protected void onPreTransform(View view, float position) {
        final float width = view.getWidth();

        ViewHelper.setRotationX(view,0);
        ViewHelper.setRotationY(view,0);
        ViewHelper.setRotation(view,0);
        ViewHelper.setScaleX(view,1);
        ViewHelper.setScaleY(view,1);
        ViewHelper.setPivotX(view,0);
        ViewHelper.setPivotY(view,0);
        ViewHelper.setTranslationY(view,0);
        ViewHelper.setTranslationX(view,isPagingEnabled() ? 0f : -width * position);

        if (hideOffscreenPages()) {
            ViewHelper.setAlpha(view,position <= -1f || position >= 1f ? 0f : 1f);
        } else {
            ViewHelper.setAlpha(view,1f);
        }
        if(mCustomAnimationInterface != null){
            if(h.containsKey(view) == false || h.get(view).size() == 1){
                if(position > -1 && position < 1){
                    if(h.get(view) == null){
                        h.put(view,new ArrayList<Float>());
                    }
                    h.get(view).add(position);
                    if(h.get(view).size() == 2){
                        float zero = h.get(view).get(0);
                        float cha = h.get(view).get(1) - h.get(view).get(0);
                        if(zero > 0){
                            if(cha > -1 && cha < 0){
                                //in
                                mCustomAnimationInterface.onPrepareNextItemShowInScreen(view);
                            }else{
                                //out
                                mCustomAnimationInterface.onPrepareCurrentItemLeaveScreen(view);
                            }
                        }else{
                            if(cha > -1 && cha < 0){
                                //out
                                mCustomAnimationInterface.onPrepareCurrentItemLeaveScreen(view);
                            }else{
                                //in
                                mCustomAnimationInterface.onPrepareNextItemShowInScreen(view);
                            }
                        }
                    }
                }
            }
        }
    }
Called each {@link #transformPage(View, float)} before {{@link #onTransform(View, float)} is called.

@param view
@param position
library/src/main/java/com/daimajia/slider/library/Transformers/BaseTransformer.java