Icon.ExtractAssociatedIcon for things that are not files?

Question

Is this possible? It gives me an error, and I had previously thought it could work for folders and drives and stuff like that as well.

Icon.ExtractAssociatedIcon("C:\") did not work when I tried it, and threw an error.

How can I get the associated icon from EVERYTHING? This is vb.net

Answer 1

It is not possible to use Icon.ExtractAssociatedIcon on anything other than files. This API is a thin wrapper on top of the Win32 call ExtractAssociatedIcon. While the documentation for the managed code is a bit ambiguous, the native documentation is much clearer that the target must be a file. It goes further to say that it must be an executable file.

Unfortunately I'm not sure if there is an equivalent function for Directories or not.

Answer 2

The SHGetFileInfo() shell function can provide you with the icon you are looking for. This code worked well, it generated appropriate icons for drives, folders and files:

Imports System.Drawing
Imports System.Reflection
Imports System.Runtime.InteropServices

Public Module NativeMethods
  Public Function GetShellIcon(ByVal path As String) As Icon
    Dim info As SHFILEINFO = New SHFILEINFO()
    Dim retval as IntPtr = SHGetFileInfo(path, 0, info, Marshal.SizeOf(info), &H100)
    If retval = IntPtr.Zero Then Throw New ApplicationException("Could not retrieve icon")
    '' Invoke private Icon constructor so we do not have to copy the icon
    Dim cargt() As Type = { GetType(IntPtr) }
    Dim ci As ConstructorInfo = GetType(Icon).GetConstructor(BindingFlags.NonPublic Or BindingFlags.Instance, Nothing, cargt, Nothing)
    Dim cargs() As Object = { info.IconHandle }
    Dim icon As Icon = CType(ci.Invoke(cargs), Icon)
    Return icon
  End Function

  '' P/Invoke declaration
  Private Structure SHFILEINFO
    Public IconHandle As IntPtr
    Public IconIndex As Integer
    Public Attributes As Integer
    <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=260)> _
    Public DisplayString As String
    <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=80)> _
    Public TypeName As String
  End Structure

  Private Declare Auto Function SHGetFileInfo lib "Shell32.dll" (path As String, _
    attributes As Integer, byref info As SHFILEINFO, infoSize As Integer, flags As Integer) As IntPtr

End Module