Created
January 11, 2023 02:03
Generate BlurHash
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const digitCharacters = [ | |
'0', | |
'1', | |
'2', | |
'3', | |
'4', | |
'5', | |
'6', | |
'7', | |
'8', | |
'9', | |
'A', | |
'B', | |
'C', | |
'D', | |
'E', | |
'F', | |
'G', | |
'H', | |
'I', | |
'J', | |
'K', | |
'L', | |
'M', | |
'N', | |
'O', | |
'P', | |
'Q', | |
'R', | |
'S', | |
'T', | |
'U', | |
'V', | |
'W', | |
'X', | |
'Y', | |
'Z', | |
'a', | |
'b', | |
'c', | |
'd', | |
'e', | |
'f', | |
'g', | |
'h', | |
'i', | |
'j', | |
'k', | |
'l', | |
'm', | |
'n', | |
'o', | |
'p', | |
'q', | |
'r', | |
's', | |
't', | |
'u', | |
'v', | |
'w', | |
'x', | |
'y', | |
'z', | |
'#', | |
'$', | |
'%', | |
'*', | |
'+', | |
',', | |
'-', | |
'.', | |
':', | |
';', | |
'=', | |
'?', | |
'@', | |
'[', | |
']', | |
'^', | |
'_', | |
'{', | |
'|', | |
'}', | |
'~', | |
]; | |
const decode83 = (str: string) => { | |
let value = 0; | |
for (let i = 0; i < str.length; i++) { | |
const c = str[i]; | |
const digit = digitCharacters.indexOf(c); | |
value = value * 83 + digit; | |
} | |
return value; | |
}; | |
const makeId = (length: number) => { | |
let result = ''; | |
const characters = '1234567890'; | |
const charactersLength = characters.length; | |
for (let i = 0; i < length; i++) { | |
result += characters.charAt(Math.floor(Math.random() * charactersLength)); | |
} | |
return parseInt(result, 10); | |
}; | |
export const generateBlurHash = () => { | |
const number = Math.ceil(Math.random() * 265); | |
const n = makeId(number); | |
let result = ''; | |
for (let i = 1; i <= (number * 1024); i++) { | |
const digit = (Math.floor(n) / 83 ** ((number / 128) - i)) % 83; | |
result += digitCharacters[Math.floor(digit)]; | |
} | |
const sizeFlag = decode83(result[0]); | |
const numY = Math.floor(sizeFlag / 9) + 1; | |
const numX = (sizeFlag % 9) + 1; | |
return result.slice(0, 4 + 2 * numX * numY); | |
}; |
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