Getting Associated Icons Using VB .NET

Summary

This step-by-step article describes how to use the SHGetFileInfo function to get the icons that are associated with files.

Create a Windows Forms Application

1. Start Microsoft Visual Studio .NET.
2. On the File menu, point to New, and then click Project.
3. In the New Project dialog box, click Visual Basic Projects under Project Types, and then click Windows Application under Templates.
4. In the Name box, type GetIconSample.

Use the SHGetFileInfo Function

1. Add the following code at the beginning of the Form1.vb file:

Imports System.Runtime.InteropServices

2. Add the following code in the Form1 class after the INHERITS statement:

Private Structure SHFILEINFO
        Public hIcon As IntPtr            ' : icon
        Public iIcon As Integer           ' : icondex
        Public dwAttributes As Integer    ' : SFGAO_ flags
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=260)> _
        Public szDisplayName As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=80)> _
        Public szTypeName As String
End Structure

Private Declare Auto Function SHGetFileInfo Lib "shell32.dll" _
        (ByVal pszPath As String, _
         ByVal dwFileAttributes As Integer, _
         ByRef psfi As SHFILEINFO, _
         ByVal cbFileInfo As Integer, _
         ByVal uFlags As Integer) As IntPtr

Private Const SHGFI_ICON      = &H100
Private Const SHGFI_SMALLICON = &H1
Private Const SHGFI_LARGEICON = &H0    ' Large icon
Private nIndex                = 0

3. Add a listView control, a button control, and an imageList control to the form. The default names are ListView1, Button1, and ImageList1, respectively.
4. In the Properties window of Button1, set the button text to Select a File, and then add the following code in the Button1_click event:

Dim hImgSmall As IntPtr  'The handle to the system image list.
Dim hImgLarge As IntPtr  'The handle to the system image list.
Dim fName As String      'The file name to get the icon from.
Dim shinfo As SHFILEINFO
shinfo = New SHFILEINFO()
Dim openFileDialog1 As OpenFileDialog
openFileDialog1 = New OpenFileDialog()

openFileDialog1.InitialDirectory = "c:\temp\"
openFileDialog1.Filter           = "All files (*.*)|*.*"
openFileDialog1.FilterIndex      = 2
openFileDialog1.RestoreDirectory = True

listView1.SmallImageList = imageList1
listView1.LargeImageList = ImageList1

shinfo.szDisplayName = New String(Chr(0), 260)
shinfo.szTypeName    = New String(Chr(0), 80)

If (openFileDialog1.ShowDialog() = DialogResult.OK) Then
     fName = openFileDialog1.FileName

     'Use this to get the small icon.
     hImgSmall = SHGetFileInfo(fName, 0, shinfo, _
                 Marshal.SizeOf(shinfo), _
                 SHGFI_ICON Or SHGFI_SMALLICON)

     'Use this to get the large icon.
     'hImgLarge = SHGetFileInfo(fName, 0,
     'ref shinfo, (uint)Marshal.SizeOf(shinfo),
     'SHGFI_ICON | SHGFI_LARGEICON);

     'The icon is returned in the hIcon member of the
     'shinfo struct.
     Dim myIcon As System.Drawing.Icon
     myIcon = System.Drawing.Icon.FromHandle(shinfo.hIcon)

     imageList1.Images.Add(myIcon)       'Add icon to
                                         'imageList.

     listView1.Items.Add(fName, nIndex)  'Add file name and
                                         'icon to listview.
     nIndex = nIndex + 1
End If

Run The Project

1. Compile the project: On the Build menu, click Build Solution.
2. Press F5 to run the project.
3. Click Select a File, and then select a file in the Open dialog box. The name of the file and the icon that are associated with the file appear in the ListView control.