Failed Launch Returns LastErrorCode 0

capaho · **Joined:** Fri Jul 21, 2006 12:28 am **Posts:** 509

I have an application that launches a PDF help file from the menu, but in Windows 7, FolderItem.Launch returns a FolderItem.LastErrorCode of 0 if no PDF reader is installed on the system. Any recommendations as to how to check for a default application for PDF files prior to launch if a failed launch under this condition doesn't return a valid error code?

markwalsh · **Joined:** Wed May 20, 2009 4:43 pm **Posts:** 958

capaho wrote:

I have an application that launches a PDF help file from the menu, but in Windows 7, FolderItem.Launch returns a FolderItem.LastErrorCode of 0 if no PDF reader is installed on the system. Any recommendations as to how to check for a default application for PDF files prior to launch if a failed launch under this condition doesn't return a valid error code?

This is what I have used, haven't checked it on Windows 7

Dim acrobatInstalled as Boolean
Dim r as RegistryItem
acrobatInstalled = true
#IF TargetWin32 THEN
  Try
    r = New RegistryItem("HKEY_CLASSES_ROOT\Software\Adobe\Acrobat\Exe", False)
  Catch
    'MsgBox "Failed to find Acrobat Reader."
    acrobatInstalled = False
  End Try
#ENDIF

capaho · **Joined:** Fri Jul 21, 2006 12:28 am **Posts:** 509

Quote:

This is what I have used, haven't checked it on Windows 7

Dim acrobatInstalled as Boolean
Dim r as RegistryItem
acrobatInstalled = true
#IF TargetWin32 THEN
  Try
    r = New RegistryItem("HKEY_CLASSES_ROOT\Software\Adobe\Acrobat\Exe", False)
  Catch
    'MsgBox "Failed to find Acrobat Reader."
    acrobatInstalled = False
  End Try
#ENDIF

Thanks for the code snippet. I'll give it a try.

capaho · **Joined:** Fri Jul 21, 2006 12:28 am **Posts:** 509

The code snippet solved the problem although I had to add an exception handler to trap a RegistryAccessErrorException that occurs if the application is not run as administrator.

charonn0 · **Posted:** Wed Feb 29, 2012 12:51 pm

A little late, but here's another way:

Function FindDefaultApp(Extends documentFile As FolderItem) As FolderItem
  //Given a documentFile FolderItem, will return a FolderItem corresponding to the application currently
  //associated with the file (e.g. a .doc file might return C:\Program Files\Microsoft Office\winword.exe)
  //If no application is associated with the documentFile, the documentFile doesn't exist, or is inaccessble
  //then this function returns Nil.
  //If the documentFile is itself an application (.exe, .scr, etc.) then this function returns a FolderItem
  //corresponding to the documentFile itself (e.g. "C:\foo\bar.exe" is associated with itself.)
  
  #If TargetWin32 Then
    Declare Function FindExecutableW Lib "Shell32" (file As WString, directory As WString, result As Ptr) As Integer
    
    Dim mb As New MemoryBlock(260)
    If FindExecutableW(documentFile.AbsolutePath, Nil, mb) > 32 Then
      Return GetFolderItem(mb.WString(0))
    End If
  #endif
End Function

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Failed Launch Returns LastErrorCode 0