Problems with Objectanimator

Question

I’m doing an animation where an image slides from the bottom up using Objectanimator. In the emulator of Android Studio the animation occurs perfectly, but when I run on Android devices (tested in more than two), the animation seems to jump.

Here is the code:

imgAnim = (ImageView) findViewById(R.id.imagem);
ob = ObjectAnimator.ofFloat(imgAnim, "y", height, 70);
ob.setDuration(2100);
ob.start();

Answer 1

Jump is due to variable value height not be the value of the position y where Imageview is located.

When starting the animation the image "jumps" from its position to the position height and only then is the gentle movement started between height and 70.

So there’s no jump, height must have the value of the position y imageview:

height = imgAnim.getY();

Note:

The method getY() will return 0 if used in the onCreate(), then the views had not yet been scaled or positioned.

If the code you posted is not in the onCreate() nor is being called from it change the line

ob = ObjectAnimator.ofFloat(imgAnim, "y", height, 70);

for

ob = ObjectAnimator.ofFloat(imgAnim, "y", imgAnim.getY(), 70);

If you are, you need to ensure that it is executed after the views have been scaled and positioned.

To do this create a method to put the code of the animation:

private void animateImage(ImageView imageView, float startY, float endY){

    ObjectAnimator ob = ObjectAnimator.ofFloat(imageView, "y", startY, endY);
    ob.setDuration(2100);
    ob.start();
}

In the method onCreate(), add an Ongloballayoutlistener to Imageview and call the method animateImage() in the method onGlobalLayout():

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ....
    ....
    imgAnim = (ImageView) findViewById(R.id.imagem);
    imgAnim.getViewTreeObserver().addOnGlobalLayoutListener(new 

        ViewTreeObserver.OnGlobalLayoutListener() {
            @Override
            public void onGlobalLayout() {

                //Remove o listenner para não ser novamente chamado.
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                    imgAnim.getViewTreeObserver().removeOnGlobalLayoutListener(this);
                } else {
                    //noinspection deprecation
                    imgAnim.getViewTreeObserver().removeGlobalOnLayoutListener(this);
                }

                //Aqui a ImageView já foi dimensionada e posicionada
                //inicia a animação
                animateImage(imgAnim, imgAnim.getY(), 70);
            }
        });
}