Android开发之ListView的head消失页面导航栏的渐变出现和隐藏

<RelativeLayoutxmlns:android="http://schemas.android.com/apk/res/android"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"xmlns:ptr="http://schemas.android.com/apk/res-auto"tools:context=".fragment.home.HomeStoreFragment"><com.handmark.pulltorefresh.library.PullToRefreshListViewandroid:id="@+id/lv_home_store_list"android:layout_width="match_parent"android:layout_height="match_parent"ptr:ptrDrawable="@drawable/default_ptr_flip"ptr:ptrAnimationStyle="flip"/><!--top 搜索栏--><LinearLayoutandroid:id="@+id/ll_top_search"android:layout_width="match_parent"android:layout_height="60dp"android:background="@color/zuti"android:visibility="invisible"><LinearLayoutandroid:layout_width="match_parent"android:layout_height="match_parent"android:layout_marginLeft="15dp"android:layout_marginRight="15dp"android:layout_marginTop="8dp"android:layout_marginBottom="8dp"android:background="@drawable/shape_edit_cornor"android:gravity="center"><ImageViewandroid:id="@+id/iv_search_icon"android:layout_width="30dp"android:layout_height="30dp"android:src="@drawable/icon_navbar_search"android:layout_marginRight="5dp"/><EditTextandroid:id="@+id/et_store_search"android:layout_width="wrap_content"android:layout_height="wrap_content"android:hint="输入商家或商品名"android:textColorHint="@color/shenhui"android:background="@null"/></LinearLayout></LinearLayout></RelativeLayout>

private boolean isFlingScroll;private View headView;private PullToRefreshListView lvHomeStore;initView(){lvHomeStore = (PullToRefreshListView) view.findViewById(R.id.lv_home_store_list);lvHomeStore.setMode(PullToRefreshBase.Mode.BOTH);ListView listView = lvHomeStore.getRefreshableView();headView = initHeadView();AbsListView.LayoutParams layoutParams = new AbsListView.LayoutParams(AbsListView.LayoutParams.MATCH_PARENT, AbsListView.LayoutParams.WRAP_CONTENT);//这句要加上去headView.setLayoutParams(layoutParams);listView.addHeaderView(headView);lvHomeStore.setAdapter(adapter);lvHomeStore.setOnScrollListener(this);}@Overridepublic void onScrollStateChanged(AbsListView view, int scrollState) {if (scrollState == SCROLL_STATE_FLING) {//手指离开手机界面，Listview还在滑动isFlingScroll = true;} else if (scrollState == SCROLL_STATE_TOUCH_SCROLL) {//手指在界面上滚动的情况isFlingScroll = false;}}@Overridepublic void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {showSearchBarShow();}private void showSearchBarShow() {int headBottomToParentTop = headView.getHeight() + headView.getTop();Log.d("homeStore", "headView.getHeight(): " + headView.getHeight());Log.d("homeStore", "headView.getTop(): " + headView.getTop());Log.d("homeStore", "headBottomToParentTop: " + headBottomToParentTop);if (!isFlingScroll) {//手指在界面滑动的情况int height = layoutSearch.getHeight();Log.d("homeStore", "height: " + height);if (headBottomToParentTop > height) {layoutSearch.setVisibility(View.INVISIBLE);} else if (headBottomToParentTop <= height) {//缓慢滑动，这部分代码工作正常，快速滑动，里面的数据就跟不上节奏了。float alpha = (height - headBottomToParentTop) * 1f / height;Log.d("homeStore", "alpha: " + alpha);layoutSearch.setAlpha(alpha);layoutSearch.setVisibility(View.VISIBLE);}if (!headView.isShown()){//解决快速滑动，上部分代码不能正常工作的问题。layoutSearch.setAlpha(1);layoutSearch.setVisibility(View.VISIBLE);}} else {//手指离开，listview还在滑动，一般情况是列表快速滑动，这种情况直接设置导航栏的可见性if (!headView.isShown()) {if (!layoutSearch.isShown()){layoutSearch.setVisibility(View.VISIBLE);layoutSearch.setAlpha(1);}} else {if (layoutSearch.isShown()){layoutSearch.setVisibility(View.INVISIBLE);}}}}