Using system icons for TreeView in C#

Question

I'm making a file transfer app, and I need to use system icons so the icons will match different versions of Windows. They are remote files are distant so I can't just use SHFILEINFO.

uhm, is this C# or C? You may either want to change your title or the C# tag. And by 'distant' you mean on another machine? — Steffen Winkler, Jul 04 '17 at 14:14
Sorry, typo :( And yes, it's on an other computer (It's my own protocol, not standard TCP or SMB) — ERROR404_NAME_NOT_FOUND, Jul 04 '17 at 19:44
okay, just one more bit of information needed: Is your application based on WPF or WindowsForms? And the icons are to be displayed inside the treeview of your application? — Steffen Winkler, Jul 04 '17 at 19:52
It's WindowsForms, and yes, I need to display the Icon in the tree view of the app. thanks — ERROR404_NAME_NOT_FOUND, Jul 04 '17 at 22:57
In that case shfileinfo should work. You just don't pass the entire filename but only the extension. Check https://stackoverflow.com/q/2701263/937093 — Steffen Winkler, Jul 05 '17 at 05:32
Thanks, It' works :) But thee is still one little problem :/ — ERROR404_NAME_NOT_FOUND, Jul 05 '17 at 12:51

score 1 · Accepted Answer · answered Jul 05 '17 at 12:55

So, I got it working by using this very good example from CodeProject:

public 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>
    /// Options to specify whether folders should be in the open or closed state.
    /// </summary>
    public enum FolderType
    {
        /// <summary>
        /// Specify open folder.
        /// </summary>
        Open = 0,
        /// <summary>
        /// Specify closed folder.
        /// </summary>
        Closed = 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 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;
        }
        else
        {
            flags += Shell32.SHGFI_LARGEICON;
        }

        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 clean-up properly
        System.Drawing.Icon icon = (System.Drawing.Icon)System.Drawing.Icon.FromHandle(shfi.hIcon).Clone();
        User32.DestroyIcon(shfi.hIcon);     // Cleanup
        return icon;
    }

    /// <summary>
    /// Used to access system folder icons.
    /// </summary>
    /// <param name="size">Specify large or small icons.</param>
    /// <param name="folderType">Specify open or closed FolderType.</param>
    /// <returns>System.Drawing.Icon</returns>
    public static System.Drawing.Icon GetFolderIcon(IconSize size, FolderType folderType)
    {
        // Need to add size check, although errors generated at present!
        uint flags = Shell32.SHGFI_ICON | Shell32.SHGFI_USEFILEATTRIBUTES;

        if (FolderType.Open == folderType)
        {
            flags += Shell32.SHGFI_OPENICON;
        }

        if (IconSize.Small == size)
        {
            flags += Shell32.SHGFI_SMALLICON;
        }
        else
        {
            flags += Shell32.SHGFI_LARGEICON;
        }

        // Get the folder icon
        Shell32.SHFILEINFO shfi = new Shell32.SHFILEINFO();
        Shell32.SHGetFileInfo(@"Folder",
            Shell32.FILE_ATTRIBUTE_DIRECTORY,
            ref shfi,
            (uint)System.Runtime.InteropServices.Marshal.SizeOf(shfi),
            flags);

        System.Drawing.Icon.FromHandle(shfi.hIcon); // Load the icon from an HICON handle

        // Now clone the icon, so that it can be successfully stored in an ImageList
        System.Drawing.Icon icon = (System.Drawing.Icon)System.Drawing.Icon.FromHandle(shfi.hIcon).Clone();

        User32.DestroyIcon(shfi.hIcon);     // Cleanup
        return icon;
    }

    public static System.Drawing.Icon GetDriveIcon(IconSize size, FolderType folderType)
    {
        // Need to add size check, although errors generated at present!
        uint flags = Shell32.SHGFI_ICON | Shell32.SHGFI_USEFILEATTRIBUTES;

        if (FolderType.Open == folderType)
        {
            flags += Shell32.SHGFI_OPENICON;
        }

        if (IconSize.Small == size)
        {
            flags += Shell32.SHGFI_SMALLICON;
        }
        else
        {
            flags += Shell32.SHGFI_LARGEICON;
        }

        // Get the folder icon
        Shell32.SHFILEINFO shfi = new Shell32.SHFILEINFO();
        Shell32.SHGetFileInfo(null,
            Shell32.FILE_ATTRIBUTE_DIRECTORY,
            ref shfi,
            (uint)System.Runtime.InteropServices.Marshal.SizeOf(shfi),
            flags);

        System.Drawing.Icon.FromHandle(shfi.hIcon); // Load the icon from an HICON handle

        // Now clone the icon, so that it can be successfully stored in an ImageList
        System.Drawing.Icon icon = (System.Drawing.Icon)System.Drawing.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>
/// 

// This code has been left largely untouched from that in the CRC example. The main changes have been moving
// the icon reading code over to the IconReader type.
public class Shell32
{

    public const int MAX_PATH = 256;
    [StructLayout(LayoutKind.Sequential)]
    public struct SHITEMID
    {
        public ushort cb;
        [MarshalAs(UnmanagedType.LPArray)]
        public byte[] abID;
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct ITEMIDLIST
    {
        public SHITEMID mkid;
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct BROWSEINFO
    {
        public IntPtr hwndOwner;
        public IntPtr pidlRoot;
        public IntPtr pszDisplayName;
        [MarshalAs(UnmanagedType.LPTStr)]
        public string lpszTitle;
        public uint ulFlags;
        public IntPtr lpfn;
        public int lParam;
        public IntPtr iImage;
    }

    // Browsing for directory.
    public const uint BIF_RETURNONLYFSDIRS = 0x0001;
    public const uint BIF_DONTGOBELOWDOMAIN = 0x0002;
    public const uint BIF_STATUSTEXT = 0x0004;
    public const uint BIF_RETURNFSANCESTORS = 0x0008;
    public const uint BIF_EDITBOX = 0x0010;
    public const uint BIF_VALIDATE = 0x0020;
    public const uint BIF_NEWDIALOGSTYLE = 0x0040;
    public const uint BIF_USENEWUI = (BIF_NEWDIALOGSTYLE | BIF_EDITBOX);
    public const uint BIF_BROWSEINCLUDEURLS = 0x0080;
    public const uint BIF_BROWSEFORCOMPUTER = 0x1000;
    public const uint BIF_BROWSEFORPRINTER = 0x2000;
    public const uint BIF_BROWSEINCLUDEFILES = 0x4000;
    public const uint BIF_SHAREABLE = 0x8000;

    [StructLayout(LayoutKind.Sequential)]
    public struct SHFILEINFO
    {
        public const int NAMESIZE = 80;
        public IntPtr hIcon;
        public int iIcon;
        public uint dwAttributes;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = MAX_PATH)]
        public string szDisplayName;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = NAMESIZE)]
        public string szTypeName;
    };

    public const uint SHGFI_ICON = 0x000000100;     // get icon
    public const uint SHGFI_DISPLAYNAME = 0x000000200;     // get display name
    public const uint SHGFI_TYPENAME = 0x000000400;     // get type name
    public const uint SHGFI_ATTRIBUTES = 0x000000800;     // get attributes
    public const uint SHGFI_ICONLOCATION = 0x000001000;     // get icon location
    public const uint SHGFI_EXETYPE = 0x000002000;     // return exe type
    public const uint SHGFI_SYSICONINDEX = 0x000004000;     // get system icon index
    public const uint SHGFI_LINKOVERLAY = 0x000008000;     // put a link overlay on icon
    public const uint SHGFI_SELECTED = 0x000010000;     // show icon in selected state
    public const uint SHGFI_ATTR_SPECIFIED = 0x000020000;     // get only specified attributes
    public const uint SHGFI_LARGEICON = 0x000000000;     // get large icon
    public const uint SHGFI_SMALLICON = 0x000000001;     // get small icon
    public const uint SHGFI_OPENICON = 0x000000002;     // get open icon
    public const uint SHGFI_SHELLICONSIZE = 0x000000004;     // get shell size icon
    public const uint SHGFI_PIDL = 0x000000008;     // pszPath is a pidl
    public const uint SHGFI_USEFILEATTRIBUTES = 0x000000010;     // use passed dwFileAttribute
    public const uint SHGFI_ADDOVERLAYS = 0x000000020;     // apply the appropriate overlays
    public const uint SHGFI_OVERLAYINDEX = 0x000000040;     // Get the index of the overlay

    public const uint FILE_ATTRIBUTE_DIRECTORY = 0x00000010;
    public const uint FILE_ATTRIBUTE_NORMAL = 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>
public 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);
}

But, There is still one problem: The icons look HORRIBLE ! Here is a screenshot:

Do someone know how I can solve this ?

It's the same for me :( Blech! Those icons are just gross! Sorry.. — Momoro, Apr 28 '20 at 05:18
@Momoro honestly, it's been 3 years and I still haven't figured it out — ERROR404_NAME_NOT_FOUND, Apr 28 '20 at 18:33
Maybe using your own custom icons could be an alternative? https://learn.microsoft.com/en-us/dotnet/framework/winforms/controls/creating-an-explorer-style-interface-with-the-listview-and-treeview **Is a pretty good one - Needs some extra work, though :D** — Momoro, Apr 28 '20 at 20:17
From your screenshot from 3 years ago, it looks like the images are a bit distorted. I used the code from this answer, and the background for the drive image is black, and not transparent. I'd suggest saving the drive image and making the background transparent, rather than attempting to make it transparent through code. You could save the drive image as a BMP, using your `GetDriveIcon()` and the `bmp.Save()` method. Google "saving a BMP in C#", and it should come up. — Momoro, Apr 28 '20 at 20:25
Also, could you link the CodeProject page that you found this code? Thanks ;) — Momoro, Apr 29 '20 at 23:41
Sorry, it's been so long I don't even have the computer I used to work on this anymore :) — ERROR404_NAME_NOT_FOUND, Apr 30 '20 at 12:13
Oh, that's fine :) I think I found it anyway. (https://www.codeproject.com/Articles/2532/Obtaining-and-managing-file-and-folder-icons-using) — Momoro, Apr 30 '20 at 20:55

Using system icons for TreeView in C#

1 Answers1