[QUESTION] Resize image before adding it as base64

I'm currently adding images to the canvas as base64 (embedAsBase64: true). I don't want to upload the image for the moment, to keep things simple. But, I want to be able to resize or crop the image before adding it through the asset manager as base64, to avoid oversized images added by the user.

Basically I would need an event before the image is added, so I can transform the image, but for now we only have access to asset:add event. Any ideas if this would be possible ?

Thanks