Custom Android switch track 'animation'

Question

I've created a basic custom Switch, as defined below.

<Switch
        android:id="@+id/availSwitch"
        android:layout_width="wrap_content"
        android:switchMinWidth="110dp"
        android:layout_height="wrap_content"
        android:track="@drawable/switch_track"
        android:thumb="@drawable/thumb"/>

The @drawable/thumb is a simple PNG which works fine.

The @drawable/switch_track is defined below. @drawable/trackon and @drawable/trackoff are PNG's.

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_checked="false" android:drawable="@drawable/trackoff" />
    <item android:state_checked="true"  android:drawable="@drawable/trackon" />
    <item                               android:drawable="@drawable/trackoff" />

</selector>

This switch looks and works as intended for the most part, but is there some way to 'animate' the track as the thumb travels over it on user drag? Either fade between checked and unchecked, or preferably change 'behind' the thumb.

The current behaviour is shown below.

Answer 1

There was a time I was also looking for the same when I needed a toggle button functionality similar to native iOS which can be dragged to on/off for one of my projects. At that time I searched hard and I found this library.

https://github.com/pellucide/Android-Switch-Demo-pre-4.0

So hope this is what you are looking for too.