Winform通过panel叠加实现滚动条效果

通过panel叠加实现

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

namespace LinPhoneTest
{
    public partial class Form1 : Form
    {
        int firstY = 0;
        public Form1()
        {
            InitializeComponent();

            this.panel1.MouseWheel += new MouseEventHandler(this.Panel_MouseWheel);
            firstY = panel2.Location.Y;
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            panel2.Height = 3000;
        }

        private void Panel_MouseWheel(object sender, MouseEventArgs e)
        {
            label1.Text = "TOP:"+panel2.Top.ToString()+" W:" + e.Delta;
            if (panel2.Top + panel2.Height + e.Delta < panel1.Height)
            {
                panel2.Top = panel1.Height - panel2.Height;
                return;
            }

            if (panel2.Top+e.Delta  > firstY)
            {
                panel2.Top = firstY ;
                return;
            }

            panel2.Top += e.Delta;
        }

        private void panel1_MouseEnter(object sender, EventArgs e)
        {
            this.panel1.Focus();
        }

        private void panel2_MouseEnter(object sender, EventArgs e)
        {
            this.panel1.Focus();
        }
    }
}