Question

How can i implement custom section or header of ListView like Instagram app in android.

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

When scroll up the bar that have userpic, name and time still be there and when other header bar go near it then animate like push it up.

Thank you.

Answer 1

I was able to solve this issue by using scroll listener on the listview. (tested on 2.1)

Lets say for each list row I have a layout like the one below. There is a content part and a header part. It doesn’t matter what view type you use for header or content.

<?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>

The test layout for the activity is as in the following:

<?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>

Finally the code for the activity is given below. Here I had to have an adapter which uses ViewHolder to store the header view and also a variable to keep track of the change in the scroll for each successive scroll events (previousTop). This is because of the fact that offsetTopAndBottom() changes offset of the view related to the previous location of it.

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;
    }
}