Getting ImageData dynamically

[bbhopesh]

My use case is that I need to extract RGBA values of all the pixels. getImageData seemed the right way to do it but now its proving to be more complex than expected.

These are two big issues I am facing:

1. The image is not known statically. I need to initialize canvas with with a dynamic image uri which would be determined based on some user action. I couldn't find an example to draw a new image in the canvas dynamically. Can you please advise on this?
2. Ideally, I wouldn't want user to see the image on screen but I couldn't do it even for static images.