Android ObjectAnimator vs ViewPropertyAnimator

Question

What's the difference between ObjectAnimator and ViewPropertyAnimator changing property value?

ObjectAnimator objectAnimator = ObjectAnimator.ofFloat(myObject, "X", 0.0f, 100.0f);

I tried myObject.getX() while above objectAnimator is ongoing, and I got a on-the-way value between 0.0f to 100.0.

myObject.setX(0.0f);
myObject.animate().x(100.0f);

However, I got precise 100.0 when I myObject.getX()'d while above ViewPropertyAnimator is ongoing.

I can't figure out what makes this difference.

Thanks in advance.

Showcase

Answer 1

When you request to animate the x field using a ViewPropertyAnimator, it doesn't actually animate the x field - it animates the translateX field. This is why you can't see the x field change.

From the Android source code in ViewPropertyAnimator.java:

case X:
    renderNode.setTranslationX(value - mView.mLeft);
    break;

ObjectAnimator on the other hand uses reflection to animate properties - rather than a preset list of supported actions. And so when you tell it to animate the "X" field, it calls "setX" directly.

Leonard

What about ViewPropertyAnimator.translationX()? Does that mean ViewPropertyAnimator.x() and translationX() are actually the same? – Showcase

translationX also affects the translationX, just without compensating with the view's mLeft value. – Leonard

I don't think this answer is correct. Do you have any reference? – Kemper

Yes, the android source code (see method setValue(int, float)): github.com/android/platform_frameworks_base/blob/master/core/… – Leonard

How about using ViewPropertyAnimator.x() ? This will play with the actual position of the view. – Exordium

Please check this issue #49044588 @GilMoshayof – Satchel

i don't think this is true anymore (Android 28 code does not do this) – Ingraham