Android实现listview滑动时渐隐渐现顶部栏实例代码

private void initListener() { lvList.setOnScrollChangeListener(new View.OnScrollChangeListener() { @Override public void onScrollChange(View v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) { } }); lvList.setOnScrollListener(new AbsListView.OnScrollListener() { @Override public void onScrollStateChanged(AbsListView view, int scrollState) { } @Override public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) { // Logger.myLog("firstVisibleItem=" + firstVisibleItem + "visibleItemCount=" + visibleItemCount + "totalItemCount=" + totalItemCount); Logger.myLog(getScroolY()+"top=" + gettop()); tvText.setAlpha(getAlphaFloat(getScroolY())); } }); } /** * 获取渐变透明值 * @param dis * @return */ public float getAlphaFloat(int dis){ int step = 5000; if(dis == 0){ return 0.0f; } if(dis < step){ return (float)(dis * (1.0/step)); }else{ return 1.0f; } } /** * 获取上滑的距离 * @return distance */ public int getScroolY(){ View c = lvList.getChildAt(0); if(null == c){ return 0; } int firstVisiblePosition = lvList.getFirstVisiblePosition(); int top = c.getTop(); /** * 声明一下，这里测试得到的top值始终是listview条目中显示的第一条距离顶部的距离， * 而这个在坐标中的表示是一个负数，所以需要对其取一个绝对值 */ return firstVisiblePosition * c.getHeight() + Math.abs(top); } /** * 获取首条距离顶部的高度 * @return distance top */ private int gettop(){ View c = lvList.getChildAt(0); if(null == c){ return 0; } return c.getTop(); }