Hi, I am struggling with xml layout in my android app... please help

here is what I want:

I have to display two poarts in one activity - image part and login component part which are in one linearLayout. When the device is landscape, I want it to be 30% screen for image and 70% for the linearLayout. Both should be centered in each region
In portrait mode, I want them to be displayed like image on the top and linearLayout on the bottom. Both should be centered as well.

in landscape mode:
[ imageView 30% image centered ][ linear layout 70% content centered]

in portrait mode
[ imageView fullwidth image centered ]
[ linear layout full width content centered]

How can I achieve this?

try fragments