Android Listview自定义部分标题

Question

如何在android中实现ListView的自定义部分或标题,如Instagram应用程序.

http://prsarahevans.com/wp-content/uploads/2011/06/photo.PNG

当向上滚动具有userpic的栏时,名称和时间仍然存在,当其他标题栏靠近它时,然后动画就像推它一样.

谢谢.

Answer 1

我能够通过在listview上使用滚动侦听器来解决此问题.(在2.1上测试)

让我们说对于每个列表行我有一个像下面那样的布局.有内容部分和标题部分.用于标题或内容的视图类型无关紧要.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" android:background="#FFFFFF">

    <ImageView
        android:id="@+id/content"
        android:layout_width="fill_parent"
        android:layout_height="300dp"
        android:scaleType="centerCrop" 
        android:src="@drawable/pic"
        android:background="#aaaaff" 
        android:layout_marginTop="40dp"/>

    <TextView
        android:id="@+id/header"
        android:layout_width="fill_parent"
        android:layout_height="40dp"
        android:padding="12dp"
        android:text="Deneme Row"
        android:textColor="#000000" 
        android:background="#99ffffff"/>
</RelativeLayout>

活动的测试布局如下所示:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <ListView
        android:id="@+id/list"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" >
    </ListView>
</LinearLayout>

最后,活动的代码如下.在这里,我必须有一个适配器,它使用ViewHolder来存储标题视图,还有一个变量来跟踪每个连续滚动事件(previousTop)的滚动变化.这是因为offsetTopAndBottom()更改了与其先前位置相关的视图的偏移量.

public class TestActivity extends Activity implements AbsListView.OnScrollListener{

    ListView list; 
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        list = (ListView) findViewById(R.id.list);
        list.setAdapter(new Adapter(this));        
        list.setOnScrollListener(this); 
    }

    @Override
    public void onScroll(AbsListView view, int firstVisibleItem,
            int visibleItemCount, int totalItemCount) {     
        //the listview has only few children (of course according to the height of each child) who are visible
        for(int i=0; i < list.getChildCount(); i++){
            View child = list.getChildAt(i);
            ViewHolder holder = (ViewHolder) child.getTag();

            //if the view is the first item at the top we will do some processing
            if(i == 0){             
                boolean isAtBottom = child.getHeight() <= holder.header.getBottom();
                int offset = holder.previousTop - child.getTop();
                if(!(isAtBottom && offset > 0)){                    
                    holder.previousTop = child.getTop();
                    holder.header.offsetTopAndBottom(offset);                   
                    holder.header.invalidate();
                }
            } //if the view is not the first item it "may" need some correction because of view re-use
            else if (holder.header.getTop() != 0) {
                int offset = -1 * holder.header.getTop(); 
                holder.header.offsetTopAndBottom(offset);
                holder.previousTop = 0;
                holder.header.invalidate();
            }
        }
    }

    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {}

    private static class Adapter extends ArrayAdapter<String> {
        public Adapter(Context context) {
            super(context, R.layout.row, R.id.header);
            for(int i=0; i < 50; i++){
                add(Integer.toString(i));
            }
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            if(convertView == null){
                convertView = LayoutInflater.from(getContext()).inflate(R.layout.row, parent, false);
                ViewHolder holder = new ViewHolder();
                holder.header = (TextView) convertView.findViewById(R.id.header);
                convertView.setTag(holder);             
            }
            ViewHolder holder = (ViewHolder) convertView.getTag();
            holder.header.setText(getItem(position));
            return convertView;
        }
    }

    private static class ViewHolder {
        TextView header;
        int previousTop = 0;
    }
}