listview的item全部漏出來才顯示

lvMaster.setOnScrollListener(new ScrollListener() {
            @Override
            public void onScrollStateChanged(AbsListView absListView, int i) {
                super.onScrollStateChanged(absListView, i);
            }

            @Override
            public void onScroll(AbsListView absListView, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
                super.onScroll(absListView, firstVisibleItem, visibleItemCount, totalItemCount);
                View animView;
                for (int i = 0; i < visibleItemCount; i++) {
                    animView = lvMaster.getListView().getChildAt(i);
                    if (animView == null) {
                        continue;
                    }
                    if (getScroll(lvMaster.getListView()) <= 0 && visibleItemCount == 1) {
                        ViewHelper.setAlpha(animView, 1f);
                    } else {
                        if(animView.getBottom()<=lvMaster.getListView().getBottom()){
                            ViewHelper.setAlpha(animView, 1f);
                        }
                        else {
                            ViewHelper.setAlpha(animView, 0f);
                        }
                    }
                }
            }
        });

protected int getScroll(ListView listview) {
        int scrollY = 0;
        View c =  listview.getChildAt(0); //this is the first visible row
        if(c != null){
            scrollY = -c.getTop(); 
       return scrollY;
    }
}


getScroll