preview-utils

web client preview utils

install

npm i preview-utils

base64 utils

parseBase64

const {content,contentType} = parseBase64(base64)

return base64 contentType and content

fileToBase64

const base64 =await  fileToBase64(file)

convert a file object to base64,this is a promise

imageToBase64

const base64 = imageToBase64(image)
// args (image, type = 'image/png', quality = .8)

convert a html image object to base64 ,use canvas,this is a sync function

imageToBlob

const file = imageToFile(image)

convert a html image object to blob

imageToFile

const blob = imageToBlob(image,"file.png")
//args (image, fileName, { lastModified = Date.now() } = {})

convert a html image object to File

imageUrlToBase64

const base64 = await imageUrlToBase64(url)

use a image url (the url allow cross domain ) from remote ,convert to base64

blobToFile

const file =  blobToFile(blob)
//args  (blob, fileName, { contentType, lastModified = Date.now() } = {}) 

convert a blob to File

base64ToBlob

const blob =  base64ToBlob(base64)

convert a base64 to Blob

base64ToFile

const file =  base64ToFile(base64,"file.txt")
//args (base64, fileName, { contentType, lastModified = Date.now() } = {}) 

convert a base64 to File

urlToBlob

const blob = await urlToBlob(url)
 

fetch a remote url as Blob

urlToFile

const file = await urlToFile(url,"image.png")
//args  (url, fileName, { contentType, lastModified = Date.now() } = {})

fetch a remote url as File

createThumb

const thumbBase64 = await createThumb(url,100,100)
//args   (file, width, height, { timeout = 2048, currentTime = 1, type = "image/png", quality = .8,toBlog=false } = {})
//file type:File,Image,HTMLVideoElement

create File | Image | Video 's thumb base64，

creatPreviewUrl

const url = await creatPreviewUrl(file)
//args  (file, timeout = 2048) 

use URL.createObjectURL(file) to create url，and use settimeout to revokeObjectURL