C#获取文件图标

原作者不详

一点不足,文件夹图标是从shell32.dll中得到的.一般情况下是没有问题的.但是当文件夹的图片时自定义的时候就无法得到了.继续研究中


using System;
using System.IO;
using System.Drawing;
using Microsoft.Win32;


using System.Runtime.InteropServices;


namespace Allinhands.Common
{
    ///
    /// 提供从操作系统读取图标的方法
    ///
    public class GetSystemIcon
    {
        ///
        /// 依据文件名读取图标，若指定文件不存在，则返回空值。
        ///
        ///
        ///
        public Icon GetIconByFileName(string fileName)
        {
            if(fileName == null || fileName.Equals(string.Empty)) return null;
            if(!File.Exists(fileName)) return null;

            SHFILEINFO shinfo = new SHFILEINFO();
            //Use this to get the small Icon
            Win32.SHGetFileInfo(fileName, 0, ref shinfo,(uint)Marshal.SizeOf(shinfo),Win32.SHGFI_ICON|Win32.SHGFI_SMALLICON);
            //The icon is returned in the hIcon member of the shinfo struct
            System.Drawing.Icon myIcon = System.Drawing.Icon.FromHandle(shinfo.hIcon);
            return myIcon;
        }

        ///
        /// 给出文件扩展名（.*），返回相应图标
        /// 若不以"."开头则返回文件夹的图标。
        ///
        ///
        ///
        ///
        public Icon GetIconByFileType(string fileType,bool isLarge)
        {
            if(fileType == null || fileType.Equals(string.Empty)) return null;

            RegistryKey regVersion = null;
            string regFileType = null;
            string regIconString = null;
            string systemDirectory = Environment.SystemDirectory + "\\";

            if(fileType[0] == '.')
            {
                //读系统注册表中文件类型信息
                regVersion = Registry.ClassesRoot.OpenSubKey(fileType, true);
                if(regVersion != null)
                {
                    regFileType = regVersion.Getvalue("") as string;
                    regVersion.Close();
                    regVersion = Registry.ClassesRoot.OpenSubKey(regFileType + @"\DefaultIcon" , true);
                    if(regVersion != null)
                    {
                        regIconString = regVersion.Getvalue("") as string ;
                        regVersion.Close();
                    }
                }
                if(regIconString == null)
                {
                    //没有读取到文件类型注册信息，指定为未知文件类型的图标
                    regIconString = systemDirectory +"shell32.dll,0";
                }
            }
            else
            {
                //直接指定为文件夹图标
                regIconString = systemDirectory +"shell32.dll,3";
            }
            string[] fileIcon = regIconString.Split(new char[]{','});
            if(fileIcon.Length != 2)
            {
                //系统注册表中注册的标图不能直接提取，则返回可执行文件的通用图标
                fileIcon = new string[]{systemDirectory +"shell32.dll","2"};
            }
            Icon resultIcon = null;
            try
            {
                //调用API方法读取图标
                int[] phiconLarge = new int[1];
                int[] phiconSmall = new int[1];
                uint count = Win32.ExtractIconEx(fileIcon[0],Int32.Parse(fileIcon[1]),phiconLarge,phiconSmall,1);
                IntPtr IconHnd = new IntPtr(isLarge?phiconLarge[0]:phiconSmall[0]);
                resultIcon = Icon.FromHandle(IconHnd);
            }
            catch{}
            return resultIcon;
        }
    }



    [StructLayout(LayoutKind.Sequential)]
    public 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;
    };

    ///
    /// 定义调用的API方法
    ///
    class Win32
    {
        public const uint SHGFI_ICON = 0x100;
        public const uint SHGFI_LARGEICON = 0x0; // 'Large icon
        public const uint SHGFI_SMALLICON = 0x1; // 'Small icon

        [DllImport("shell32.dll")]
        public static extern IntPtr SHGetFileInfo(string pszPath, uint dwFileAttributes, ref SHFILEINFO psfi, uint cbSizeFileInfo, uint uFlags);
        [DllImport("shell32.dll")]
        public static extern uint ExtractIconEx(string lpszFile, int nIconIndex, int[] phiconLarge, int[] phiconSmall, uint nIcons);

    }
}