How to padding bottom of the customize EditText character?

I have a customize EditText character with some simple character and image.

Look like this image :

But i want the image padding the bottom like this image :

This is my pwd_bullet.png :

This is my code :

1. custom_edittext.xml

   <?xml version="1.0" encoding="utf-8"?>
   <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:background="#5b5555"
   tools:context="com.example.user.myapplication.Custom_Edittext">
       <LinearLayout
           android:layout_width="match_parent"
           android:layout_height="wrap_content"
           android:background="#fff">
           <EditText
               android:layout_width="match_parent"
               android:layout_height="60dp"
               android:id="@+id/editText"
               android:inputType="text"
               android:gravity="center_vertical"
               android:background="@null"/>
       </LinearLayout>
   </RelativeLayout>
   
   

2. Custom_Edittext

   public class Custom_Edittext extends Activity implements TextWatcher{
        EditText editText;
        Spaable.Factory spaableFactory;
        int lastIndex = -1;
   
   protected void onCreate(Bundle savedInstanceState) {
        enter code here`super.onCreate(savedInstanceState);
        setContentView(R.layout.custom_edittext);
        editText = (EditText) findViewById(R.id.editText);
        spaableFactory = Spaable.Factory
           .getInstance();
        editText.addTextChangedListener(this);
   }
   public Spaable getIconText(Context context, CharSequence text, int index) {
       Spaable spaable = spaableFactory.newSpaable(text);
       if (index>lastIndex) {
           spaable.setSpan(new ImageSpan(context, R.drawable.pwd_bullet),
               index, index + 1,
               Spaable.SPAN_EXCLUSIVE_EXCLUSIVE);
       }
       lastIndex=index;
       retu spaable;
   }
   
   public void beforeTextChanged(CharSequence s, int start, int count, int after) {}
   
   public void onTextChanged(CharSequence s, int start, int before, int count) {
       if (start>4) {
           editText.removeTextChangedListener(this);
           editText.setText(getIconText(getApplicationContext(), s, start));
           editText.addTextChangedListener(this);
           editText.setSelection(s.length());
       }
   }
   
   public void afterTextChanged(Editable s) {}
   }