C#獲取windows系統的圖標

這個獲取關聯圖標，能夠獲取磁盤分區的圖標，能夠獲取某個特定類型的文件的圖標，也能夠獲取某個指定文件的圖標
/// <summary>
/// 保存文件信息的結構體
/// </summary>
/// 
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
struct SHFILEINFO
{
    public IntPtr hIcon;
    public int iIcon;
    public uint dwAttributes;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
    public string szDisplayName;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 80)]
    public string szTypeName;
}

class NativeMethods
{

    [DllImport("Shell32.dll", EntryPoint = "SHGetFileInfo", SetLastError = true, CharSet = CharSet.Auto)]
    public static extern IntPtr SHGetFileInfo(string pszPath, uint dwFileAttributes, ref SHFILEINFO psfi, uint cbFileInfo, uint uFlags);

    [DllImport("User32.dll", EntryPoint = "DestroyIcon")]
    public static extern int DestroyIcon(IntPtr hIcon);

    #region API 參數的常量定義

    public const uint SHGFI_ICON = 0x100;
    public const uint SHGFI_LARGEICON = 0x0; //大圖標 32×32
    public const uint SHGFI_SMALLICON = 0x1; //小圖標 16×16
    public const uint SHGFI_USEFILEATTRIBUTES = 0x10;

    #endregion

}
/// <summary>
/// 獲取文件類型的關聯圖標
/// </summary>
/// <param name="fileName">文件類型的擴展名或文件的絕對路徑</param>
/// <param name="isLargeIcon">是否返回大圖標</param>
/// <returns>獲取到的圖標</returns>
static Icon GetIcon(string fileName, bool isLargeIcon)
{
    SHFILEINFO shfi = new SHFILEINFO();
    IntPtr hI;

    if (isLargeIcon)
        hI = NativeMethods.SHGetFileInfo(fileName, 0, ref shfi, (uint)Marshal.SizeOf(shfi), NativeMethods.SHGFI_ICON | NativeMethods.SHGFI_USEFILEATTRIBUTES | NativeMethods.SHGFI_LARGEICON);
    else
        hI = NativeMethods.SHGetFileInfo(fileName, 0, ref shfi, (uint)Marshal.SizeOf(shfi), NativeMethods.SHGFI_ICON | NativeMethods.SHGFI_USEFILEATTRIBUTES | NativeMethods.SHGFI_SMALLICON);

    Icon icon = Icon.FromHandle(shfi.hIcon).Clone() as Icon;

    NativeMethods.DestroyIcon(shfi.hIcon); //釋放資源
    return icon;
}

private void btnGetIcon_Click(object sender, EventArgs e)
{
    using (Graphics g = this.pbSmallIcon.CreateGraphics())
    {
        g.Clear(this.pbSmallIcon.BackColor); //清除picturebox的背景色，爲了畫透明圖標

        g.DrawIcon(GetIcon(this.tbFileExt.Text, false), 1, 1); //繪製小圖標
    }

    using (Graphics g = this.pbLargeIcon.CreateGraphics())
    {
        g.Clear(this.pbLargeIcon.BackColor); //清除picturebox的背景色，爲了畫透明圖標

        g.DrawIcon(GetIcon(this.tbFileExt.Text, true), 1, 1); //繪製小圖標
    }
}