窗体阴影，求助

[weixin_38054840]

using System;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Drawing.Drawing2D;


namespace Goodnews
{
public partial class SkinForm : Form
{
private login Main;
//带参构造
public SkinForm(login main)
{
//将控制层传值过来
this.Main = main;
InitializeComponent();
//置顶窗体
Main.TopMost = TopMost = Main.TopMost;
Main.BringToFront();
//是否在任务栏显示
ShowInTaskbar = false;
//无边框模式
FormBorderStyle = FormBorderStyle.None;
//设置绘图层显示位置
this.Location = new Point(Main.Location.X - 5, Main.Location.Y - 5);
//设置ICO
Icon = Main.Icon;
ShowIcon = Main.ShowIcon;
//设置大小
Width = Main.Width + 10;
Height = Main.Height + 10;
//设置标题名
Text = Main.Text;
//绘图层窗体移动
Main.LocationChanged += new EventHandler(Main_LocationChanged);
Main.SizeChanged += new EventHandler(Main_SizeChanged);
Main.VisibleChanged += new EventHandler(Main_VisibleChanged);
//还原任务栏右键菜单
//CommonClass.SetTaskMenu(Main);
//加载背景
SetBits();
//窗口鼠标穿透效果
CanPenetrate();
}


#region 初始化
private void Init()
{
//置顶窗体
TopMost = Main.TopMost;
Main.BringToFront();
//是否在任务栏显示
ShowInTaskbar = false;
//无边框模式
FormBorderStyle = FormBorderStyle.None;
//设置绘图层显示位置
this.Location = new Point(Main.Location.X - 5, Main.Location.Y - 5);
//设置ICO
Icon = Main.Icon;
ShowIcon = Main.ShowIcon;
//设置大小
Width = Main.Width + 10;
Height = Main.Height + 10;
//设置标题名
Text = Main.Text;
//绘图层窗体移动
Main.LocationChanged += new EventHandler(Main_LocationChanged);
Main.SizeChanged += new EventHandler(Main_SizeChanged);
Main.VisibleChanged += new EventHandler(Main_VisibleChanged);
//还原任务栏右键菜单
//CommonClass.SetTaskMenu(Main);
//加载背景
SetBits();
//窗口鼠标穿透效果
CanPenetrate();
}
#endregion

#region 还原任务栏右键菜单
protected override CreateParams CreateParams
{
get
{
CreateParams cParms = base.CreateParams;
cParms.ExStyle |= 0x00080000; // WS_EX_LAYERED
return cParms;
}
}
public class CommonClass
{
[DllImport("user32.dll", EntryPoint = "GetWindowLong", CharSet = CharSet.Auto)]
static extern int GetWindowLong(HandleRef hWnd, int nIndex);
[DllImport("user32.dll", EntryPoint = "SetWindowLong", CharSet = CharSet.Auto)]
static extern IntPtr SetWindowLong(HandleRef hWnd, int nIndex, int dwNewLong);
public const int WS_SYSMENU = 0x00080000;
public const int WS_MINIMIZEBOX = 0x20000;
public static void SetTaskMenu(Form form)
{
int windowLong = (GetWindowLong(new HandleRef(form, form.Handle), -16));
SetWindowLong(new HandleRef(form, form.Handle), -16, windowLong | WS_SYSMENU | WS_MINIMIZEBOX);
}
}
#endregion

#region 减少闪烁
private void SetStyles()
{
SetStyle(
ControlStyles.UserPaint |
ControlStyles.AllPaintingInWmPaint |
ControlStyles.OptimizedDoubleBuffer |
ControlStyles.ResizeRedraw |
ControlStyles.DoubleBuffer, true);
//强制分配样式重新应用到控件上
UpdateStyles();
base.AutoScaleMode = AutoScaleMode.None;
}
#endregion

#region 控件层相关事件
//移动主窗体时
void Main_LocationChanged(object sender, EventArgs e)
{
Location = new Point(Main.Left - 5, Main.Top - 5);
}

//主窗体大小改变时
void Main_SizeChanged(object sender, EventArgs e)
{
//设置大小
Width = Main.Width + 10;
Height = Main.Height + 10;
SetBits();
}

//主窗体显示或隐藏时
void Main_VisibleChanged(object sender, EventArgs e)
{
this.Visible = Main.Visible;
}
#endregion

#region 使窗口有鼠标穿透功能
/// <summary>
/// 使窗口有鼠标穿透功能
/// </summary>
private void CanPenetrate()
{
int intExTemp = Win32.GetWindowLong(this.Handle, Win32.GWL_EXSTYLE);
int oldGWLEx = Win32.SetWindowLong(this.Handle, Win32.GWL_EXSTYLE, Win32.WS_EX_TRANSPARENT | Win32.WS_EX_LAYERED);
}
#endregion

#region 不规则无毛边方法
public void SetBits()
{
//绘制绘图层背景
Bitmap bitmap = new Bitmap(Main.Width + 10, Main.Height + 10);
Rectangle _BacklightLTRB = new Rectangle(20, 20, 20, 20);//窗体光泽重绘边界
Graphics g = Graphics.FromImage(bitmap);
g.SmoothingMode = SmoothingMode.HighQuality; //高质量
g.PixelOffsetMode = PixelOffsetMode.HighQuality; //高像素偏移质量
ImageDrawRect.DrawRect(g, Properties.Resources.main_light_bkg_top123, ClientRectangle, Rectangle.FromLTRB(_BacklightLTRB.X, _BacklightLTRB.Y, _BacklightLTRB.Width, _BacklightLTRB.Height), 1, 1);

if (!Bitmap.IsCanonicalPixelFormat(bitmap.PixelFormat) || !Bitmap.IsAlphaPixelFormat(bitmap.PixelFormat))
throw new ApplicationException("图片必须是32位带Alhpa通道的图片。");
IntPtr oldBits = IntPtr.Zero;
IntPtr screenDC = Win32.GetDC(IntPtr.Zero);
IntPtr hBitmap = IntPtr.Zero;
IntPtr memDc = Win32.CreateCompatibleDC(screenDC);

try
{
Win32.Point topLoc = new Win32.Point(Left, Top);
Win32.Size bitMapSize = new Win32.Size(Width, Height);
Win32.BLENDFUNCTION blendFunc = new Win32.BLENDFUNCTION();
Win32.Point srcLoc = new Win32.Point(0, 0);

hBitmap = bitmap.GetHbitmap(Color.FromArgb(0));
oldBits = Win32.SelectObject(memDc, hBitmap);

blendFunc.BlendOp = Win32.AC_SRC_OVER;
blendFunc.SourceConstantAlpha = Byte.Parse("255");
blendFunc.AlphaFormat = Win32.AC_SRC_ALPHA;
blendFunc.BlendFlags = 0;

Win32.UpdateLayeredWindow(Handle, screenDC, ref topLoc, ref bitMapSize, memDc, ref srcLoc, 0, ref blendFunc, Win32.ULW_ALPHA);
}
finally
{
if (hBitmap != IntPtr.Zero)
{
Win32.SelectObject(memDc, oldBits);
Win32.DeleteObject(hBitmap);
}
Win32.ReleaseDC(IntPtr.Zero, screenDC);
Win32.DeleteDC(memDc);
}
}
#endregion
}
}
上面的阴影方法，在 login : Form里面   private SkinForm skin;调用  但是这个只能用在 login窗体里，因为上面的方法里定义了 
private login Main;
所以我想在其他窗体里应用窗体阴影，有没有什么可以不用每个窗体建立一个单独的上面阴影类？