prototype]]: File }
3. Blob 对象
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Blob{
size: 25748
type: "image/png"
[[Prototype]]: Blob
}
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除了base64 可以直接当作链接使用,File 对象和Bolb 对象也可以通过转换 成base64 直接使用,或者使用
window.URL.createObjectURL(File 对象或者Bolb 对象) 直接生成链接 : 类似:blob:null/22ec44b8-5864-4960-8ea8-a71a7e40bb63 所以:能直接当作链接是使用在这三者关系中有1 2 |
1. data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAABGU....
2. blob: null /22ec44b8-5864-4960-8ea8-a71a7e40bb63
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一:base64 转 Blob 对象
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//base64 转 Blob对象
/* base64: data:image/png;base64,iVB....
/* Blob:{...}
*/
function base64ToBlob(data) {
var arr = data.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 Blob([u8arr], { type: mime });
}
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二: base64 转 File 对象
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/** base64 转 File 对象
/* @param data base64
/* @param filename 自定义文件名
/* @return File 对象
*/
function base64ToFile(data, filename) {
var arr = data.split( ',' ), mime = arr[0].match(/:(.*?);/)[1],
bstr = atob(arr[1]), n = bstr.length, u8arr = new Uint8Array(n);
let suffixArr = mime.split( "/" )
if (suffixArr.length && !filename) {
let suffix = suffixArr[suffixArr.length - 1]
filename = new Date().getTime() + "-" + Math.floor((Math.random() * 10000)) + "." + suffix
}
while (n--) {
u8arr[n] = bstr.charCodeAt(n);
}
return new File([u8arr], filename, { type: mime });
}
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三: File 对象,Blob 对象 转base64
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//blob ,File 对象 转 base64
function blobFileTobase64(blobFile) {
let reader = new FileReader()
reader.readAsDataURL(blobFile);
return new Promise((resolve, reject) => {
reader.onload = function () {
resolve( this .result)
}
reader.onerror = (err) => {
reject(err);
};
})
}
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四: blob链接转 base64 :利用canvas.toDataURL的API转化成base64
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blob: null /22ec44b8-5864-4960-8ea8-a71a7e40bb63 转为
data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAABGU....
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function urlToBase64(url, type = "image/png" ) {
return new Promise((resolve, reject) => {
let img = new Image()
img.src = url
img.onload = function () {
let canvas = document.createElement( "canvas" )
canvas.width = this .naturalWidth
canvas.height = this .naturalHeight
let ctx = canvas.getContext( "2d" )
ctx.drawImage(img, 0, 0)
let result = canvas.toDataURL(type || 'image/png' )
resolve(result)
}
img.onerror = function (err) {
reject(err)
}
})
}
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五: 压缩图片:接收一个File/Blob 对象,返回的是一个base64
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/*
blobFile:file/blob 对象
option:{type:"image/jpeg",width:'',height:"",quality:0.92,scale:1}
*/
function compressImg(blobFile, option = {}) {
return new Promise((resolve, reject) => {
let reader = new FileReader()
reader.onload = function () {
let img = new Image()
img.src = this .result
img.onload = function () {
console.log( "原图片大小:" , this .src.length); //这是base64 ,所以可以指定图片大小
let imgSize = this .src.length;
let targetSize = 100 * 1024;
if (imgSize <= targetSize) {
return resolve( this .src)
}
let canvas = document.createElement( "canvas" )
let ctx = canvas.getContext( "2d" )
//原图尺寸
let imgW = this .naturalWidth
let imgH = this .naturalHeight
//新图比例大小
let scale = option.scale || 1;
let ratio = imgW / imgH; //宽高比例
let targetW = option.width || imgW * scale
let targetH = option.height || imgH * scale
canvas.width = targetW
canvas.height = targetH
ctx.drawImage(img, 0, 0, targetW, targetH)
let fileType = blobFile.type || option.type || 'image/jpeg'
let quality = option.quality || 0.5
let result = canvas.toDataURL(fileType, quality)
console.log( "压缩后:" , result.length)
resolve(result)
}
}
reader.onerror = function () {
reject( new Error(`${blobFile} must is Blob or File 对象`))
}
reader.readAsDataURL(blobFile)
})
}
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