Listen to EditText OnFocusChangeListener Globally

Question

I am interested in building a system application for Android which can globally listen to all EditText on focus change event, somehow I am gonna provide certain service when the user gain focus on any EditText.

I have successfully downloaded AOSP(Android Open Source Project) and I want to start writing my app as system application.

My question is can I do that as a system application "listening to global events" ?

if possible what are they areas I need to dig up to learn more about gaining such a privilege.

Any suggestion or help would be greatly appreciated.

Answer 1

I suggest you start by looking at View.java class which basically has the basic building block for user interface component.

../frameworks/base/core/java/android/view/View.java

and lookup the method onFocusChanged if you are only interested in EditText add the following line

 if (this instanceof EditText) {
      Toast.makeText(getContext(), "focus gained!", Toast.LENGTH_SHORT).show(); 
 }

build again and you will see toast notification everytime you gain focus to any EditText around the OS