Attach a bitmap on another bitmap

Question

I have a class Building. It contains a _bitmap object, referenced to a drawable. I can draw it on an external View, where its canvas calls myBuilding.getBitmap().

Now I want to draw some windows on the building, but I need them to be "tied" to the building, so that translating the x and y of myBuilding, the windows move together.

Is there a way to attach a bitmap (window) on the main bitmap (building) in order to get the resulting building with windows, when I call myBuilding.getBitmap() ?

Thank you.