BeadQR/miniprogram/utils/qrcore/byte-data.js

const Mode = require('./mode')

// 微信部分真机运行时没有 TextEncoder。二维码 BYTE 段只需要 UTF-8 字节，
// 在此实现最小兼容编码器，且与 TextEncoder 对无效代理对的处理一致。
function encodeUtf8 (value) {
  const bytes = []
  for (let index = 0; index < value.length; index += 1) {
    let codePoint = value.charCodeAt(index)
    if (codePoint >= 0xd800 && codePoint <= 0xdbff) {
      const next = value.charCodeAt(index + 1)
      if (next >= 0xdc00 && next <= 0xdfff) {
        codePoint = 0x10000 + ((codePoint - 0xd800) << 10) + (next - 0xdc00)
        index += 1
      } else {
        codePoint = 0xfffd
      }
    } else if (codePoint >= 0xdc00 && codePoint <= 0xdfff) {
      codePoint = 0xfffd
    }

    if (codePoint <= 0x7f) {
      bytes.push(codePoint)
    } else if (codePoint <= 0x7ff) {
      bytes.push(0xc0 | (codePoint >> 6), 0x80 | (codePoint & 0x3f))
    } else if (codePoint <= 0xffff) {
      bytes.push(0xe0 | (codePoint >> 12), 0x80 | ((codePoint >> 6) & 0x3f), 0x80 | (codePoint & 0x3f))
    } else {
      bytes.push(0xf0 | (codePoint >> 18), 0x80 | ((codePoint >> 12) & 0x3f), 0x80 | ((codePoint >> 6) & 0x3f), 0x80 | (codePoint & 0x3f))
    }
  }
  return new Uint8Array(bytes)
}

function ByteData (data) {
  this.mode = Mode.BYTE
  if (typeof (data) === 'string') {
    this.data = encodeUtf8(data)
  } else {
    this.data = new Uint8Array(data)
  }
}

ByteData.getBitsLength = function getBitsLength (length) {
  return length * 8
}

ByteData.prototype.getLength = function getLength () {
  return this.data.length
}

ByteData.prototype.getBitsLength = function getBitsLength () {
  return ByteData.getBitsLength(this.data.length)
}

ByteData.prototype.write = function (bitBuffer) {
  for (let i = 0, l = this.data.length; i < l; i++) {
    bitBuffer.put(this.data[i], 8)
  }
}

module.exports = ByteData