Setting image from gallery as dynamic background image to pages

Hello,

I am developing app using Xamarin.Forms. I have a requirement where in user can select any image from gallery and should be able to set as background image on all the pages.

1. I understand there is a backgroundImage property in Page control to which background can be set however its value can only be assigned to inbuilt resources images (i.e. images which are part of project as resource) and I can't assign the gallery image here. If I'm not correct then pls point me the way how to use non resources image.

2. Also, I want the set background Image to all the pages once setting is done. How I can apply the image to all the pages simultaneously?

Any pointer/help will be much appreciated.

Regards,