Not scanning white barcodes

[Mbengparis]

Describe the bug
Nothing happens when white codes are scanned.

To Reproduce
Steps to reproduce the behavior:

Go to https://blog.minhazav.dev/research/html5-qrcode
Request camera permissions
Scan any white barcode
Nothing happens

Expected behavior
It is supposed to show the link of the barcode

Tested on iOS and android.

[Gspohu]

I can confirm, I use this in my Svelte WebApp and White QrCode aren't recognized.

Tested with this one

[Mbengparis]

i finally got it to work by tweaking the code. I added the inverter_counter and the invert variable. The invert variable checks if the code has been inverted or not.

Use this part in the class B extends O as follows:

class B extends O {
constructor(t) { super(t.width, t.height), this.canvas = t, this.tempCanvasElement = null, this.buffer = B.makeBufferFromCanvasImageData(t) } static makeBufferFromCanvasImageData(t) {
const e = t.getContext("2d").getImageData(0, 0, t.width, t.height);
return B.toGrayscaleBuffer(e.data, t.width, t.height)
}

            static inverter_counter=0;
            static toGrayscaleBuffer(t, e, r) { 
               B.inverter_counter++; 
               var invert=(B.inverter_counter % 4 === 2 || B.inverter_counter % 4 === 3);

                const n = new Uint8ClampedArray(e * r); 
                 for (let e = 0, r = 0, i = t.length; e < i; e += 4, r++) { 
                  let i; 
                   i = 0 === t[e + 3] ? 255 : 306 * t[e] + 601 * t[e + 1] + 117 * t[e + 2] + 512 >> 10, 
                   n[r] = invert?(255-i):i 
                } 
                   return n 

            }

[Gspohu]

Oh, finally this issue is duplicated here: #94

and there is a PR in progress on this topic here: #766
but it seems dead.

Regarding what you're saying, @Mbengparis what are you modifying and where?

[Mbengparis]

Before you use the library, you have to import it to your site. Open the code in the library you have imported, and search for the class B extends O. In there you will see a code similar to what i posted but without the inverter_counter and the invert variables. Just add as i wrote it up there.