menduner/src/utils/index.js

export const blobToJson = (blob) => {
  return new Promise((resolve, reject) => {
    const reader = new FileReader()

    reader.onload = function (event) {
      const jsonString = event.target.result
      const jsonObject = JSON.parse(jsonString)
      resolve(jsonObject)
    }

    reader.onerror = function (error) {
      reject(error)
    }

    reader.readAsText(blob)
  })
}

// 判断是图片还是视频
export const checkIsImage = (url) => {
  var link = new URL(url)
  var path = link.pathname
  var extension = path.split('.').pop().toLowerCase()
  var imageExtensions = ['jpg', 'jpeg', 'gif', 'png']
  var videoExtensions = ['mp4', 'wmv', 'avi', 'mov']

  // 图片
  if (imageExtensions.includes(extension)) {
    return true
  }

  // 视频
  if (videoExtensions.includes(extension)) {
    return false
  }

  return null
}

// 预览文件
import { Base64 } from 'js-base64'
export const previewFile = (url) => {
  const baseUrl = import.meta.env.VITE_PREVIEW_URL
  window.open(`${baseUrl}/onlinePreview?url=${encodeURIComponent(Base64.encode(url))}`)
}

export const generateUUID = () => {
  var d = new Date().getTime()
  if (window.performance && typeof window.performance.now === "function") {
    d += performance.now(); //use high-precision timer if available
  }
  var uuid = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function (c) {
    var r = (d + Math.random() * 16) % 16 | 0
    d = Math.floor(d / 16)
    return (c == 'x' ? r : (r & 0x3 | 0x8)).toString(16)
  })
  return uuid.replace(/-/g, "")
}

export const downloadBase64 = (content, fileName) => {
  const base64ToBlob = function (code) {
    let parts = code.split(';base64,')
    let contentType = parts[0].split(':')[1]
    let raw = window.atob(parts[1])
    let rawLength = raw.length
    let uInt8Array = new Uint8Array(rawLength)
    for (let i = 0; i < rawLength; ++i) {
      uInt8Array[i] = raw.charCodeAt(i)
    }

    return new Blob([uInt8Array], {
      type: contentType
    })
  }
  let aLink = document.createElement('a')
  let blob = base64ToBlob(content)
  aLink.download = fileName + '.png'
  aLink.href = URL.createObjectURL(blob)
  aLink.click()
}

export const DPR = () => {
  // 获取设备dpi
  if (window.devicePixelRatio && window.devicePixelRatio > 1) {
    return window.devicePixelRatio * 2
  }
  // 直接返回高像素比
  return 8
}

// 文件下载 
export const getBlob = (url) => {
  return new Promise(resolve => {
    const xhr = new XMLHttpRequest()
    xhr.open('GET', url, true)
    xhr.responseType = 'blob'
    xhr.onload = () => {
      if (xhr.status === 200) resolve(xhr.response)
    }
    xhr.send()
  })
}

export const saveAs = (blob, filename) => {
  var link = document.createElement('a')
  link.href = window.URL.createObjectURL(blob)
  link.download = filename
  link.click()
}