Android: Cannot get a StateList drawable to work

Issue

I'm trying to make a state list drawable to be used as a background for an image button.

I'm using these PNG files

and my state list selector is like this:

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

and the image button is like this:

<ImageButton
            android:id="@+id/play_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:background="@drawable/play_button_bg"
            />

but the button appears as it's having the large image and the background, when clicking on it nothing happens. what can be wrong here?

Solution

Ok, I managed to resolve it using a state list selector with layer lists like this:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true">
        <layer-list>
            <item>
                <bitmap android:src="@drawable/play_button_pressed" android:gravity="center" />
            </item>
        </layer-list>
    </item>
    <item android:state_focused="true">
        <layer-list>
            <item>
                <bitmap android:src="@drawable/play_button_pressed" android:gravity="center" />
            </item>
        </layer-list>
    </item>
    <item android:drawable="@drawable/play_button_normal" />
</selector>

The trick is in the bitmap's: android:gravity="center"

Answered By - Mina Wissa