(c#)一个关于Panel的AutoScroll=true的疑问,问题解决，散分 (100分)

//-------------------------------------------------------------------------------
// 名称：ScrollPanel.cs
// 功能：一个可以自动滚动的Panel(其实Panel也可以AutoScroll,但，当panel中的控件重新得到焦点
//                               后，会自动回滚到起始位置)
// 建立人：chinaplate          建立时间：2003-04-15-14
// TODO: 
//     1.右下角的button未处理
//	   2.panel中元件暂时只能放在(0,0)处
//--------------------------------------------------------------------------------

using System;
using System.Windows.Forms;
namespace Study
{
	public class ScrollPanel:Panel
	{
		#region Data Member
		protected const int SCROLL_WIDTH=16;
		protected const string OWNER_TAG="_ownered";
		protected HScrollBar m_hscrollBar;
		protected VScrollBar m_vscrollBar;
		protected Button m_scrollBtn;
		protected bool m_autoscroll;
		#endregion
		
		#region Constructor
		public ScrollPanel()
		{
			initializtion();
			//
			// TODO: 在此处添加构造函数逻辑
			//
			scrollPanelConstrutor();
		}
		#endregion
		#region Private Function Member
		private void scrollPanelConstrutor()
		{
			m_autoscroll=false;
		}
		private void setScrollLoction()
		{
			m_hscrollBar.Visible=false;
			m_vscrollBar.Visible=false;
			m_scrollBtn.Visible=false;
			m_hscrollBar.Height=SCROLL_WIDTH;
			m_hscrollBar.Width=this.Width-SCROLL_WIDTH;
			m_hscrollBar.Left=0;
			m_hscrollBar.Top=this.Height-SCROLL_WIDTH;

			m_vscrollBar.Width=SCROLL_WIDTH;
			m_vscrollBar.Height=this.Height-SCROLL_WIDTH;
			m_vscrollBar.Top=0;
			m_vscrollBar.Left=this.Width-SCROLL_WIDTH;
			m_scrollBtn.Height=SCROLL_WIDTH;
			m_scrollBtn.Width=SCROLL_WIDTH;
			m_scrollBtn.Left=this.Width-SCROLL_WIDTH;
			m_scrollBtn.Top=this.Height-SCROLL_WIDTH;
			m_hscrollBar.Visible=true;
			m_vscrollBar.Visible=true;
			m_scrollBtn.Visible=true;
		}
		private void initializtion()
		{
			m_hscrollBar=new HScrollBar();
			m_vscrollBar=new VScrollBar();
			m_scrollBtn=new Button();
			m_hscrollBar.Tag=OWNER_TAG;
			m_vscrollBar.Tag=OWNER_TAG;
			m_scrollBtn.Tag=OWNER_TAG;
			
			m_vscrollBar.Scroll+=new ScrollEventHandler(vscrollBar_Scroll);
			m_hscrollBar.Scroll+=new ScrollEventHandler(hscrollBar_Scroll);
			m_scrollBtn.Click+=new EventHandler(scrollBtn_Click);

			setScrollLoction();
			this.Controls.AddRange(new Control[]{
													m_hscrollBar,
													m_vscrollBar,
													m_scrollBtn
												});
			
		}
		private bool isOwnerdControl(Control con)
		{
			bool ret=false;
			if(con.Tag!=null &&
con.Tag.ToString()==OWNER_TAG) ret=true;
			return ret;
		}
		private void autosizePanel()
		{
			m_hscrollBar.Enabled=false;
			m_vscrollBar.Enabled=false;
			//m_scrollBtn.Enabled=false;
			if(m_autoscroll)
			{
				int maxH=0;
				int maxV=0;
				int curH=0;
				int curV=0;
				foreach(Control con in this.Controls)
				{
					if(!isOwnerdControl(con))
					{
						//TODO:panel中元件暂时只能放在(0,0)处
						curH=0+con.Width;
						curV=0+con.Height;
						if(maxH<curH) maxH=curH;
						if(maxV<curV) maxV=curV;
					}
				}
				//curH,V有了新的含义了
				curH=(maxH+SCROLL_WIDTH)-this.Width;
				curV=(maxV+SCROLL_WIDTH)-this.Height;
				if(curH>0)
				{
					m_hscrollBar.Minimum=0;
					m_hscrollBar.Maximum=curH;
					m_hscrollBar.Enabled=true;
				}
				if(curV>0)
				{
					m_vscrollBar.Minimum=0;
					m_vscrollBar.Maximum=curV;
					m_vscrollBar.Enabled=true;
				}
			}

		}
		#endregion
		#region Protected Function Member
		protected override void OnSizeChanged(EventArgs e)
		{
			setScrollLoction();
			autosizePanel();
			base.OnSizeChanged(e);
		}
		
		protected override void OnControlAdded(ControlEventArgs e)
		{
			e.Control.SizeChanged+=new EventHandler(control_SizeChanged);
			base.OnControlAdded(e);
		}
		#endregion
		#region Public Property
		public new bool AutoScroll
		{
			set
			{
				m_autoscroll=value;
				autosizePanel();
			}
			get
			{
				return m_autoscroll;
			}
		}
		#endregion
		#region Event Declare
		public event ScrollEventHandler HScrollScroll;
		public event ScrollEventHandler VScrollScroll;
		//btn事件的保留
		protected virtual void OnHScrollScroll(ScrollEventArgs e)
		{
			foreach(Control con in this.Controls)
			{
				if(!isOwnerdControl(con))
				{
					//TODO:panel中元件暂时只能放在(0,0)处
					con.Left=0-e.NewValue;
				}
			}
			
			if(HScrollScroll!=null)
			{
				
				HScrollScroll(this,e);
			}
		}
		protected virtual void OnVScrollScroll(ScrollEventArgs e)
		{
			foreach(Control con in this.Controls)
			{
				if(!isOwnerdControl(con))
				{
					//TODO:panel中元件暂时只能放在(0,0)处
					con.Top=0- e.NewValue;
				}
			}
			
			if(VScrollScroll!=null)
			{
				VScrollScroll(this,e);
			}
		}

		#endregion
		#region Event Member
		
		private void hscrollBar_Scroll(object sender,ScrollEventArgs e)
		{
			OnHScrollScroll(e);
		}
		private void vscrollBar_Scroll(object sender,ScrollEventArgs e)
		{
			OnVScrollScroll(e);
		}
		private void scrollBtn_Click(object sender,EventArgs e)
		{
			//保留
		}

		private void control_SizeChanged(object sender,EventArgs e)
		{
			autosizePanel();
		}
		#endregion
		
	}
}