package com.wasu.cs.widget.wheelview;

import android.database.DataSetObserver;
import android.view.View;
import android.view.ViewGroup;

/**
 * Wheel items adapter interface
 */
public interface WheelViewAdapter {
    /**
     * Gets items count
     * 
     * @return the count of wheel items
     */
    public int getCount();

    /**
     * Get a View that displays the data at the specified position in the data set
     * 
     * @param index the item index
     * @param convertView the old view to reuse if possible
     * @param parent the parent that this view will eventually be attached to
     * @return the wheel item View
     */
    public View getView(int index, View convertView, ViewGroup parent);

    /**
     * Get a View that displays an empty wheel item placed before the first or after the last wheel
     * item.
     * 
     * @param convertView the old view to reuse if possible
     * @param parent the parent that this view will eventually be attached to
     * @return the empty item View
     */
    public View getEmptyItem(View convertView, ViewGroup parent);

    /**
     * Register an observer that is called when changes happen to the data used by this adapter.
     * 
     * @param observer the observer to be registered
     */
    public void registerDataSetObserver(DataSetObserver observer);

    /**
     * Unregister an observer that has previously been registered
     * 
     * @param observer the observer to be unregistered
     */
    void unregisterDataSetObserver(DataSetObserver observer);
}
