Question

In my application I’m doing the following (using the support library):

FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.setCustomAnimations(R.anim.fade_in, R.anim.fade_out);
transaction.replace(R.id.fragment_container, fragment);
transaction.commit();

The animations R.anim.fade_in and R.anim.fade_out have less than 200 milliseconds duration.

The first time i change the fragment, the animation doesn’t show at all. I think it is due to XML inflating: the time it takes to inflate XML is bigger than the duration of the animation. From the second time on, the animation displays correctly.

Is there a way to preload an XML animation?

Answer 1

I found it myself. You have to override the onCreateAnimation() method in your Fragment. This is how I did it:

@Override
public Animation onCreateAnimation(int transit, boolean enter, int nextAnim) {
    if (enter)
        return mEnterAnimation;
    else
        return mExitAnimation;
}

private static final Animation mEnterAnimation = AnimationUtils
    .loadAnimation(MyApplication.getInstance().getBaseContext(),
    R.anim.frag_fade_in);

private static final Animation mExitAnimation = AnimationUtils
    .loadAnimation(MyApplication.getInstance().getBaseContext(),
    R.anim.frag_fade_out);

Note that the mEnterAnimation and mExitAnimation fields are declared static. To load an animation via AnimationUtils.loadAnimation() you need a Context. The Context is obtained via the MyApplication singleton. To create such a singleton just write into your AndroidManifest.xml:

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.app"
    android:versionCode="1"
    android:versionName="1.0" >

    <application
        android:name=".MyApplication"
        android:label="@string/app_name" >

        <!-- Insert your activities here -->

    </application>

</manifest>

Then create the class com.example.app.MyApplication as a singleton:

public class MyApplication extends Application {
    public static MyApplication getInstance() {
        return mInstance;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        mInstance = this;
    }

    private static MyApplication mInstance;
}