Android pop in animation

Question

I mave a floating action button in my app which I want to sort of pop in, where it is invisible and starts to grow to a size like 60dp and then resizes back to the normal size of 56dp. How can that be done? I know how to do a normal fade in animation, but not a pop in.

Answer 1

I would create a animation file in res/anim and use a sequential scale animation like so:

expand_in.xml

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

    <scale 
        android:fromXScale="0.0" 
        android:fromYScale="0.0"
        android:toXScale="1.1" <!--set the scale value here-->
        android:toYScale="1.1"
        android:pivotX="50%"
        android:pivotY="50%"
        android:duration="400"/> <!--length of first animation-->


    <scale 
        android:fromXScale="1.1" <!--From whatever scale you set in the first animation-->
        android:fromYScale="1.1"
        android:toXScale="1.0" <!--Back to normal size-->
        android:toYScale="1.0"
        android:pivotX="50%" 
        android:pivotY="50%"
        android:startOffset="400" <!--start 2nd animation when first one ends-->
        android:duration="400"/>
</set>

Then in your activity:

Animation expandIn = AnimationUtils.loadAnimation(this, R.anim.expand_in);
actionButton.startAnimation(expandIn);

Answer 2

I found that my animation was much smoother than the current accepted answer when I switched it to use the Overshoot Interpolator.

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
android:interpolator="@android:anim/overshoot_interpolator" >

<scale
    android:duration="700"
    android:fromXScale="0.0"
    android:fromYScale="0.0"
    android:pivotX="50%"
    android:pivotY="50%"
    android:toXScale="1.0"
    android:toYScale="1.0" />

</set>

Here is a video showing examples of the interpolators: https://www.youtube.com/watch?v=OMOJxBe9KGg

Here is where it's touched on in the Android documentation: https://developer.android.com/guide/topics/resources/animation-resource.html#View