获取系统文件图标

在做ftp客户端的时候我们常希望我们的ListView会象资源管理器一样工作.对不同类型的文件显示不同的图标.为此我们就需要获取系统的图标:SHGetFileInfo这个API为我们提供了获取系统图标的方法.我这里把我以前写的一段程序弄上来省得要用的时候还得写了:

using  System;
using  System.Collections.Generic;
using  System.Text;
using  System.Runtime.InteropServices;
using  System.Drawing;

namespace  FTPClient
{
    public   static   class  ShellImages
   {
         #region  DLLIMPORT
         //  Retrieves information about an object in the file system,
         //  such as a file, a folder, a directory, or a drive root.
        [DllImport( " shell32 " ,
            EntryPoint  =   " SHGetFileInfo " ,
            ExactSpelling  =   false ,
            CharSet  =  CharSet.Auto,
            SetLastError  =   true )]
         private   static   extern  IntPtr SHGetFileInfo(
             string  pszPath,
            FILE_ATTRIBUTE dwFileAttributes,
             ref  SHFILEINFO sfi,
             int  cbFileInfo,
            SHGFI uFlags);
         #endregion

        #region  STRUCTS
         //  Contains information about a file object
        [StructLayout(LayoutKind.Sequential, CharSet  =  CharSet.Auto)]
         private   struct  SHFILEINFO
        {
             public  IntPtr hIcon;
             public  IntPtr iIcon;
             public   uint  dwAttributes;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst  =   260 )]
             public   string  szDisplayName;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst  =   80 )]
             public   string  szTypeName;
        };
         #endregion

         #region  Enums
         //  Flags that specify the file information to retrieve with SHGetFileInfo
        [Flags]
         public   enum  SHGFI :  uint
        {
            ADDOVERLAYS  =   0x20 ,
            ATTR_SPECIFIED  =   0x20000 ,
            ATTRIBUTES  =   0x800 ,
            DISPLAYNAME  =   0x200 ,
            EXETYPE  =   0x2000 ,
            ICON  =   0x100 ,
            ICONLOCATION  =   0x1000 ,
            LARGEICON  =   0 ,
            LINKOVERLAY  =   0x8000 ,
            OPENICON  =   2 ,
            OVERLAYINDEX  =   0x40 ,
            PIDL  =   8 ,
            SELECTED  =   0x10000 ,
            SHELLICONSIZE  =   4 ,
            SMALLICON  =   1 ,
            SYSICONINDEX  =   0x4000 ,
            TYPENAME  =   0x400 ,
            USEFILEATTRIBUTES  =   0x10
        }
         //  Flags that specify the file information to retrieve with SHGetFileInfo
        [Flags]
         public   enum  FILE_ATTRIBUTE
       {
            READONLY  =   0x00000001 ,
            HIDDEN  =   0x00000002 ,
            SYSTEM  =   0x00000004 ,
            DIRECTORY  =   0x00000010 ,
            ARCHIVE  =   0x00000020 ,
            DEVICE  =   0x00000040 ,
            NORMAL  =   0x00000080 ,
            TEMPORARY  =   0x00000100 ,
            SPARSE_FILE  =   0x00000200 ,
            REPARSE_POINT  =   0x00000400 ,
            COMPRESSED  =   0x00000800 ,
            OFFLINE  =   0x00001000 ,
            NOT_CONTENT_INDEXED  =   0x00002000 ,
            ENCRYPTED  =   0x00004000
        }
         #endregion

         #region  Variables
         // 保存小图标列表 
        private   static  System.Windows.Forms.ImageList smallImageList; 
         // 保存大图标列表 
        private   static  System.Windows.Forms.ImageList largeImageList;
         // 保存已装载的图标信息<扩展名,在imageList中的索引> 
        private   static  Dictionary < string ,  int >  loadImageDictionary;
        static  ShellImages()
       {
           smallImageList  =   new  System.Windows.Forms.ImageList();
           largeImageList  =   new  System.Windows.Forms.ImageList();
           loadImageDictionary  =   new  Dictionary < string ,  int > ();
            // 将 ImageList中的图标设置为32位色图标，这样可以得到较好的显示效果
           smallImageList.ColorDepth  =  System.Windows.Forms.ColorDepth.Depth32Bit;
           largeImageList.ColorDepth  =  System.Windows.Forms.ColorDepth.Depth32Bit;
           largeImageList.ImageSize  =   new  Size( 32 ,  32 );
           addForderIcon();
       }
         #endregion

         #region  PrivateMethods
        ///   <summary>
        ///  获取系统图标
        ///   </summary>
        ///   <param name="path"> 文件名 </param>
        ///   <param name="dwAttr"> 文件信息 </param>
        ///   <param name="dwFlag"> 获取信息控制字 </param>
        ///   <returns></returns>
         private   static  Icon GetIcon( string  path, FILE_ATTRIBUTE dwAttr, SHGFI dwFlag)
       {
           SHFILEINFO fi  =   new  SHFILEINFO();
           Icon ic  =   null ;
            int  iTotal  =  ( int )SHGetFileInfo(path, dwAttr,  ref  fi,  0 , dwFlag);
           ic  =  Icon.FromHandle(fi.hIcon);
            return  ic;
       }
        ///   <summary>
        ///  向smallInamgeList和largeImageList中
        ///  加入相应文件对应的图标
        ///   </summary>
        ///   <param name="fileName"></param>
        private   static   void  addFileIcon( string  fileName)
       {
           smallImageList.Images.Add(GetIcon(fileName,
               FILE_ATTRIBUTE.NORMAL,
               SHGFI.USEFILEATTRIBUTES  |  SHGFI.ICON  |  SHGFI.LARGEICON));
           largeImageList.Images.Add(GetIcon(fileName,
               FILE_ATTRIBUTE.NORMAL, 
               SHGFI.USEFILEATTRIBUTES  |  SHGFI.ICON  |  SHGFI.LARGEICON));
       }
        private   static   void  addForderIcon()
       {
           smallImageList.Images.Add(GetIcon( " dic " , 
               FILE_ATTRIBUTE.DIRECTORY, 
               SHGFI.USEFILEATTRIBUTES  |  SHGFI.ICON  |  SHGFI.LARGEICON));
           largeImageList.Images.Add(GetIcon( " dic " ,
               FILE_ATTRIBUTE.DIRECTORY, 
               SHGFI.USEFILEATTRIBUTES  |  SHGFI.ICON  |  SHGFI.LARGEICON));
       }
         #endregion

         #region  PublicMethods
        ///   <summary>
        ///  获取系统的小图标列表
        ///   </summary>
         public   static  System.Windows.Forms.ImageList SmallImageList
        {
             get
            {
                 return  smallImageList;
            }
            
        }
        ///   <summary>
        ///  获取系统的大图标列表
        ///   </summary>
         public   static  System.Windows.Forms.ImageList LargeImageList
        {
             get
           {
                 return  largeImageList;
            }
            
        }
        ///   <summary>
        ///  文件对应的图标在ImageList中的索引号
        ///  （在SmallImageList,LargeImageList中的索引号是相同的）
        ///   </summary>
        ///   <param name="fileName"> 文件名 </param>
         ///   <returns> 索引号 </returns>
         public   static   int  ImageIndex( string  fileName)
       {
             int  index = 0 ;
             int  extIndex  =  fileName.LastIndexOf( ' . ' );
             if  (extIndex  <   0 ) // 没有扩展名的文件当作文件夹处理
            {
                extIndex  =   2 ;
            }
             else // 文件图标索引获取
            {
                fileName  =  fileName.Substring(extIndex, fileName.Length  -  extIndex);
                 // 判断该扩展名的文件图标是否已装载到imageList中
                 if  ( ! loadImageDictionary.TryGetValue(fileName,  out  index))
                {
                    addFileIcon(fileName); // 装载图标到ImageList中
                    loadImageDictionary.Add(fileName, smallImageList.Images.Count  -   1 );
                    index  =  smallImageList.Images.Count  -   1 ;
                }
            }
             return  index;
        }
         #endregion

    }
}

 

这个类为我们提供了一个smallImageList 和largeImageList属性.还有一个ImageIndex(string)方法用来获取获取相关文件的图标对应的索引号.下面是一端使用代码:

// 为listView指定图标列表
this .listView1.SmallImageList  =  ShellImages.SmallImageList;
this .listView1.LargeImageList  =  ShellImages.LargeImageList;
// 向listview中动态添加一个节点
ListViewItem item  =   new  ListViewItem();
item.Text  =   " a.txt " ;
item.ImageIndex  =  ShellImages.ImageIndex(item.Text);
this .listView1.Items.Add(item);

欢迎大家指正.