由文件名获取文件图标（原码）

核心代码：

using System;
 using System.Runtime.InteropServices;
 using System.Drawing;
 namespace WindowsAppTmp
 { 
 
  public class ExtractIcon
  { 
 
   [DllImport("Shell32.dll")]
   private static extern int  SHGetFileInfo
    (
    string pszPath,
    uint dwFileAttributes,
    out SHFILEINFO psfi,
    uint cbfileInfo,
    SHGFI uFlags
    );  [StructLayout(LayoutKind.Sequential)]
    private struct SHFILEINFO
   { 
 
    public SHFILEINFO(bool b)
    { 
 
     hIcon=IntPtr.Zero;iIcon=0;dwAttributes=0;szDisplayName="";szTypeName="";
    }
    public IntPtr hIcon;
    public int iIcon;
    public uint dwAttributes;
    [MarshalAs(UnmanagedType.LPStr, SizeConst=260)]
    public string szDisplayName;
    [MarshalAs(UnmanagedType.LPStr, SizeConst=80)]
    public string szTypeName;
   };  private ExtractIcon()
   { 
 
   }  private enum SHGFI
   { 
 
    SmallIcon   = 0x00000001,
    LargeIcon   = 0x00000000,
    Icon    = 0x00000100,
    DisplayName   = 0x00000200,
    Typename   = 0x00000400,
    SysIconIndex  = 0x00004000,
    UseFileAttributes = 0x00000010
   }   public static Icon GetIcon(string strPath, bool bSmall)
   { 
 
    SHFILEINFO info = new SHFILEINFO(true);
    int cbFileInfo = Marshal.SizeOf(info);
    SHGFI flags;
    if (bSmall)
     flags = SHGFI.Icon|SHGFI.SmallIcon|SHGFI.UseFileAttributes;
    else
     flags = SHGFI.Icon|SHGFI.LargeIcon|SHGFI.UseFileAttributes;   SHGetFileInfo(strPath, 256, out info,(uint)cbFileInfo, flags);
    return Icon.FromHandle(info.hIcon);
   }
  }
 }