Retrieving shell icons

Retrieving shell icons

 

• Download source files - 4 Kb
• Download demo project - 27 Kb
• Download per-compiled demo - 16 Kb

Introduction

Some time ago I had to use a folder icon in one of my projects. Because I like consistent UI's, I decided to dispose the icon that is used by the Windows Explorer. As some of you may know, this icon is contained in the shell32.dll at position 3 for a closed folder, and 4 for an open folder. You can extract such icons by using ExtractIconEx. So this has been easy to implement. So far, so good.

Unfortunately, a few days later a co-worker annotated, that my code did not respect his customized shell icons. After some research, I discovered how you can change the icons used by Windows to present folders as well as some other items.

Basics

You just have to add a value to the registry at HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Shell Icons. Its name is the index of the shell icon you want to change, and the value data contains the filename of the icon and its index, separated by ','. E.g. following registry value changes the icon of open folders to that icon in C:\OpenFolder.ico (for .ico files you have to set the index to 0):

 

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Shell Icons]
"4"="C:\OpenFolder.ico,0"

The Code

As a solution, I have implemented the following method:

 

Shrink ▲   

HICON ExtractShellIcon (int nIndex,
                              bool bLargeIcons /*= false*/)
{
    HICON hIcon = NULL;

    // Shell icons can be customized by the registry:
    // HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\
    // Explorer\Shell Icons
    // "<ShellIconIndex>" = "<Filename>,<IconIndex>"
    // E.g.
    // "3" = "c:\MyFolderIcon.ico,1"
    HKEY hkeyShellIcons;
    if (RegOpenKeyEx (
        HKEY_LOCAL_MACHINE,
        _T("SOFTWARE\\Microsoft\\Windows\\
        CurrentVersion\\Explorer\\Shell Icons"),
        0,
        KEY_READ,
        &hkeyShellIcons) == ERROR_SUCCESS)
    {
        TCHAR szBuffer[ MAX_PATH * sizeof TCHAR];
        DWORD dwSize = MAX_PATH * sizeof TCHAR;

        TCHAR szIndex[6] = {0};
        _stprintf (szIndex, _T("%d"), nIndex);
        if (RegQueryValueEx (hkeyShellIcons, szIndex,
                            NULL, NULL, (LPBYTE)szBuffer,
                             &dwSize) == ERROR_SUCCESS)
        {
#ifdef _AFXDLL
            CString strFileName, strIndex;
            VERIFY (AfxExtractSubString (strFileName,
                                    szBuffer, 0, _T(',')));
            VERIFY (AfxExtractSubString (strIndex,
                                    szBuffer, 1, _T(',')));
            ExtractIconEx (
                strFileName,
                atoi(strIndex),
                bLargeIcons ? &hIcon : NULL,
                bLargeIcons ? NULL : &hIcon,
                1);
#else
            std::vector<std::tstring> ls;
            tokenize (std::back_inserter(ls),
                              szBuffer, _T(","));
            ExtractIconEx (
                ls[0].c_str(),
                atoi(ls[1].c_str()),
                bLargeIcons ? &hIcon : NULL,
                bLargeIcons ? NULL : &hIcon,
                1);
#endif
        }
        
        RegCloseKey( hkeyShellIcons );
    }

    // Not customized? Then get the original icon from
    // shell23.dll
    if (!hIcon)
        ExtractIconEx (
            _T("SHELL32.DLL"),
            nIndex, bLargeIcons ? &hIcon : NULL,
            bLargeIcons ? NULL : &hIcon,
            1);

    return hIcon;
}

Annotation

You may have noticed the tokenize function called in the non-MFC version. It's just a simple tokenizer included in the source file.

Usage

To use my method, you can just call ExtractShellIcon. The first parameter specifies, which icon you want to retrieve. I've compiled a list of icons contained in shell32.dll below. The second parameter just says whether you want a small or a large icon.

Table of available shell icons

0	SI_UNKNOWN	Unknown File Type
1	SI_DEF_DOCUMENT	Default document
2	SI_DEF_APPLICATION	Default application
3	SI_FOLDER_CLOSED	Closed folder
4	SI_FOLDER_OPEN	Open folder
5	SI_FLOPPY_514	5 1/4 floppy
6	SI_FLOPPY_35	3 1/2 floppy
7	SI_REMOVABLE	Removable drive
8	SI_HDD	Hard disk drive
9	SI_NETWORKDRIVE	Network drive
10	SI_NETWORKDRIVE_DISCONNECTED	network drive offline
11	SI_CDROM	CD drive
12	SI_RAMDISK	RAM disk
13	SI_NETWORK	Entire network
14		?
15	SI_MYCOMPUTER	My Computer
16	SI_PRINTMANAGER	Printer Manager
17	SI_NETWORK_NEIGHBORHOOD	Network Neighborhood
18	SI_NETWORK_WORKGROUP	Network Workgroup
19	SI_STARTMENU_PROGRAMS	Start Menu Programs
20	SI_STARTMENU_DOCUMENTS	Start Menu Documents
21	SI_STARTMENU_SETTINGS	Start Menu Settings
22	SI_STARTMENU_FIND	Start Menu Find
23	SI_STARTMENU_HELP	Start Menu Help
24	SI_STARTMENU_RUN	Start Menu Run
25	SI_STARTMENU_SUSPEND	Start Menu Suspend
26	SI_STARTMENU_DOCKING	Start Menu Docking
27	SI_STARTMENU_SHUTDOWN	Start Menu Shutdown
28	SI_SHARE	Sharing overlay (hand)
29	SI_SHORTCUT	Shortcut overlay (small arrow)
30	SI_PRINTER_DEFAULT	Default printer overlay (small tick)
31	SI_RECYCLEBIN_EMPTY	Recycle bin empty
32	SI_RECYCLEBIN_FULL	Recycle bin full
33	SI_DUN	Dial-up Network Folder
34	SI_DESKTOP	Desktop
35	SI_CONTROLPANEL	Control Panel
36	SI_PROGRAMGROUPS	Program Group
37	SI_PRINTER	Printer
38	SI_FONT	Font Folder
39	SI_TASKBAR	Taskbar
40	SI_AUDIO_CD	Audio CD
41		?
42		?
43	SI_FAVORITES	IE favorites
44	SI_LOGOFF	Start Menu Logoff
45		?
46		?
47	SI_LOCK	Lock
48	SI_HIBERNATE	Hibernate

You might have noticed that they're a several gaps in this table. Unfortunately, I do not know currently what these icons are used for.

The demo application

The demo provided with this article simply takes the constants depicted in the table above and inserts the associated icons into two listview ctrl's, one with large icons, the other with small ones.