C# 获取系统Icon、获取文件相关的Icon

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace FileExplorer
{
    /// <summary>
    /// 系统Icon
    /// 1、Get()  获取指定索引对应的系统icon 
    /// 2、Save() 保存所有系统图像
    /// 3、Show() 显示所有系统Icon图像
    /// </summary>
    public partial class SystemIcon : Form
    {
        public SystemIcon()
        {
            InitializeComponent();

            Show(this);
            Save();
        }
        
        /// <summary>
        /// 在form上显示所有系统icon图像
        /// </summary>
        public static void Show(Form form)
        {
            LoadSystemIcon();

            FlowLayoutPanel flowLayout = new FlowLayoutPanel();
            flowLayout.Dock = System.Windows.Forms.DockStyle.Fill;
            flowLayout.AutoScroll = true;

            for (int i = 0; i < SystemIconList.Count; i++)
            {
                PictureBox pic = new PictureBox();
                pic.Size = new System.Drawing.Size(32, 32);
                flowLayout.Controls.Add(pic);

                Bitmap p = SystemIconList[i].ToBitmap();
                pic.Image = p;
            }
            form.Controls.Add(flowLayout);
        }

        /// <summary>
        /// 保存所有系统图像
        /// </summary>
        public static void Save()
        {
            LoadSystemIcon();

            for (int i = 0; i < SystemIconList.Count; i++)
            {
                Bitmap p = SystemIconList[i].ToBitmap();

                // 保存图像
                string path = AppDomain.CurrentDomain.BaseDirectory + "系统图标\\";
                string filepath = path + (i + ".png");
                if (!Directory.Exists(path)) Directory.CreateDirectory(path);
                if (!File.Exists(filepath)) p.Save(filepath);
            }
        }

        /// <summary>
        /// 获取指定索引对应的系统icon
        /// </summary>
        public static Icon Get(int index)
        {
            LoadSystemIcon();
            return index < SystemIconList.Count ? SystemIconList[index] : null;
        }


        private static List<Icon> SystemIconList = new List<Icon>(); // 记录系统图标

        //[DllImport("user32.dll", CharSet = CharSet.Auto)]
        //private static extern bool MessageBeep(uint type);

        [DllImport("Shell32.dll")]
        public extern static int ExtractIconEx(string libName, int iconIndex, IntPtr[] largeIcon, IntPtr[] smallIcon, int nIcons);

        private static IntPtr[] largeIcon;
        private static IntPtr[] smallIcon;

        /// <summary>
        /// 获取所有系统icon图像
        /// </summary>
        private static void LoadSystemIcon()
        {
            if (SystemIconList.Count > 0) return;

            largeIcon = new IntPtr[1000];
            smallIcon = new IntPtr[1000];

            ExtractIconEx("shell32.dll", 0, largeIcon, smallIcon, 1000);

            SystemIconList.Clear();
            for (int i = 0; i < largeIcon.Length; i++)
            {
                try
                {
                    Icon ic = Icon.FromHandle(largeIcon[i]);
                    SystemIconList.Add(ic);
                }
                catch (Exception ex) 
                {
                    break;
                }
            }
        }


        //private void LoadSystemIcon()
        //{
        //    largeIcon = new IntPtr[1000];
        //    smallIcon = new IntPtr[1000];

        //    ExtractIconEx("shell32.dll", 0, largeIcon, smallIcon, 1000);


        //    FlowLayoutPanel flowLayout = new FlowLayoutPanel();
        //    flowLayout.Dock = System.Windows.Forms.DockStyle.Fill;
        //    flowLayout.AutoScroll = true;

        //    for (int i = 0; i < largeIcon.Length; i++)
        //    {
        //        try
        //        {
        //            PictureBox pic = new PictureBox();
        //            pic.Size = new System.Drawing.Size(32, 32);
        //            flowLayout.Controls.Add(pic);

        //            Icon ic = Icon.FromHandle(largeIcon[i]);
        //            SystemIcon.Add(ic);

        //            Bitmap p = ic.ToBitmap();
        //            pic.Image = p;

        //            // 保存图像
        //            string path = AppDomain.CurrentDomain.BaseDirectory + "系统图标\\";
        //            string filepath = path + (i + ".png");
        //            if (!Directory.Exists(path)) Directory.CreateDirectory(path);
        //            if (!File.Exists(filepath)) p.Save(filepath);
        //        }
        //        catch (Exception ex)
        //        {
        //            break;
        //        }
        //    }
        //    this.Controls.Add(flowLayout);
        //}
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using System.IO;
using System.Drawing;
using Microsoft.Win32;

namespace FileExplorer
{
    /// <summary>
    /// 获取指定文件的Icon图像getIcon()、getIcon2()
    /// </summary>
    class FileIcon
    {
        private const uint SHGFI_ICON = 0x100;
        private const uint SHGFI_LARGEICON = 0x0;  //大图标
        private const uint SHGFI_SMALLICON = 0x1;  //小图标

        [StructLayout(LayoutKind.Sequential)]
        public struct SHFILEINFO
        {
            public IntPtr hIcon;        //文件的图标句柄  

            public IntPtr iIcon;        //图标的系统索引号  

            public uint dwAttributes;   //文件的属性值  

            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
            public string szDisplayName;//文件的显示名  


            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 80)]
            public string szTypeName;   //文件的类型名  
        };

        [DllImport("shell32.dll")]
        private static extern IntPtr SHGetFileInfo(string pszPath, uint dwFileAttributes, ref SHFILEINFO psfi, uint cbSizeFileInfo, uint uFlags);

        /// <summary>
        /// 获取文件FilePath对应的Icon
        /// </summary>
        public static Icon getIcon(string FilePath)
        {
            SHFILEINFO shinfo = new SHFILEINFO();
            //FileInfo info = new FileInfo(FileName);

            //大图标
            SHGetFileInfo(FilePath, 0, ref shinfo, (uint)Marshal.SizeOf(shinfo), SHGFI_ICON | SHGFI_LARGEICON);
            Icon largeIcon = Icon.FromHandle(shinfo.hIcon);

            //Icon.ExtractAssociatedIcon(FileName);
            return largeIcon;
        }

        /// <summary>
        /// 获取文件FilePath对应的Icon
        /// </summary>
        public static Icon getIcon2(string FilePath)
        {
            return Icon.ExtractAssociatedIcon(FilePath);
        }
    }
}