How to change rotation in KeyAttribute in MotionLayout programatically - android-animation

Question

I need to change rotation from 30 to -30 degrees while motion scene repeating. How to do this programatically?
R.xml.scene_01:
<MotionScene
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:motion="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<Transition
motion:constraintSetStart="#id/start"
motion:constraintSetEnd="#id/end"
motion:duration="2000">
<KeyFrameSet>
<KeyAttribute
android:rotation="30"
motion:target="#id/button"
android:scaleX="1.3"
android:scaleY="1.3"
motion:framePosition="50"/>
</KeyFrameSet>
</Transition>
<ConstraintSet android:id="#+id/start">
<Constraint
android:id="#id/button"
android:layout_width="64dp"
android:layout_height="64dp"
android:src="#drawable/tut_ali_icon"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</ConstraintSet>
<ConstraintSet android:id="#+id/end">
<Constraint
android:id="#id/button"
android:layout_width="64dp"
android:layout_height="64dp"
android:src="#drawable/tut_ali_icon"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</ConstraintSet>
</MotionScene>
Listener in MotionLayout:
#Override
public void onViewCreated(#NonNull View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
mMotionLayout.setTransitionListener(new MotionLayout.TransitionListener() {
#Override
public void onTransitionChange(MotionLayout motionLayout, int i, int i1, float v) {
}
#Override
public void onTransitionCompleted(MotionLayout motionLayout, int currentId) {
if(currentId == R.id.end){
motionLayout.loadLayoutDescription(R.xml.scene_02);
motionLayout.transitionToStart();
}else{
motionLayout.loadLayoutDescription(R.xml.scene_01);
motionLayout.transitionToEnd();
}
}
});
mMotionLayout.transitionToEnd();
}
I need to change rotation in onTransitionCompleted method. As an option maybe can I create KeyFrameSet which using various KeyAttribute?
In R.xml.scene_02 I change only android:rotation="-30" but it seems loadLayoutDescription method doesn't work.
Such a movement as in the picture I want to get:
enter image description here

Answer 1

Not enough rep to comment, but why do you have 2 separate transitions specified?
Trying to understand the question, if you want it to consistently rotate with that listener, the following should work:
<Transition
motion:constraintSetEnd="#id/end"
motion:constraintSetStart="#id/start"
motion:duration="2000">
<KeyFrameSet>
<KeyAttribute
android:rotation="-45"
android:scaleX="2"
android:scaleY="2"
motion:framePosition="0"
motion:target="#id/button" />
<KeyAttribute
android:rotation="45"
android:scaleX="2"
android:scaleY="2"
motion:framePosition="50"
motion:target="#id/button" />
<KeyAttribute
android:rotation="-45"
android:scaleX="2"
android:scaleY="2"
motion:framePosition="100"
motion:target="#id/button" />
</KeyFrameSet>
</Transition>
This will have the button start and end at -45 degrees rotation and, halfway through the transition, will rotate to 45 degrees. Note that these are just value animations so they will NOT be applied to the object when it reaches the start or end - you'll need to specify the rotation in the start/end ConstraintSet attributes.