public class NativeMethods
{
    /// <summary>
    /// 帶有外邊框和標(biāo)題的windows的樣式
    /// </summary>
    public const long WS_CAPTION = 0X00C0000L;
 
    // public const long WS_BORDER = 0X0080000L;
 
    /// <summary>
    /// window 擴展樣式 分層顯示
    /// </summary>
    public const long WS_EX_LAYERED = 0x00080000L;
 
    /// <summary>
    /// 帶有alpha的樣式
    /// </summary>
    public const long LWA_ALPHA = 0x00000002L;
 
    /// <summary>
    /// 顏色設(shè)置
    /// </summary>
    public const long LWA_COLORKEY = 0x00000001L;
 
    /// <summary>
    /// window的基本樣式
    /// </summary>
    public const int GWL_STYLE = -16;
 
    /// <summary>
    /// window的擴展樣式
    /// </summary>
    public const int GWL_EXSTYLE = -20;
 
    /// <summary>
    /// 設(shè)置窗體的樣式
    /// </summary>
    /// <param name="handle">操作窗體的句柄</param>
    /// <param name="oldStyle">進行設(shè)置窗體的樣式類型.</param>
    /// <param name="newStyle">新樣式</param>
    [System.Runtime.InteropServices.DllImport("User32.dll")]
    public static extern void SetWindowLong(IntPtr handle, int oldStyle, long newStyle);
 
    /// <summary>
    /// 獲取窗體指定的樣式.
    /// </summary>
    /// <param name="handle">操作窗體的句柄</param>
    /// <param name="style">要進行返回的樣式</param>
    /// <returns>當(dāng)前window的樣式</returns>
    [System.Runtime.InteropServices.DllImport("User32.dll")]
    public static extern long GetWindowLong(IntPtr handle, int style);
 
    /// <summary>
    /// 設(shè)置窗體的工作區(qū)域.
    /// </summary>
    /// <param name="handle">操作窗體的句柄.</param>
    /// <param name="handleRegion">操作窗體區(qū)域的句柄.</param>
    /// <param name="regraw">if set to <c>true</c> [regraw].</param>
    /// <returns>返回值</returns>
    [System.Runtime.InteropServices.DllImport("User32.dll")]
    public static extern int SetWindowRgn(IntPtr handle, IntPtr handleRegion, bool regraw);
 
    /// <summary>
    /// 創(chuàng)建帶有圓角的區(qū)域.
    /// </summary>
    /// <param name="x1">左上角坐標(biāo)的X值.</param>
    /// <param name="y1">左上角坐標(biāo)的Y值.</param>
    /// <param name="x2">右下角坐標(biāo)的X值.</param>
    /// <param name="y2">右下角坐標(biāo)的Y值.</param>
    /// <param name="width">圓角橢圓的width.</param>
    /// <param name="height">圓角橢圓的height.</param>
    /// <returns>hRgn的句柄</returns>
    [System.Runtime.InteropServices.DllImport("gdi32.dll")]
    public static extern IntPtr CreateRoundRectRgn(int x1, int y1, int x2, int y2, int width, int height);
 
    /// <summary>
    /// Sets the layered window attributes.
    /// </summary>
    /// <param name="handle">要進行操作的窗口句柄</param>
    /// <param name="colorKey">RGB的值</param>
    /// <param name="alpha">Alpha的值，透明度</param>
    /// <param name="flags">附帶參數(shù)</param>
    /// <returns>true or false</returns>
    [System.Runtime.InteropServices.DllImport("User32.dll")]
    public static extern bool SetLayeredWindowAttributes(IntPtr handle, ulong colorKey, byte alpha, long flags);
}

// 獲取窗體句柄
 IntPtr hwnd = new System.Windows.Interop.WindowInteropHelper(this).Handle;
 
 // 獲得窗體的 樣式
 long oldstyle = NativeMethods.GetWindowLong(hwnd, NativeMethods.GWL_STYLE);
 
 // 更改窗體的樣式為無邊框窗體
 NativeMethods.SetWindowLong(hwnd, NativeMethods.GWL_STYLE, oldstyle & ~NativeMethods.WS_CAPTION);
 
 // SetWindowLong(hwnd, GWL_EXSTYLE, oldstyle & ~WS_EX_LAYERED);
 // 1 | 2 << 8 | 3 << 16  r=1,g=2,b=3 詳見winuse.h文件
 // 設(shè)置窗體為透明窗體
 NativeMethods.SetLayeredWindowAttributes(hwnd, 1 | 2 << 8 | 3 << 16, 0, NativeMethods.LWA_ALPHA);
 
 // 創(chuàng)建圓角窗體  12 這個值可以根據(jù)自身項目進行設(shè)置
 NativeMethods.SetWindowRgn(hwnd, NativeMethods.CreateRoundRectRgn(0, 0, Convert.ToInt32(this.ActualWidth), Convert.ToInt32(this.ActualHeight), 12, 12), true);

/// <summary>
/// Handles the SizeChanged event of the DesktopShell control.
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">The <see cref="System.Windows.SizeChangedEventArgs"/> instance containing the event data.</param>
private void DesktopShell_SizeChanged(object sender, SizeChangedEventArgs e)
{
    // 獲取窗體句柄
    IntPtr hwnd = new System.Windows.Interop.WindowInteropHelper(this).Handle;
 
    // 創(chuàng)建圓角窗體
    NativeMethods.SetWindowRgn(hwnd,NativeMethods.CreateRoundRectRgn(0, 0, Convert.ToInt32(this.ActualWidth), Convert.ToInt32(this.ActualHeight), 12, 12), true);
}