96 lines
2.7 KiB
JavaScript
96 lines
2.7 KiB
JavaScript
/*
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* @Author: zhang peng
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* @Date: 2021-08-03 10:57:51
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* @LastEditTime: 2021-08-16 17:25:43
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* @LastEditors: zhang peng
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* @Description:
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* @FilePath: \miniprogram-to-uniapp2\src\project\template\polyfill\base64Binary.js
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*
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* 借鉴自：https://github.com/dankogai/js-base64/blob/main/base64.js
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* 因uniapp没有window，也无法使用Buffer，因此直接使用polyfill
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*
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*/
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const b64ch = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/='
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const b64chs = [...b64ch]
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const b64re = /^(?:[A-Za-z\d+\/]{4})*?(?:[A-Za-z\d+\/]{2}(?:==)?|[A-Za-z\d+\/]{3}=?)?$/
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const b64tab = ((a) => {
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let tab = {}
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a.forEach((c, i) => tab[c] = i)
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return tab
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})(b64chs)
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const _fromCC = String.fromCharCode.bind(String)
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/**
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* polyfill version of `btoa`
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*/
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const btoaPolyfill = (bin) => {
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// console.log('polyfilled');
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let u32, c0, c1, c2, asc = ''
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const pad = bin.length % 3
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for (let i = 0;i < bin.length;) {
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if ((c0 = bin.charCodeAt(i++)) > 255 ||
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(c1 = bin.charCodeAt(i++)) > 255 ||
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(c2 = bin.charCodeAt(i++)) > 255)
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throw new TypeError('invalid character found')
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u32 = (c0 << 16) | (c1 << 8) | c2
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asc += b64chs[u32 >> 18 & 63]
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+ b64chs[u32 >> 12 & 63]
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+ b64chs[u32 >> 6 & 63]
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+ b64chs[u32 & 63]
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}
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return pad ? asc.slice(0, pad - 3) + "===".substring(pad) : asc
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}
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/**
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* polyfill version of `atob`
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*/
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const atobPolyfill = (asc) => {
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// console.log('polyfilled');
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asc = asc.replace(/\s+/g, '')
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if (!b64re.test(asc))
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throw new TypeError('malformed base64.')
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asc += '=='.slice(2 - (asc.length & 3))
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let u24, bin = '', r1, r2
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for (let i = 0;i < asc.length;) {
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u24 = b64tab[asc.charAt(i++)] << 18
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| b64tab[asc.charAt(i++)] << 12
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| (r1 = b64tab[asc.charAt(i++)]) << 6
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| (r2 = b64tab[asc.charAt(i++)])
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bin += r1 === 64 ? _fromCC(u24 >> 16 & 255)
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: r2 === 64 ? _fromCC(u24 >> 16 & 255, u24 >> 8 & 255)
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: _fromCC(u24 >> 16 & 255, u24 >> 8 & 255, u24 & 255)
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}
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return bin
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}
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/**
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* base64转ArrayBuffer
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*/
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function base64ToArrayBuffer (base64) {
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const binaryStr = atobPolyfill(base64)
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const byteLength = binaryStr.length
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const bytes = new Uint8Array(byteLength)
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for (let i = 0;i < byteLength;i++) {
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bytes[i] = binary.charCodeAt(i)
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}
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return bytes.buffer
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}
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/**
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* ArrayBuffer转base64
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*/
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function arrayBufferToBase64 (buffer) {
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let binaryStr = ""
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const bytes = new Uint8Array(buffer)
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var len = bytes.byteLength
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for (let i = 0;i < len;i++) {
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binaryStr += String.fromCharCode(bytes[i])
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}
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return btoaPolyfill(binaryStr)
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}
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module.exports = {
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base64ToArrayBuffer,
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arrayBufferToBase64,
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}
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