Convert buffer to uInt8array

General
1

Hi guys,

I am using node-red to implement an ap and I am racking my brains to figure out how to a buffer to uint8array (I am not sure that is that type).

The node "jimp-image" of module "node-red-contrib-image-tools" outputs an image as a buffer or a base64 string. I need to pass the responsed image into a web service which requires an uint8array base image.

Below is the output buffer format from jimp-image:

2

But I need the following type of buffer:

1

Do you have any idea how to convert the buffer to an array buffer as showed into the attached image?

Thank you very much for any support you can provide.

2

Instances of Buffer are also instances of Uint8Array in node.js 4.x and higher. Thus, the most efficient solution is to access the buf.buffer property directly, as per node.js - Convert a binary NodeJS Buffer to JavaScript ArrayBuffer - Stack Overflow

3

Hi Steve,
Thank you for your prompt reply.

Looking into the stackoverflow post you sent, what I want is exactly the opposite of this answer...

"From ArrayBuffer to Buffer" could be done this way:
var buffer = Buffer.from( new Uint8Array(ab) );

Do you have any idea how to do it, from Buffer to ArrayBuffer?

Thanks,

4

I dont know where you were reading?

image
image743×376 21.8 KB

demo...
image

try adding this to a function node after the image-tools output / before the http request...

let b = msg.payload; //get the image buffer
msg.payload = b.buffer.slice(b.byteOffset, b.byteOffset + b.byteLength);
return msg;
5

Hi Steve,

Sorry but this answer does not work.
It always returns an empty object not an array.

3
31401×392 21 KB

Am I doing something wrong?

Thank you for yor help.

6

No it's not. It's an ArrayBuffer. It states that in your screenshot. It's just that the debug output doesn't show you the contents like it does for a buffer.

Also, why have you used the hardcored buffer and not the payload from the image?

I have a feeling you don't know precisely what you are supposed to send to this API. It is quite possible a buffer sent with the correct headers etc will work perfectly fine.

Can you clarify that. Perhaps a link to documentation?

7

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