Get the Icon for a Given Extension

Get the icon for a given extension

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;
}

How to get the icon for a file extension or filetype without creating a temp file?

Looks like you already discovered the way to do it, unless you want to dive into native libraries etc.

FileSystemView uses Win32ShellFolder internally so they are basically the same.

I also dug up the Source for org.eclipse.swt.program.Program and with it org.eclipse.swt.internal.win32.OS. The OS class then uses a native call for the Icon. At this point unless you really really cannot create a Temp File i would not go down that path.

For JDIC i only found http://kickjava.com/src/org/jdesktop/jdic/tray/internal/impl/WinTrayIconService.java.htm with a little bit of digging(may not be related but does icony things :D). Also calls native.

Fastest way to get the extension name and icon by an file extension?

Firstly: Are you getting millions of icons? If you're ony getting one or a few hundred, then does it really matter which is fastest? How slow is too slow? THe best way is to try the code and time it to see if it's worth worrying about.

Secondly: Is the speed difference really a problem? Using SHGetFileInfo is more likely to work on every operating system version and will be compatible with however Microsoft do things in future - Reading the registry may not work in some cases. How will you test it?

Finally, having weighed up the above questions, the best approach is to write the 10 lines of code that it will take to try all three approaches and simply see which one is fastest.

How can I get large icons for a file extension using Windows shell?

The sizes for shell icons are given in the documentation for SHGetImageList:

• 16x16 = small
• 32x32 = large
• 48x48 = extralarge
• 256x256 = jumbo

So it is expected that when you ask for the "large" icons, you get 32x32. If you want the extralarge icon, you need to get them from the SHIL_EXTRALARGE image list.

How do I get common file type icons in C#?

Take a look at: http://mvolo.com/display-pretty-file-icons-in-your-aspnet-applications-with-iconhandler/

It's not the cleanest solution but it works. Otherwise, try to get your hands on a library of Icons that's based on mime type or file extension.

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