private void doAnimationZIndex(ZIndexTransformer transformer, CardItem card, float fraction,
                                   float fractionInterpolated, int fromPosition, int toPosition) {
        transformer.transformAnimation(card, fraction, mCardWidth,
                mCardHeight, fromPosition, toPosition);
        if (mAnimInterpolator != null) {
            transformer.transformInterpolatedAnimation(card, fractionInterpolated, mCardWidth,
                    mCardHeight, fromPosition, toPosition);
        }
    }
do calculation for card Z index

@param transformer          Z index transformer
@param card                 card item
@param fraction             animation progress from 0.0f to 1.0f
@param fractionInterpolated interpolated animation progress
@param fromPosition         card moving from
@param toPosition           card moving to
infinite-cards/src/main/java/com/bakerj/infinitecards/CardAnimationHelper.java