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Extract Icon

I need to extract an icon from a file (usually a data file for an application) and put it into an ImageList. I did this in VB6 using APIs but am having difficulty in vb.net.

Any code to help me understand appreciated.
0
broadbent
Asked:
broadbent
  • 2
1 Solution
 
Bob LearnedCommented:
Public Class Graphics_Library

  ' Determine how many icons a file has.
  Private Declare Function ExtractIconEx _
    Lib "shell32.dll" Alias "ExtractIconExA" _
      (ByVal lpszFile As String, ByVal nIconIndex As Integer, _
      ByRef phiconLarge As Integer, ByRef phiconSmall As Integer, _
      ByVal nIcons As Integer) As Integer

  ' Load the icons from a file.
  Private Declare Function ExtractIcon _
    Lib "shell32.dll" Alias "ExtractIconA" _
     (ByVal hInst As IntPtr, ByVal lpszExeFileName As String, _
      ByVal nIconIndex As Integer) As Integer

  ' Release the icon handle's resources.
  Private Declare Function DestroyIcon _
    Lib "user32" _
      (ByVal hIcon As Integer) As Integer

  ' Handles to each icon.
  Private Shared m_hIcons() As Integer


  Protected Overrides Sub Finalize()

    MyBase.Finalize()

    ' Close all the icon to release their resources.

    Dim countIcons As Integer = m_hIcons.Length

    If countIcons > 0 Then

      For iconIndex As Integer = 0 To countIcons - 1

        Me.DestroyIcon(m_hIcons(iconIndex))

      Next iconIndex

    End If

  End Sub 'Finalize'


  Public Shared Function ExtractIcons(ByVal filePath As String) As Icon()

    Try

      ' Extract all of the regular-sized icons from the file pointed to by
      ' <filePath> to an array of Icon objects.  
      '
      ' NOTE:  Dynamically allocated arrays are used to receive the icon handles.  

      ' Dynamic array to receive handles to the icons.

      ' Return value for API calls.
      Dim retVal As Integer

      ' Application instance handle.
      Dim hInst As IntPtr = Me.hInstance

      ' Determine how many regular icons exist in the file and resize
      ' the array accordingly.
      Dim numIcons As Integer = ExtractIconEx(filePath, -1, 0&, 0&, 0&)

      If numIcons = 0 Then
        Throw New Exception("No icons found in " & filePath)
      End If

      ' Since arrays are 0-based, then set the upper bounds to n-1.
      numIcons -= 1

      ' Resize the arrays to hold all the handles.
      ReDim m_hIcons(numIcons)

      Dim listIcons(numIcons) As Icon

      ' Loop through each icon, creating a bitmap, .
      For currentIcon As Integer = 0 To numIcons

        ' Get all of the icon handles.
        m_hIcons(currentIcon) = ExtractIcon(hInst, filePath, currentIcon)

        Dim handleIcon As New IntPtr(m_hIcons(currentIcon))

        If Not handleIcon.Equals(IntPtr.Zero) Then

          ' Get a bitmap image from the icon handle.
          listIcons(currentIcon) = Icon.FromHandle(handleIcon)

        End If

      Next currentIcon

      ' Return the array of Icon objects.
      Return listIcons

    Catch ex As Exception

      MessageBox.Show(ex.ToString)

    End Try

  End Function 'ExtractIcons'

  Private Shared ReadOnly Property hInstance() As IntPtr
    Get
      Return Marshal.GetHINSTANCE([Assembly].GetExecutingAssembly.GetModules()(0))
    End Get
  End Property 'hInstance'

End Class


Usage:
Dim allIcons() As Icon = Graphics_Library(<path to file>)


Bob
0
 
Bob LearnedCommented:
I had to pull this from a larger application, so let me know if you have any questions or problems.

Bob
0
 
broadbentAuthor Commented:
I haven't tried it yet, but it looks very similar to my VB6 code.
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