VB Forum / Win API / September 2008

Strange enough (?), my code works on WinXP like a charm, and it does
also work on Win2K for registered file types.

My first opinion was also a memory allocation problem or a bad calling
convention (ByVal instead of ByRef or vice versa) but that doesn't
explain why it works for registered file types. In that case I would
expect it to fail every time.

Nevertheless, here's snippet of my implementation:

<code>
'SHGetFileInfo Flags
Private Const SHGFI_USEFILEATTRIBUTES   As Long = &H10
Private Const SHGFI_TYPENAME            As Long = &H400

'FileAttribute flags
Private Const FILE_ATTRIBUTE_DIRECTORY              As Long = &H10
Private Const FILE_ATTRIBUTE_NORMAL                 As Long = &H80

Private Type SHFILEINFO _SHFILEINFO {
    hIcon                           As Long
    iIcon                           As Long
    dwAttributes                    As Long
    szDisplayName(519)              As Byte
    szTypeName(159)                 As Byte
End Type

Private Declare Function SHGetFileInfo Lib "shell32.dll" _
        Alias "SHGetFileInfoW" ( _
    ByVal pszPath As Long, _
    ByVal dwFileAttributes As Long, _
    psfi As SHFILEINFO, _
    ByVal cbSizeFileInfo As Long, _
    ByVal uFlags As Long) As Long

Private Sub GetFileInfo()
    'mvarExtension is initialized in the class

    On Error GoTo ErrHandler

    Static shInfo As SHFILEINFO, shInfoStructSize As Long

    Dim lRetval As Long

    If shInfoStructSize = 0 Then
        shInfoStructSize = Len(shInfo)

        'working variables...
        Dim sExtension As String, lFileAttributes As Long
        Dim lFlags As Long, sTypeName As String

        If mvarExtension = vbNullChar Then
            lFileAttributes = FILE_ATTRIBUTE_DIRECTORY
            sExtension = ""
        Else
            lFileAttributes = FILE_ATTRIBUTE_NORMAL
            sExtension = "." & mvarExtension
        End If

        'Get the system TypeName associated with that extension
        lFlags = SHGFI_TYPENAME Or SHGFI_USEFILEATTRIBUTES
        lRetval = SHGetFileInfo( _
            ByVal StrPtr(sExtension), lFileAttributes, shInfo, _
            shInfoStructSize, lFlags)

        If lRetval <> 0 Then
            sTypeName = shInfo.szTypeName   'Implicit conversion!
            mvarFileType = Left(sTypeName, _
                InStr(1, sTypeName, vbNullChar) - 1)
        Else
            GoSub LogAPIError_GetFileInfo
        End If
    'Else
    '   GetFileInfo() called before for the given extension
    End If

    Exit Sub

LogAPIError_GetFileInfo:
    'Some Warning Error Routine here

    Resume

ErrHandler:
    'Some Error Handling Routine here
End Sub

</code>

Note this snippet is only part of my implementation, so if some
declarations are missing, it's due to the selective copy-paste.

Sinna