Get the icon for a given extension

Question

I know i can extract a file's icon using

using (System.Drawing.Icon sysicon = System.Drawing.Icon.ExtractAssociatedIcon(filePath)) {     icon = System.Windows.Interop.Imaging.CreateBitmapSourceFromHIcon(         sysicon.Handle,         System.Windows.Int32Rect.Empty,         System.Windows.Media.Imaging.BitmapSizeOptions.FromEmptyOptions()); } 

But how can I, with no file, get the icon for a given extension?

Answer 1

Use the GetFileIcon method from this CodeProject article from Paul Ingles and pass .ext as the name parameter.

The GetFileIcon method is a wrapper around the native SHGetFileInfo and copied here for illustration:

public static System.Drawing.Icon GetFileIcon(string name, IconSize size,                                                bool linkOverlay) {     Shell32.SHFILEINFO shfi = new Shell32.SHFILEINFO();     uint flags = Shell32.SHGFI_ICON | Shell32.SHGFI_USEFILEATTRIBUTES;      if (true == linkOverlay) flags += Shell32.SHGFI_LINKOVERLAY;       /* Check the size specified for return. */     if (IconSize.Small == size)     {         flags += Shell32.SHGFI_SMALLICON ; // include the small icon flag     }      else      {         flags += Shell32.SHGFI_LARGEICON ;  // include the large icon flag     }      Shell32.SHGetFileInfo( name,          Shell32.FILE_ATTRIBUTE_NORMAL,          ref shfi,          (uint) System.Runtime.InteropServices.Marshal.SizeOf(shfi),          flags );       // Copy (clone) the returned icon to a new object, thus allowing us      // to call DestroyIcon immediately     System.Drawing.Icon icon = (System.Drawing.Icon)                          System.Drawing.Icon.FromHandle(shfi.hIcon).Clone();     User32.DestroyIcon( shfi.hIcon ); // Cleanup     return icon; } 

Answer 2

Below code is also based on Paul Ingles solution, but:

• Usable with WPF (ImageSource instead of Icon)
• Has simple caching
• Removed all stuff related to directories (I have only files in my case)
• Refactored using R# tips and wrapped with a single-class simple API

I've tested it on Windows 7 and Windows XP SP3, it works as expected with any string as a fileName.

using System; using System.Collections.Generic; using System.Drawing; using System.IO; using System.Runtime.InteropServices; using System.Windows; using System.Windows.Interop; using System.Windows.Media; using System.Windows.Media.Imaging;  /// <summary> /// Internals are mostly from here: http://www.codeproject.com/Articles/2532/Obtaining-and-managing-file-and-folder-icons-using /// Caches all results. /// </summary> public static class IconManager {     private static readonly Dictionary<string, ImageSource> _smallIconCache = new Dictionary<string, ImageSource>();     private static readonly Dictionary<string, ImageSource> _largeIconCache = new Dictionary<string, ImageSource>();     /// <summary>     /// Get an icon for a given filename     /// </summary>     /// <param name="fileName">any filename</param>     /// <param name="large">16x16 or 32x32 icon</param>     /// <returns>null if path is null, otherwise - an icon</returns>     public static ImageSource FindIconForFilename(string fileName, bool large)     {         var extension = Path.GetExtension(fileName);         if (extension == null)             return null;         var cache = large ? _largeIconCache : _smallIconCache;         ImageSource icon;         if (cache.TryGetValue(extension, out icon))             return icon;         icon = IconReader.GetFileIcon(fileName, large ? IconReader.IconSize.Large : IconReader.IconSize.Small, false).ToImageSource();         cache.Add(extension, icon);         return icon;     }     /// <summary>     /// http://stackoverflow.com/a/6580799/1943849     /// </summary>     static ImageSource ToImageSource(this Icon icon)     {         var imageSource = Imaging.CreateBitmapSourceFromHIcon(             icon.Handle,             Int32Rect.Empty,             BitmapSizeOptions.FromEmptyOptions());         return imageSource;     }     /// <summary>     /// Provides static methods to read system icons for both folders and files.     /// </summary>     /// <example>     /// <code>IconReader.GetFileIcon("c:\\general.xls");</code>     /// </example>     static class IconReader     {         /// <summary>         /// Options to specify the size of icons to return.         /// </summary>         public enum IconSize         {             /// <summary>             /// Specify large icon - 32 pixels by 32 pixels.             /// </summary>             Large = 0,             /// <summary>             /// Specify small icon - 16 pixels by 16 pixels.             /// </summary>             Small = 1         }         /// <summary>         /// Returns an icon for a given file - indicated by the name parameter.         /// </summary>         /// <param name="name">Pathname for file.</param>         /// <param name="size">Large or small</param>         /// <param name="linkOverlay">Whether to include the link icon</param>         /// <returns>System.Drawing.Icon</returns>         public static Icon GetFileIcon(string name, IconSize size, bool linkOverlay)         {             var shfi = new Shell32.Shfileinfo();             var flags = Shell32.ShgfiIcon | Shell32.ShgfiUsefileattributes;             if (linkOverlay) flags += Shell32.ShgfiLinkoverlay;             /* Check the size specified for return. */             if (IconSize.Small == size)                 flags += Shell32.ShgfiSmallicon;             else                 flags += Shell32.ShgfiLargeicon;             Shell32.SHGetFileInfo(name,                 Shell32.FileAttributeNormal,                 ref shfi,                 (uint)Marshal.SizeOf(shfi),                 flags);             // Copy (clone) the returned icon to a new object, thus allowing us to clean-up properly             var icon = (Icon)Icon.FromHandle(shfi.hIcon).Clone();             User32.DestroyIcon(shfi.hIcon);     // Cleanup             return icon;         }     }     /// <summary>     /// Wraps necessary Shell32.dll structures and functions required to retrieve Icon Handles using SHGetFileInfo. Code     /// courtesy of MSDN Cold Rooster Consulting case study.     /// </summary>     static class Shell32     {         private const int MaxPath = 256;         [StructLayout(LayoutKind.Sequential)]         public struct Shfileinfo         {             private const int Namesize = 80;             public readonly IntPtr hIcon;             private readonly int iIcon;             private readonly uint dwAttributes;             [MarshalAs(UnmanagedType.ByValTStr, SizeConst = MaxPath)]             private readonly string szDisplayName;             [MarshalAs(UnmanagedType.ByValTStr, SizeConst = Namesize)]             private readonly string szTypeName;         };         public const uint ShgfiIcon = 0x000000100;     // get icon         public const uint ShgfiLinkoverlay = 0x000008000;     // put a link overlay on icon         public const uint ShgfiLargeicon = 0x000000000;     // get large icon         public const uint ShgfiSmallicon = 0x000000001;     // get small icon         public const uint ShgfiUsefileattributes = 0x000000010;     // use passed dwFileAttribute         public const uint FileAttributeNormal = 0x00000080;         [DllImport("Shell32.dll")]         public static extern IntPtr SHGetFileInfo(             string pszPath,             uint dwFileAttributes,             ref Shfileinfo psfi,             uint cbFileInfo,             uint uFlags             );     }     /// <summary>     /// Wraps necessary functions imported from User32.dll. Code courtesy of MSDN Cold Rooster Consulting example.     /// </summary>     static class User32     {         /// <summary>         /// Provides access to function required to delete handle. This method is used internally         /// and is not required to be called separately.         /// </summary>         /// <param name="hIcon">Pointer to icon handle.</param>         /// <returns>N/A</returns>         [DllImport("User32.dll")]         public static extern int DestroyIcon(IntPtr hIcon);     } }