我有从Expo ImagePicker component返回的base64格式的imagedata,我想将它转换成r0,g0,b0,a0,r1,g1,b1,a1等格式的RGBA像素值的Uint8ClampedArray,因为它是jsQR library唯一接受的输入
我试过了,但不起作用:
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;
};
我们将非常感谢您的帮助。
发布于 2018-09-09 04:24:53
我找到的解决方案如下:
需要使用typedarray、Buffer、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];
}
发布于 2020-02-19 07:33:35
我猜您的base64编码的URI实际上是一个PNG,所以您可以执行以下操作:
const {PNG} = require('pngjs');
const jsqr = require('jsqr');
const dataUri = 'data:image/png;base64,ABCDEFYOURIMAGEHEREABCDEF';
const png = PNG.sync.read(Buffer.from(dataUri.slice('data:image/png;base64,'.length), 'base64'));
const code = jsqr(Uint8ClampedArray.from(png.data), png.width, png.height);
// code.data now contains the URL string encoded by the QR code
发布于 2018-08-21 20:48:10
react native的新答案:
这个包应该可以做到这一点。如果它起作用了,请告诉我。
https://www.npmjs.com/package/get-image-data
用于浏览器的旧浏览器:
首先将base64 img放在画布中,如下所示:
Base64 PNG data to HTML5 canvas
然后在canvas
上应用ImageData
(https://developer.mozilla.org/en-US/docs/Web/API/ImageData)
这应该会给你想要的结果。
https://stackoverflow.com/questions/51948472
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