获取ListView垂直滚动条上一页/下一页事件

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace scrollBarStudy
{
    public partial class PageView : ListView
    {
        public event EventHandler ShowMessage;

        public PageView()
        {
            InitializeComponent();
        }
        protected override void WndProc(ref Message m)
        {
            int WM_VSCROLL = 0x115;
            int WM_HSCROLL = 0x114;


            if (m.Msg == WM_VSCROLL)
            {
                switch ((uint)m.WParam)
                {
                    // Page up
                    case 0:
                        MessageBox.Show("up!");
                        base.WndProc(ref m);
                        break;
                    case 1:
                        MessageBox.Show("Down!");
                        base.WndProc(ref m);
                        break;
                    default:
                        base.WndProc(ref m);
                        break;
                }
            }


            base.WndProc(ref m); 

        }
       
    }
}