I want to create a separate plugin/add-on android app which can be installed separately. The need is like WhatsApp wallpaper application which is a standalone app. It is opened when user clicks to change wallpaper and result reflects in WhatsApp. I have something similar need.
I have a Activity in App1 which needs to set its background image. And I have another app App2 which have a gallery of images. When the user clicks on a Button in App1 , App2 will be opened and upon selection of an image, it will return to App1 and set its background. Though App1 is already a 100+ MB app, so the idea is to have a separate plugin app for it.
I have tried below things so far. But wanted to know if there is an easy way to achieve it or some sort of guidance on it.
http://mylifewithandroid.blogspot.in/2010/06/plugins.html
http://blog.raffaeu.com/archive/2015/05/31/android-plugin-application.aspx
How to release application plugin using Android Market?
Some example of this kind app is Muzei , Textra sms, WhatsApp Wallpaper