Displaying card flip animation on old android

We all know this article of how to create "card filp" animations using new api. But how can I make this on apis < 3.0?

Update:

As long as there are good and easy-to-use libraries like android-FlipView I don't think you really need to do such animation by yourself.

Found the answer. If you want to do flip animation on ALL ANDROID VERSIONS, use this:

Activity layout file:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/main_activity_root"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="@android:color/transparent" >
 
<RelativeLayout
android:id="@+id/main_activity_card_face"
android:layout_width="300dp"
android:layout_height="407dp"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:background="@drawable/front"
android:clickable="true"
android:onClick="onCardClick"
android:padding="5dp" >
</RelativeLayout>
 
<RelativeLayout
android:id="@+id/main_activity_card_back"
android:layout_width="300dp"
android:layout_height="407dp"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:background="@drawable/back"
android:clickable="true"
android:onClick="onCardClick"
android:visibility="gone" >
</RelativeLayout>
 
</RelativeLayout>

As the layout file flips two view groups you could put anything else inside the view group and it should work. Now lets look at the methods inside the activity which handles calling the flip animation code:

public void onCardClick(View view)
{
      flipCard();
}
 
private void flipCard()
{
    View rootLayout = findViewById(R.id.main_activity_root);
    View cardFace = findViewById(R.id.main_activity_card_face);
    View cardBack = findViewById(R.id.main_activity_card_back);
 
    FlipAnimation flipAnimation = new FlipAnimation(cardFace, cardBack);
 
    if (cardFace.getVisibility() == View.GONE)
    {
        flipAnimation.reverse();
    }
    rootLayout.startAnimation(flipAnimation);
}

And finally the FlipAnimation class:

public class FlipAnimation extends Animation
{
    private Camera camera;
 
    private View fromView;
    private View toView;
 
    private float centerX;
    private float centerY;
 
    private boolean forward = true;
 
    /**
     * Creates a 3D flip animation between two views.
     *
     * @param fromView First view in the transition.
     * @param toView Second view in the transition.
     */
    public FlipAnimation(View fromView, View toView)
    {
        this.fromView = fromView;
        this.toView = toView;
 
        setDuration(700);
        setFillAfter(false);
        setInterpolator(new AccelerateDecelerateInterpolator());
    }
 
    public void reverse()
    {
        forward = false;
        View switchView = toView;
        toView = fromView;
        fromView = switchView;
    }
 
    @Override
    public void initialize(int width, int height, int parentWidth, int parentHeight)
    {
        super.initialize(width, height, parentWidth, parentHeight);
        centerX = width/2;
        centerY = height/2;
        camera = new Camera();
    }
 
    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t)
    {
        // Angle around the y-axis of the rotation at the given time
        // calculated both in radians and degrees.
        final double radians = Math.PI * interpolatedTime;
        float degrees = (float) (180.0 * radians / Math.PI);
 
        // Once we reach the midpoint in the animation, we need to hide the
        // source view and show the destination view. We also need to change
        // the angle by 180 degrees so that the destination does not come in
        // flipped around
        if (interpolatedTime >= 0.5f)
        {
            degrees -= 180.f;
            fromView.setVisibility(View.GONE);
            toView.setVisibility(View.VISIBLE);
        }
 
        if (forward)
            degrees = -degrees; //determines direction of rotation when flip begins
 
        final Matrix matrix = t.getMatrix();
        camera.save();
        camera.rotateY(degrees);
        camera.getMatrix(matrix);
        camera.restore();
        matrix.preTranslate(-centerX, -centerY);
        matrix.postTranslate(centerX, centerY);
    }

Here is the link for original post: Displaying card flip animation on old android

UPDATE from @FMMobileFelipeMenezes .

if you want the animation with a smooth scale to flip, change this part of code to (applyTransformation) :

final Matrix matrix = t.getMatrix();
camera.save();
camera.translate(0, 0, Math.abs(degrees)*2);
camera.getMatrix(matrix);
camera.rotateY(degrees);
camera.getMatrix(matrix);
camera.restore();
matrix.preTranslate(-centerX, -centerY);
matrix.postTranslate(centerX, centerY);

UPDATE from @Hesam There is good tutorial that I recommend to read it. Although it's not as nice as Android tutorial based on fragments, it's worth to be read and useful if you want to assign animation to layouts and views as well as have it on old APIs.

Use Android's scale animation to simulate a 3D flip

Improved project on github by @LenaBru