重绘panel控件，实现panel的阴影效果

最近想在项目中添加一个要有阴影的panel控件，找了好多资料，最后通过采用图片的方式实现了panel的阴影效果，效果图如下：

重绘代码如下：

 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Drawing;
 using System.Data;
 using System.Linq;
 using System.Text;
 using System.Windows.Forms;
 using System.Drawing.Drawing2D;

 namespace ShadowPanel3
 {
     public partial class UserPanel : Panel
     {
         public UserPanel()
         {

         }
             /// <summary>
         /// 字段和属性 ， panel的颜色
         /// </summary>
         private Color _panelColor;
         public Color PanelColor
         {
             get { return _panelColor; }
             set { this._panelColor = value; }
         }

         /// <summary>
         /// 字段和属性，border的颜色
         /// </summary>
         private Color _borderColor;
         public Color BorderColor
         {
             get { return _borderColor; }
             set { this._borderColor = value; }
         }

         /// <summary>
         /// 阴影区域大小
         /// </summary>
         private int shadowSize = ;

         //将预备的小图标转化
         static Image shadowDownRight = new Bitmap(typeof(UserPanel), "Images.tshadowdownright.png");
         static Image shadowDown = new Bitmap(typeof(UserPanel), "Images.tshadowdown.png");
         static Image shadowRight = new Bitmap(typeof(UserPanel), "Images.tshadowright.png");
         static Image shadowTop = new Bitmap(typeof(UserPanel),"Images.tshadowtop.png");
         static Image shadowLeft = new Bitmap(typeof(UserPanel),"Images.tshadowleft.png");
         static Image shadowLeftDown = new Bitmap(typeof(UserPanel),"Images.tshadowleftdown.png");
         static Image shadowLeftTop = new Bitmap(typeof(UserPanel),"Images.tshadowlefttop.png");
         static Image shadowTopLeft = new Bitmap(typeof(UserPanel),"Images.tshadowtopleft.png");

         /// <summary>
         /// 重绘panel
         /// </summary>
         /// <param name="e"></param>
         protected override void OnPaint(PaintEventArgs e)
         {
             base.OnPaint(e);
             //Get the graphics object. We need something to draw with
             Graphics g = e.Graphics;

             //下边和右边画笔
             TextureBrush shadowRightBrush = new TextureBrush(shadowRight,WrapMode.Tile);
             TextureBrush shadowDownBrush = new TextureBrush(shadowDown,WrapMode.Tile);

             //上边和左边画笔
             TextureBrush shadowLeftBrush = new TextureBrush(shadowLeft, WrapMode.Tile);
             TextureBrush shadowTopBrush = new TextureBrush(shadowTop,WrapMode.Tile);

             //给画笔定位
             shadowDownBrush.TranslateTransform(, Height - shadowSize);
             shadowRightBrush.TranslateTransform(Width - shadowSize, );

             shadowTopBrush.TranslateTransform(,);
             shadowLeftBrush.TranslateTransform(,);

             //每个阴影区域非配一个矩形区域
             Rectangle shadowDownRectangle = new Rectangle(
                 shadowSize,                                                     //X
                 Height-shadowSize,                                         //Y
                 Width-shadowSize*,                                     //width(stretches)
                 shadowSize                                                    //height
                 );

             Rectangle shadowRightRectangle = new Rectangle(
               Width-shadowSize,                                           //X
               shadowSize,                                                     //Y
               shadowSize,                                                    //width
               Height-shadowSize*                                       //height(stretches)
               );

             Rectangle shadowTopRectangle = new Rectangle(
               shadowSize,                                                    //X
               ,                                                                     //Y
               Width-shadowSize*,                                       //width
               shadowSize                                                     //height(stretches)
               );

             Rectangle shadowLeftRectangle = new Rectangle(
               ,                                                                    //X
               shadowSize,                                                    //Y
               shadowSize,                                                    //width
               Height-shadowSize*                                       //height(stretches)
               );

             //在底部和右边画出阴影
             g.FillRectangle(shadowDownBrush,shadowDownRectangle);
             g.FillRectangle(shadowRightBrush,shadowRightRectangle);
             //在上部和左边画出阴影
             g.FillRectangle(shadowTopBrush,shadowTopRectangle);
             g.FillRectangle(shadowLeftBrush,shadowLeftRectangle);

             //四个角落处的阴影
             g.DrawImage(shadowDownRight, new Rectangle(Width-shadowSize, Height-shadowSize,shadowSize,shadowSize));
             g.DrawImage(shadowLeftDown, new Rectangle(, Height - shadowSize, shadowSize, shadowSize));
             g.DrawImage(shadowLeftTop, new Rectangle(, , shadowSize, shadowSize));
             g.DrawImage(shadowTopLeft, new Rectangle(Width-shadowSize, , shadowSize, shadowSize));

             Rectangle fullRectangle = new Rectangle(
                 ,
                 ,
                 Width - (shadowSize + ),
                 Height - (shadowSize + )
                 );

             if (PanelColor != null)
             {
                 SolidBrush bgBrush = new SolidBrush(_panelColor);
                 g.FillRectangle(bgBrush,fullRectangle);
             }

             //给panel添加边框颜色
             if (_borderColor != null)
             {
                 Pen borderPen = new Pen(BorderColor);
                 g.DrawRectangle(borderPen,fullRectangle);
             }

             //释放画笔资源
             shadowDownBrush.Dispose();
             shadowRightBrush.Dispose();
             shadowLeftBrush.Dispose();
             shadowTopBrush.Dispose();

             shadowDownBrush = null;
             shadowRightBrush = null;
             shadowTopBrush = null;
             shadowLeftBrush = null;
         }

             //Correct resizing
             protected override void OnResize(EventArgs e)
             {
                 base.Invalidate();
                 base.OnResize(e);
             }
     }
 }