将Base64字符串图像转换为Uint8ClampedArray

问题描述：

我有从 Expo ImagePicker组件返回的base64格式的图像数据，并且我想将其转换为[r0，g0，b0，a0，r1，g1，b1，a1，...]形式的RGBA像素值的Uint8ClampedArray，因为它是

I have imagedata in base64 format returned from Expo ImagePicker component, and I want to convert it to An Uint8ClampedArray of RGBA pixel values in the form [r0, g0, b0, a0, r1, g1, b1, a1, ...], cause it's the only input accepted by jsQR library

我尝试了这个，但是没有用:

I tried this, but did not work:

const dataURItoBlob = byteString  => {

  // write the bytes of the string to a typed array
  var ia = new Uint8ClampedArray(byteString.length);
  for (var i = 0; i < byteString.length; i++) {
    ia[i] = byteString.charCodeAt(i);
  }

  return ia;
};

任何帮助将不胜感激

答

我找到的解决方案如下:

The solution that I found is as follows:

它要求使用 typedarray ，jpeg-js

var Uint8ClampedArray = require('typedarray').Uint8ClampedArray;
const Buffer = require('buffer').Buffer;
global.Buffer = Buffer; // very important
const jpeg = require('jpeg-js');


const jpegData = Buffer.from(base64, 'base64');
var rawImageData = jpeg.decode(jpegData);

var clampedArray = new Uint8ClampedArray(rawImageData.data.length);
// manually fill Uint8ClampedArray, cause Uint8ClampedArray.from function is not available in react-native
var i;
for (i = 0; i < rawImageData.data.length; i++) {
  clampedArray[i] = rawImageData.data[i];
}

将Base64字符串图像转换为Uint8ClampedArray

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