图标拾取器（C#）版

完全是利用API实现的。
以前学习API的时候写的。现在整理一下，发给那些想知道如何实现的朋友。


using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Runtime.InteropServices;
using Microsoft.Win32;
using System.IO;

namespace GetFileIcon
{
 /// <summary>
 /// 图标拾取器
 /// 程序：房客
 /// 网址：http://www.cnblogs.com/sxlfybb/
 /// 转载请保留，谢谢
 /// </summary>
 public class Form1 : System.Windows.Forms.Form
 {
  private System.Windows.Forms.Button button1;
  private System.Windows.Forms.OpenFileDialog openFileDialog1;
  private System.Windows.Forms.PictureBox pictureBox1;
  private System.Windows.Forms.SaveFileDialog saveFileDialog1;
  private System.Windows.Forms.CheckBox checkBox1;
  private System.Windows.Forms.MainMenu mainMenu1;
  private System.Windows.Forms.MenuItem menuItem1;
  private System.Windows.Forms.MenuItem menuItem2;
  private System.Windows.Forms.MenuItem menuItem3;
  private System.Windows.Forms.MenuItem menuItem4;
  /// <summary>
  /// 必需的设计器变量。
  /// </summary>
  private System.ComponentModel.Container components = null;

  public Form1()
  {
   //
   // Windows 窗体设计器支持所必需的
   //
   InitializeComponent();

   //
   // TODO: 在 InitializeComponent 调用后添加任何构造函数代码
   //
  }

  /// <summary>
  /// 清理所有正在使用的资源。
  /// </summary>
  protected override void Dispose( bool disposing )
  {
   if( disposing )
   {
    if (components != null)
    {
     components.Dispose();
    }
   }
   base.Dispose( disposing );
  }

  #region Windows 窗体设计器生成的代码
  /// <summary>
  /// 设计器支持所需的方法 - 不要使用代码编辑器修改
  /// 此方法的内容。
  /// </summary>
  private void InitializeComponent()
  {
   this.button1 = new System.Windows.Forms.Button();
   this.openFileDialog1 = new System.Windows.Forms.OpenFileDialog();
   this.pictureBox1 = new System.Windows.Forms.PictureBox();
   this.saveFileDialog1 = new System.Windows.Forms.SaveFileDialog();
   this.checkBox1 = new System.Windows.Forms.CheckBox();
   this.mainMenu1 = new System.Windows.Forms.MainMenu();
   this.menuItem1 = new System.Windows.Forms.MenuItem();
   this.menuItem2 = new System.Windows.Forms.MenuItem();
   this.menuItem3 = new System.Windows.Forms.MenuItem();
   this.menuItem4 = new System.Windows.Forms.MenuItem();
   this.SuspendLayout();
   //
   // button1
   //
   this.button1.Location = new System.Drawing.Point(16, 32);
   this.button1.Name = "button1";
   this.button1.Size = new System.Drawing.Size(64, 23);
   this.button1.TabIndex = 0;
   this.button1.Text = "Start";
   this.button1.Click += new System.EventHandler(this.button1_Click);
   //
   // pictureBox1
   //
   this.pictureBox1.Location = new System.Drawing.Point(112, 16);
   this.pictureBox1.Name = "pictureBox1";
   this.pictureBox1.Size = new System.Drawing.Size(48, 40);
   this.pictureBox1.TabIndex = 2;
   this.pictureBox1.TabStop = false;
   //
   // checkBox1
   //
   this.checkBox1.Location = new System.Drawing.Point(24, 8);
   this.checkBox1.Name = "checkBox1";
   this.checkBox1.Size = new System.Drawing.Size(64, 24);
   this.checkBox1.TabIndex = 3;
   this.checkBox1.Text = "小图标";
   //
   // mainMenu1
   //
   this.mainMenu1.MenuItems.AddRange(new System.Windows.Forms.MenuItem[] {
                       this.menuItem1});
   //
   // menuItem1
   //
   this.menuItem1.Index = 0;
   this.menuItem1.MenuItems.AddRange(new System.Windows.Forms.MenuItem[] {
                       this.menuItem2,
                       this.menuItem3,
                       this.menuItem4});
   this.menuItem1.Text = "系统(&S)";
   //
   // menuItem2
   //
   this.menuItem2.Index = 0;
   this.menuItem2.Text = "关于(&A)";
   this.menuItem2.Click += new System.EventHandler(this.menuItem2_Click);
   //
   // menuItem3
   //
   this.menuItem3.Index = 1;
   this.menuItem3.Text = "-";
   //
   // menuItem4
   //
   this.menuItem4.Index = 2;
   this.menuItem4.Text = "退出(&X)";
   this.menuItem4.Click += new System.EventHandler(this.menuItem4_Click);
   //
   // Form1
   //
   this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
   this.ClientSize = new System.Drawing.Size(178, 63);
   this.Controls.Add(this.checkBox1);
   this.Controls.Add(this.pictureBox1);
   this.Controls.Add(this.button1);
   this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle;
   this.MaximizeBox = false;
   this.Menu = this.mainMenu1;
   this.Name = "Form1";
   this.Text = "图标拾取C#版";
   this.Load += new System.EventHandler(this.Form1_Load);
   this.ResumeLayout(false);

  }
  #endregion

  /// <summary>
  /// 应用程序的主入口点。
  /// </summary>
  [STAThread]
  static void Main()
  {
   Application.Run(new Form1());
  }

  [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;

  };

  public const uint SHGFI_ICON=0x100;
  public const uint SHGFI_SMALLICON=0x1;
  public const uint SHGFI_LARGEICON=0x0;
  public const uint SHGFI_ATTRIBUTES=0x800;
  public const uint FILE_ATTRIBUTE_NORMAL=0x80;
  public const uint SHGFI_USEFILEATTRIBUTES=0x10;

  [DllImport("shell32.dll")]

  public static extern IntPtr SHGetFileInfo(string pszPath, uint dwFileAttributes, ref SHFILEINFO psfi, uint cbSizeFileInfo, uint uFlags);

  private void button1_Click(object sender, System.EventArgs e)
  {   
   uint IconSize = SHGFI_LARGEICON;
   if(checkBox1.Checked)
    IconSize = SHGFI_SMALLICON;

   if( openFileDialog1.ShowDialog(this) == DialogResult.OK )
   {
    try
    {
     SHFILEINFO shinfo = new SHFILEINFO();
     SHGetFileInfo( openFileDialog1.FileName, 0, ref shinfo,(uint)Marshal.SizeOf(shinfo),SHGFI_ICON|IconSize);

     Icon icon = Icon.FromHandle (shinfo.hIcon);
     pictureBox1.Image = (Image)icon.ToBitmap();

     string strSavePath = string.Empty;
     
     if( MessageBox.Show(this,"是否保存图标?","询问",MessageBoxButtons.YesNo,MessageBoxIcon.Question) == DialogResult.Yes )
     {
      if (saveFileDialog1.ShowDialog(this) == DialogResult.OK)
      {
       strSavePath = saveFileDialog1.FileName;

       using (FileStream sw = new FileStream(strSavePath,FileMode.Create))
       {
        icon.Save(sw);
       }
      }
     }

    }
    catch( Exception ex )
    {
     MessageBox.Show( ex.Message );
    }
   }

  }

  private void Form1_Load(object sender, System.EventArgs e)
  {
   saveFileDialog1.Filter = "*.ico|*.ico";
   openFileDialog1.Filter = "*.*|*.*";
  }

  private void menuItem4_Click(object sender, System.EventArgs e)
  {
   Application.Exit();
  }

  private void menuItem2_Click(object sender, System.EventArgs e)
  {
   string  str = "图标拾取C#版 Ver1.0" ;
   str += System.Environment.NewLine;
   str += System.Environment.NewLine;
   str += "程序：房客 " + "\t" + "QQ：83849123";
   str += System.Environment.NewLine;
   str += "网站：http://www.cnblogs.com/sxlfybb";

   MessageBox.Show( this,str,"信息",MessageBoxButtons.OK,MessageBoxIcon.Information );
  }
 }
}