<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
....

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android" >
    <item android:drawable="@drawable/btn2" android:state_pressed="true" />
    <item android:drawable="@drawable/btn_main" />
</selector>

android:background="@drawable/buttonsel"

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:paddingbottom="0sp" android:state_pressed="true"/>
    <item android:paddingbottom="17sp" android:state_focused="true"/>
    <item android:paddingbottom="17sp"/>
</selector>

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/b3" android:state_pressed="true" />
    <item android:drawable="@drawable/b2" android:state_focused="true" />
    <item android:drawable="@drawable/b1" android:paddingbottom="16sp" />
</selector>

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
    <item>
        <bitmap          android:src="@drawable/b3"        />
        <padding
            android:bottom="200dp"
            android:left="0dp"
            android:right="200dp"
            android:top="0dp" />
    </item>
</layer-list>

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/[color=red]button_pressed[/color]" android:state_pressed="true" />
    <item android:drawable="@drawable/b2" android:state_focused="true" />
    <item android:drawable="@drawable/b1"/>
</selector>

Button btn1 = (Button) findViewById(R.id.mybtn1);
btn1.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
.....

btn1.setText(Integer.toString(btn1.getHeight()) + "/ " + Float.toString(btn1.getTextSize()));

btn1.measure(View.MeasureSpec.UNSPECIFIED, View.MeasureSpec.UNSPECIFIED);

btn1.setTextSize((int) (btn1.getMeasuredHeight()*0.25));

btn1.setText(Integer.toString((int) btn1.getTextSize())+"/ "+Integer.toString((int) (btn1.getMeasuredHeight()*0.25)));

        btn1.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                if (event.getAction() == MotionEvent.ACTION_UP) {
                    // кусок кода, форматирующий надпись на кнопке
                    ...
                } else if (event.getAction() == MotionEvent.ACTION_DOWN) {
                    // точно такой же кусок кода, но со смещением
                    ...
                }
                return false;
            }
        });