code: @Override
      public Animator getInAnimator(View target, SlideShowView parent, int fromSlide, int toSlide) {
          target.setAlpha(1);
          target.setScaleX(1);
          target.setScaleY(1);
          target.setTranslationX(0);
          target.setTranslationY(0);
  
          final PropertyValuesHolder rotation;
          final PropertyValuesHolder alpha = PropertyValuesHolder.ofFloat(View.ALPHA, 0, 1);
  
          switch (axis) {
              case VERTICAL:
                  target.setRotationX(-90);
                  target.setRotationY(0);
                  rotation = PropertyValuesHolder.ofFloat(View.ROTATION_X, 0);
                  break;
  
              case HORIZONTAL:
              default:
                  target.setRotationX(0);
                  target.setRotationY(-90);
                  rotation = PropertyValuesHolder.ofFloat(View.ROTATION_Y, 0);
                  break;
          }
  
          ObjectAnimator animator = ObjectAnimator.ofPropertyValuesHolder(target, rotation/*, alpha*/);
          animator.setDuration(getDuration()/2);
          animator.setStartDelay(getDuration()/2);
          animator.setInterpolator(getInterpolator());
  
          return animator;
      }
docs: ==